| 1. |
- Christlieb, Norbert, et al.
(författare)
-
New Searches for R-Process Enhanced Stars
- 2001
-
Ingår i: Proceedings of "Astrophysical Ages and Times Scales", ASP Conference Series. - : Astronomical Society of the Pacific, San Francisco, U.S.A.. - 1583810838 ; , s. 298-300
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We discuss strategies for the detection of additional examples of highly r-process-enhanced, ultra-metal-poor stars, such as the two presently known examples of the class, CS~22892-052, and the newly discovered CS~31082-001. We expect that a quick, modera
|
|
| 2. |
- EDVARDSSON, Bengt, et al.
(författare)
-
ABUNDANCE ANALYSIS AND ORIGIN OF THE ZETA-SCULPTORIS OPEN CLUSTER
- 1995
-
Ingår i: ASTRONOMY AND ASTROPHYSICS. - : SPRINGER VERLAG. - 0004-6361. ; 293:1, s. 75-86
-
Tidskriftsartikel (refereegranskat)abstract
- We have determined chemical abundances and radial velocities for stars in the field of the zeta Sculptoris cluster. We find that the cluster metal deficiency previously found from UBV photometry is not supported; the cluster overall metallicity, [Fe/H] =
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Flemme, Inger, et al.
(författare)
-
Life situation of patients with an implantable cardioverter defibrillator : a descriptive longitudinal study
- 2001
-
Ingår i: Journal of Clinical Nursing. - : Wiley. - 0962-1067 .- 1365-2702. ; 10:4, s. 563-572
-
Tidskriftsartikel (refereegranskat)abstract
- • The aim of this study was to describe changes in the life situation of patients with an implantable cardioverter defibrillator over a period of 1 year. A sample of 56 consecutive patients took part in the study.• Life situation was measured through uncertainty in illness, satisfaction, and fear of the life situation. Descriptive statistics were used to present results, and analytical statistics were used to map out changes over time.• Overall uncertainty showed a decrease over time. A statistically significant difference was found within the domain uncertainty related to information (P < 0.001).• Satisfaction increased within the domains health-functioning, socio-economic, psychological–spiritual, and family.• The ability to act within the domain health-functioning showed a statistical significance (P < 0.05).• The domain life changes within fear in the life situation decreased and showed a statistical significance (P < 0.05).• The overall life situation showed increased satisfaction as well as lower uncertainty and fear in the life situation.• The research indicates that patients need more information about changes in the life situation after the implantable cardioverter defibrillator-implantation. The study encourages more humanistic, holistic research about patients’ life situations as well as more education in teaching skills for health care personnel.
|
|
| 6. |
- Garcia, Lopez Ramon J, et al.
(författare)
-
Boron in very metal-poor stars
- 1998
-
Ingår i: ASTROPHYSICAL JOURNAL. - : UNIV CHICAGO PRESS. - 0004-637X. ; 500:1, s. 241-256
-
Tidskriftsartikel (refereegranskat)abstract
- We have observed the B I lambda 2497 line to derive the boron abundances of two very metal-poor stars selected to help in tracing the origin and evolution of this element in the early Galaxy: BD +23 degrees 3130 and HD 84937. The observations were conduct
|
|
| 7. |
- Gustafsson, Bengt, et al.
(författare)
-
A grid of MARCS model atmospheres for late-type stars
- 2008
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 486:3, s. 951-970
-
Forskningsöversikt (refereegranskat)abstract
- Context. In analyses of stellar spectra and colours, and for the analysis of integrated light from galaxies, a homogeneous grid of model atmospheres of late-type stars and corresponding flux spectra is needed. Aims. We construct an extensive grid of spherically-symmetric models (supplemented with plane-parallel ones for the highest surface gravities), built on up-to-date atomic and molecular data, and make it available for public use. Methods. The most recent version of the MARCS program is used. Results. We present a grid of about 104 model atmospheres for stars with 2500K <= T-eff <= 8000 K, -1 <= log g = log (GM/R-2) <= 5 (cgs) with various masses and radii, -5 <= [Me/H] <= + 1, with [alpha/Fe] = 0.0 and 0.4 and different choices of C and N abundances. This includes "CN-cycled" models with C/N=4.07 (solar), 1.5 and 0.5, C/O ranging from 0.09 to (normally) 5.0 to also represent stars of spectral types R, S and N, and with 1.0 <= xi(t) = 5km s(-1). We also list thermodynamic quantities (T, P-g, P-e, rho, partial pressures of molecules, etc.) and provide them on the World Wide Web, as well as calculated fluxes in approximately 108 000 wavelength points. Underlying assumptions in addition to 1D stratification (spherical or plane-parallel) include hydrostatic equilibrium, mixing-length convection and local thermodynamic equilibrium. We discuss a number of general properties of the models, in particular in relation to the effects of changing abundances, of blanketing, and of sphericity. We illustrate positive and negative feedbacks between sphericity and molecular blanketing. We compare the models with those of other available grids and find excellent agreement with planeparallel models of Castelli & Kurucz (if convection is treated consistently) within the overlapping parameter range. Although there are considerable departures from the spherically-symmetric NextGen models, the agreement with more recent PHOENIX models is gratifying. Conclusions. The models of the grid show considerable regularities, but some interesting departures from general patterns occur for the coolest models due to the molecular opacities. We have tested a number of approximate "rules of thumb" concerning effects of blanketing and sphericity and often found them to be astonishingly accurate. Some interesting new phenomena have been discovered and explored, such as the intricate coupling between blanketing and sphericity, and the strong effects of carbon enhancement on metal-poor models. We give further details of line absorption data for molecules, as well as details of models and comparisons with observations in subsequent papers.
|
|
| 8. |
- Gustafsson, Bengt, et al.
(författare)
-
A new MARCS Grid
- 2002
-
Ingår i: International Astronomical Union Symposium. - 1583811605 ; , s. A2-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An extensive grid of spherically symmetric model atmospheres of stars with 1. 2500 K <= Teff <= 8000 K, 2. -1.0 <= log g (= log GM/R2) <= 5.0 (cgs units), 3. different combinations of M and R, 4. -5 <= [A/H] <= 1, and 5. a number of CNO abundance combinat
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Jonsell, Karin, 1970-
(författare)
-
Chemical Abundance Analysis of Population II Stars : The Summary Includes a Background in General Astronomy
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We are made of stardust in the sense that most atomic nuclei around us have been formed by stars. Stars synthesise new elements and expel them to the interstellar medium, from which later new generations of stars are born. We can map this chemical evolution by analysing the atmospheric contents of old Galactic halo stars. I have done two such investigations. A vigourous debate is going on whether the oxygen-to-iron ratio varies strongly with the general metal-content of halo stars. In my first study, I made an abundance analysis of 43 halo stars, and found no support for such a variation. I have also found that there probably is a cosmic spread in the abundances of oxygen, magnesium, silicon, and calcium relative to iron for halo stars. This may be an indication that the halo was built up by subsystems with differences in the star formation rate. In my second study, I performed a thorough abundance analysis of the star HE0338-3945, which is strangely overabundant in both r- and s-elements. Several other stars have been found with abundance patterns curiously similar to this star, and I define new criteria for the class r+s stars. The abundance similarities among the r+s stars suggest a common formation scenario. However, as the s-elements usually are considered to be produced in binary systems of low mass, and r-elements in supernovae of Type II, this scenario is not obvious. In the article I discuss seven hypotheses, and several of them are dismissed.
|
|
| 13. |
- Jonsell, Karin, et al.
(författare)
-
Chemical abundances in 43 metal-poor stars
- 2005
-
Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 440:1, s. 321-343
-
Tidskriftsartikel (refereegranskat)abstract
- We have derived abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni, and Ba for 43 metal-poor field stars in the solar neighbourhood, most of them subgiants or turn-off-point stars with iron abundances [Fe/H] ranging from -0.4 to -3.0. About half of this sample has not been spectroscopically analysed in detail before. Effective temperatures were estimated from uvby photometry, and surface gravities primarily from Hipparcos parallaxes. The analysis is differential relative to the Sun, and was carried out with plane-parallel MARCS models. Various sources of error are discussed and found to contribute a total error of about 0.1-0.2 dex for most elements, while relative abundances, such as [Ca/Fe], are most probably more accurate. For the oxygen abundances, determined in an NLTE analysis of the 7774 Å triplet lines, the errors may be somewhat larger. We made a detailed comparison with similar studies and traced the reasons for the, in most cases, relatively small differences. Among the results we find that [O/Fe] possibly increases beyond [Fe/H] = -1.0, though considerably less so than in results obtained by others from abundances based on OH lines. We did not trace any tendency toward strong overionization of iron, and find the excesses, relative to Fe and the Sun, of the α elements Mg, Si, and Ca to be smaller than those of O. We discuss some indications that also the abundances of different α elements relative to Fe vary and the possibility that some of the scatter around the trends in abundances relative to iron may be real. This may support the idea that the formation of Halo stars occurred in smaller systems with different star formation rates. We verify the finding by Gratton et al. (2003b, A&A, 406, 131) that stars that do not participate in the rotation of the galactic disk show a lower mean and larger spread in [ α/Fe] than stars participating in the general rotation. The latter stars also seem to show some correlation between [ α/Fe] and rotation speed. We trace some stars with peculiar abundances, among these two Ba stars, HD 17072 and HD 196944, the second already known to be rich in s elements. Finally we advocate that a spectroscopic study of a larger sample of halo stars with well-defined selection criteria is very important, in order to add to the very considerable efforts that various groups have already made.
|
|
| 14. |
- Meszaros, Sz., et al.
(författare)
-
New ATLAS9 and MARCS Model Atmosphere Grids for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
- 2012
-
Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 144:4, s. 120-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new grid of model photospheres for the SDSS-III/APOGEE survey of stellar populations of the Galaxy, calculated using the ATLAS9 and MARCS codes. New opacity distribution functions were generated to calculate ATLAS9 model photospheres. MARCS models were calculated based on opacity sampling techniques. The metallicity ([M/H]) spans from -5 to 1.5 for ATLAS and -2.5 to 0.5 for MARCS models. There are three main differences with respect to previous ATLAS9 model grids: a new corrected H2O line list, a wide range of carbon ([C/M]) and alpha element [alpha/M] variations, and solar reference abundances from Asplund et al. The added range of varying carbon and alpha-element abundances also extends the previously calculated MARCS model grids. Altogether, 1980 chemical compositions were used for the ATLAS9 grid and 175 for the MARCS grid. Over 808,000 ATLAS9 models were computed spanning temperatures from 3500 K to 30,000 K and log g from 0 to 5, where larger temperatures only have high gravities. The MARCS models span from 3500 K to 5500 K, and log g from 0 to 5. All model atmospheres are publicly available online.
|
|
| 15. |
- Plez, Bertrand, et al.
(författare)
-
A MARCS Grid of S-type Star Atmospheres
- 2003
-
Ingår i: International Astronomical Unium Symposium. - 1583811605 ; , s. A2-
-
Konferensbidrag (populärvet., debatt m.m.)
|
|
| 16. |
- Ryde, Nils, et al.
(författare)
-
A First Study of Giant Stars in the Galactic Bulge based on Crires spectra
- 2007
-
Ingår i: Stellar Populations as Building Blocks of Galaxies. ; , s. 260-261
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present our on-going work on the determination of elemental abundances of giants in the Galactic Bulge by means of infrared spectroscopy. We show a preliminarily reduced spectrum and a synthetic spectrum fit of the Bulge giant Arp 4203 recorded with the near-infrared, high-resolution Crires spectrograph mounted on the VLT during its science verification run in August 2006. Abundances derived from this spectrum are discussed.
|
|
| 17. |
- Ryde, Nils, et al.
(författare)
-
Chemical abundances of 11 bulge stars from high-resolution, near-IR spectra
- 2010
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 509:1, s. A20-
-
Tidskriftsartikel (refereegranskat)abstract
- Context. It is debated whether the Milky Way bulge has characteristics more similar to those of a classical bulge than those of a pseudobulge. Detailed abundance studies of bulge stars are important when investigating the origin, history, and classification of the bulge. These studies provide constraints on the star-formation history, initial mass function, and differences between stellar populations. Not many similar studies have been completed because of the large distance and high variable visual extinction along the line-of-sight towards the bulge. Therefore, near-IR investigations can provide superior results. Aims. To investigate the origin of the bulge and study its chemical abundances determined from near-IR spectra for bulge giants that have already been investigated with optical spectra. The optical spectra also provide the stellar parameters that are very important to the present study. In particular, the important CNO elements are determined more accurately in the near-IR. Oxygen and other alpha elements are important for investigating the star-formation history. The C and N abundances are important for determining the evolutionary stage of the giants and the origin of C in the bulge. Methods. High-resolution, near-infrared spectra in the H band were recorded using the CRIRES spectrometer mounted on the Very Large Telescope. The CNO abundances are determined from the numerous molecular lines in the wavelength range observed. Abundances of the alpha elements Si, S, and Ti are also determined from the near-IR spectra. Results. The abundance ratios [O/Fe], [Si/Fe], and [S/Fe] are enhanced to metallicities of at least [Fe/H] = -0.3, after which they decline. This suggests that the Milky Way bulge experienced a rapid and early burst of star formation similar to that of a classical bulge. However, a similarity between the bulge trend and the trend of the local thick disk seems to be present. This similarity suggests that the bulge could have had a pseudobulge origin. The C and N abundances suggest that our giants are first-ascent red-giants or clump stars, and that the measured oxygen abundances are those with which the stars were born. Our [C/Fe] trend does not show any increase with [Fe/H], which is expected if W-R stars contributed substantially to the C abundances. No "cosmic scatter" can be traced around our observed abundance trends: the measured scatter is expected, given the observational uncertainties.
|
|
| 18. |
- Thoren, Patrik, et al.
(författare)
-
Subgiants as probes of galactic chemical evolution
- 2004
-
Ingår i: Astronomy & Astrophysics. - 0004-6361. ; 425:1, s. 187-206
-
Tidskriftsartikel (refereegranskat)abstract
- Chemical abundances for 23 candidate subgiant stars have been derived with the aim at exploring their usefulness for studies of galactic chemical evolution. High-resolution spectra from ESO CAT-CES and NOT-SOFIN covered 16 different spectral regions in the visible part of the spectrum. Some 200 different atomic and molecular spectral lines have been used for abundance analysis of approximately 30 elemental species. The wings of strong, pressure-broadened metal lines were used for determination of stellar surface gravities, which have been compared with gravities derived from Hipparcos parallaxes and isochronic masses. Stellar space velocities have been derived from Hipparcos and Simbad data, and ages and masses were derived with recent isochrones. Only 12 of the stars turned out to be subgiants, i.e. on the "horizontal" part of the evolutionary track between the dwarf- and the giant stages. The abundances derived for the subgiants correspond closely to those of dwarf stars. With the possible exceptions of lithium and carbon we find that subgiant stars show no "chemical" traces of post-main-sequence evolution and that they are therefore very useful targets for studies of galactic chemical evolution.
|
|
| 19. |
- Tomkin, Jocelyn, et al.
(författare)
-
The rise and fall of the NaMgAl stars
- 1997
-
Ingår i: ASTRONOMY AND ASTROPHYSICS. - 0004-6361. ; 327:2, s. 587-597
-
Tidskriftsartikel (refereegranskat)abstract
- We have made new abundance determinations for a sample of NaMgAl stars. These stars, which are a subgroup of the nearby metal-rich field F and G disk dwarfs, were first identified by Edvardsson et al. (1993) on the basis of their apparent enrichment in Na, Mg and Al relative to other elements. The discovery of a planetary companion to the nearby solar type star 51 Peg (Mayor & Queloz 1995) combined with Edvardsson et al.'s earlier identification of 51 Peg as a NaMgAl star highlighted the group's potential importance. Our new analysis, which uses new spectra of higher resolution and better wavelength coverage than the analysis of Edvardsson et al., shows that the Na, Mg and Al abundances of the NaMgAl stars are indistinguishable from those of non-NaMgAl stars with otherwise similar properties. The group thus appears to be spurious.Our study, which includes 51 Peg, also provides the most complete set of abundances for this star available to date. The new Fe abundance, [Fe/H] = +0.20 +- 0.07, of 51 Peg confirms earlier measurements of its metal richness. Abundances for 19 other elements, including C, N and O, reveal a fairly uniform enrichment similar to that of Fe and show no evidence of abnormality compared to other metal rich stars of similar spectral type.
|
|
| 20. |
- Van Eck, Sophie, et al.
(författare)
-
A grid of MARCS model atmospheres for late-type stars II. S stars and their properties
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
-
Tidskriftsartikel (refereegranskat)abstract
- S-type stars are late-type giants whose atmospheres are enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing asymptotic giant branch. A grid of MARCS model atmospheres has been computed for S stars, covering the range 2700 <= T-eff (K) <= 4000, 0.50 <= C/O less than or similar to 0.99, 0 <= log g <= 5, [Fe/H] = 0., -0.5 dex, and [s/Fe] = 0, 1, and 2 dex (where the latter quantity refers to the global overabundance of s-process elements). The MARCS models make use of a new ZrO line list. Synthetic spectra computed from these models are used to derive photometric indices in the Johnson and Geneva systems, as well as TiO and ZrO band strengths. A method is proposed to select the model best matching any given S star, a non-trivial operation since the grid contains more than 3500 models covering a five-dimensional parameter space. The method is based on the comparison between observed and synthetic photometric indices and spectral band strengths, and has been applied on a vast subsample of the Henize sample of S stars. Our results confirm the old claim by Piccirillo (1980, MNRAS, 190, 441) that ZrO bands in warm S stars (T-eff > 3200 K) are not caused by the C /O ratio being close to unity, as traditionally believed, but rather by some Zr overabundance. The TiO and ZrO band strengths, combined with V - K and J - K photometric indices, are used to select T-eff, C/O, [Fe/H] and [s/Fe]. The Geneva U - B1 and B2 - V1 indices (or any equivalent) are good at selecting the gravity. The defining spectral features of dwarf S stars are outlined, but none is found among the Henize S stars. More generally, it is found that, at T-eff = 3200 K, a change of C/O from 0.5 to 0.99 has a strong impact on V - K (2 mag). Conversely, a range of 2 mag in V - K corresponds to a 200 K shift along the (T-eff, V - K) relationship (for a fixed C/O value). Hence, the use of a (T-eff, V - K) calibration established forMstars will yield large errors for S stars, so that a specific calibration must be used, as provided in the present paper. Using the atmospheric parameters derived by our method for the sample of Henize S stars, we show that the extrinsic-intrinsic dichotomy among S stars reveals itself very clearly as a bimodal distribution in the e ff ective temperatures. Moreover, the increase of s-process element abundances with increasing C/O ratios and decreasing temperatures is apparent among intrinsic stars, confirming theoretical expectations.
|
|
| 21. |
- van Eck, S., et al.
(författare)
-
A Grid of MARCS Model Atmospheres for S Stars
- 2011
-
Ingår i: Why Galaxies Care about AGB Stars II.
-
Konferensbidrag (refereegranskat)abstract
- S-type stars are late-type giants whose atmospheres are enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. A large grid of S-star model atmospheres has been computed covering the range 2700 \le T$_eff$(K) \le 4000 with 0.5 \le C/O \le 0.99. ZrO and TiO band strength indices as well as VJHKL photometry are needed to disentangle T$_eff$, C/O and [s/Fe]. A \ldquobest-model finding tool\rdquo has been developed using a set of well-chosen indices and checked against photometry as well as low- and high-resolution spectroscopy. It is found that applying M-star model atmospheres (i.e., with a solar C/O ratio) to S stars can lead to errors in T$_eff$ up to 400 K. We constrain the parameter space occupied by the S stars of the vast Henize sample in terms of T$_eff$, [C/O] and [s/Fe].
|
|
| 22. |
- Van Eck, Sophie, et al.
(författare)
-
A Grid of MARCS Model Atmospheres for S Stars
- 2011
-
Ingår i: Astronomical Society of the Pacific, Conference Series, Volume 445. ; , s. 71-75
-
Konferensbidrag (refereegranskat)abstract
- S-type stars are late-type giants whose atmosphere is enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. A large grid of S-star model atmospheres has been computed covering the range 2700 < Teff < 4000 K with 0.5 < C/O < 0.99. ZrO and TiO band strength indices as well as VJHKL photometry are needed to disentangle Teff, C/O and [s/Fe]. A "best-model finding tool" was developed using a set of well-chosen indices and checked against photometry as well as low- and high-resolution spectroscopy. It is found that applying M-star model atmospheres (i.e., with a solar C/O ratio) to S stars can lead to errors on Teff up to 400K. We constrain the parameter space occupied by S stars of the vast sample of Henize stars in terms of Teff, [C/O] and [s/Fe].
|
|
| 23. |
- Van Eck, S., et al.
(författare)
-
A grid of S stars MARCS model atmospheres
- 2011
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 328, s. 012009-
-
Tidskriftsartikel (refereegranskat)abstract
- S stars are cool stars of temperatures similar to those of M giants, but their atmospheres are enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing AGB. Despite numerous attempts to link phenomenological spectral classification criteria to physical parameters (T$_eff$, gravity, C/O, [s/Fe], [Fe/H]), the parameter space of S stars is poorly known and this has prevented accurate abundance analysis of S stars until now. Here we present a large grid of S-star model atmospheres. ZrO and TiO band strength indices as well as VJHKL photometry are needed to disentangle the effective temperature, C/O and [s/Fe]. The stellar parameters derived on the basis of low-resolution spectra and photometry are shown to be fairly accurate when compared to high-resolution data of the same stars. The C/O ratio of S stars is found to be between the solar value (0.5) and 0.99, and not 1 as often claimed in the literature. Consistently with stellar evolution expectations, the C/O ratio increases as the effective temperature decreases.
|
|
| 24. |
- VandenBerg, Don A., et al.
(författare)
-
A Constraint on Zsolar from Fits of Isochrones to the Color-Magnitude Diagram of M67
- 2007
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 666:2, s. L105-L108
-
Tidskriftsartikel (refereegranskat)abstract
- The mass at which a transition is made between stars that have radiative or convective cores throughout the core H burning phase is a fairly sensitive function of Z (particularly, the CNO abundances). As a consequence, the ~4 Gyr, open cluster M67 provides a constraint on Zsolar (and the solar heavy-element mixture) because (1) high-resolution spectroscopy indicates that this system has virtually the same metal abundances as the Sun, and (2) its turnoff stars have masses just above the lower limit for sustained core convection on the main sequence. In this study, evolutionary tracks and isochrones using the latest MARCS model atmospheres as boundary conditions have been computed for 0.6-1.4 Msolar on the assumption of a metals mix (implying Zsolar~0.0125) based on the solar abundances derived by M. Asplund and collaborators using 3D model atmospheres. These calculations do not predict a turnoff gap where one is observed in M67. No such difficulty is found if the analysis uses isochrones for Zsolar=0.0165, assuming the Grevesse and Sauval mix of heavy elements. Our findings, like the inferences from helioseismology, indicate a problem with the abundances of Asplund and collaborators. However, it is possible that low-Z models with diffusive processes taken into account will be less problematic.
|
|
| 25. |
- Vandenberg, Don A., et al.
(författare)
-
On Stellar Models with Blanketed Atmospheres as Boundary Conditions
- 2007
-
Ingår i: Stellar Populations as Building Blocks of Galaxies. ; , s. 23-27
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The impact on the predicted Teff scale of using the latest MARCS model atmospheres, instead of a fixed atmospheric structure (e.g., the gray T–τ relation) is examined. The former were fitted to stellar interior models at both the photosphere and at τ = 100 to determine the sensitivity of evolutionary tracks and isochrones for [Fe/H] = 0.0 and −2.0 to the chosen fitting point. In the case of solar abundances, the Teff of the giant branch varied by up to 100–150 K, depending on how the outer layers were treated. Much smaller variations were found for metal-poor giants (or main-sequence stars). Interestingly, models for the low solar Z favored by Asplund et al. (Z=0.0125) were unable to reproduce the gap near the turnoff in the C-M diagram of the old open cluster M 67, in contrast to models that assume Z=0.0188.
|
|
| 26. |
- VandenBerg, Don A., et al.
(författare)
-
On the use of blanketed atmospheres as boundary conditions for stellar evolutionary models
- 2008
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 675:1, s. 746-763
-
Tidskriftsartikel (refereegranskat)abstract
- Stellarmodels have been computed for stars having [Fe/H] = 0.0 (assuming both the Grevesse & Sauval and Asplund et al. heavy-element mixtures) and -2.0 to determine the effects on the predicted T-eff scale of using boundary conditions derived from the latest MARCS model atmospheres. The latter were fitted in a fully consistent way to the interior models at the photosphere and at tau = 100: the resultant evolutionary sequences on the H-R diagram were found to be nearly independent of the chosen fitting point. Tracks were also computed in which the pressure at T = T-eff was obtained by integrating the hydrostatic equation together with either the classical gray T(tau, T-eff) relation or that derived by Krishna Swamy from an empirical solar atmosphere. Due to the effects of differences in the solar-calibrated values of the mixing-length parameter, alpha(MLT), very similar tracks were obtained for the different treatments of the atmosphere, except at solar abundances, where the models based on the Krishna Swamy T(tau, T-eff) relationship predicted similar to 150 K hotter giant branches than the others, in good agreement with the inferred temperatures of giants in the open cluster M67 from recent (V - K) -T-eff relations. Tracks that used new "scaled solar, differentially corrected'' MARCS atmospheres were found to agree well with those that employed the Krishna Swamy T(tau, T-eff) relationship, independently of the assumed metal abundance. (Gray atmospheres are quite different from MARCS models.) Fits of isochrones for [Fe/H] = -2.0 to the CMD of the globular cluster M68, as well as the possibility that alpha(MLT) varies with stellar parameters, are also discussed.
|
|
| 27. |
- Önehag, Anna, et al.
(författare)
-
Calibration of Stromgren uvby-H beta photometry for late-type stars - a model atmosphere approach
- 2009
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 498:2, s. 527-542
-
Tidskriftsartikel (refereegranskat)abstract
- Context. The use of model atmospheres for deriving stellar fundamental parameters, such as T-eff, log g, and [Fe/H], will increase as we find and explore extreme stellar populations where empirical calibrations are not yet available. Moreover, calibrations for upcoming large satellite missions of new spectrophotometric indices, similar to the uvby-H beta system, will be needed. Aims. We aim to test the power of theoretical calibrations based on a new generation of MARCS models by comparisons with observational photomteric data. Methods. We calculated synthetic uvby-H beta colour indices from synthetic spectra. A sample of 367 field stars, as well as stars in globular clusters, is used for a direct comparison of the synthetic indices versus empirical data and for scrutinizing the possibilities of theoretical calibrations for temperature, metallicity, and gravity. Results. We show that the temperature sensitivity of the synthetic (b-y) colour is very close to its empirical counterpart, whereas the temperature scale based upon H beta shows a slight offset. The theoretical metallicity sensitivity of the m(1) index (and for G-type stars its combination with c(1)) is somewhat higher than the empirical one, based upon spectroscopic determinations. The gravity sensitivity of the synthetic c(1) index shows satisfactory behaviour when compared to obervations of F stars. For stars cooler than the sun, a deviation is significant in the c(1)-(b-y) diagram. The theoretical calibrations of (b-y), (v-y), and c(1) seem to work well for Pop II stars and lead to effective temperatures for globular cluster stars supporting recent claims that atomic diffusion occurs in stars near the turnoff point of NGC 6397. Conclusions. Synthetic colours of stellar atmospheres can indeed be used, in many cases, to derive reliable fundamental stellar parameters. The deviations seen when compared to observational data could be due to incomplete linelists but are possibly also due to the effects of assuming plane-parallell or spherical geometry and LTE.
|
|
| 28. |
- Andrae, R., et al.
(författare)
-
Gaia Data Release 3 : Analysis of the Gaia BP/RP spectra using the General Stellar Parameterizer from Photometry
- 2023
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 674
-
Tidskriftsartikel (refereegranskat)abstract
- Context: The astrophysical characterisation of sources is among the major new data products in the third Gaia Data Release (DR3). In particular, there are stellar parameters for 471 million sources estimated from low-resolution BP /RP spectra.Aims: We present the General Stellar Parameterizer from Photometry (GSP-Phot), which is part of the astrophysical parameters inference system (Apsis). GSP-Phot is designed to produce a homogeneous catalogue of parameters for hundreds of millions of single non-variable stars based on their astrometry, photometry, and low-resolution BP/RP spectra. These parameters are effective temperature, surface gravity, metallicity, absolute MG magnitude, radius, distance, and extinction for each star.Methods: GSP-Phot uses a Bayesian forward-modelling approach to simultaneously fit the BP /RP spectrum, parallax, and apparent G magnitude. A major design feature of GSP-Phot is the use of the apparent flux levels of BP /RP spectra to derive, in combination with isochrone models, tight observational constraints on radii and distances. We carefully validate the uncertainty estimates by exploiting repeat Gaia observations of the same source.Results: The data release includes GSP-Phot results for 471 million sources with G < 19. Typical differences to literature values are 110K for T-eff and 0.2-0.25 for log g, but these depend strongly on data quality. In particular, GSP-Phot results are significantly better for stars with good parallax measurements (pi/sigma(pi) > 20), mostly within 2 kpc. Metallicity estimates exhibit substantial biases compared to literature values and are only useful at a qualitative level. However, we provide an empirical calibration of our metallicity estimates that largely removes these biases. Extinctions A(0) and A(BP) show typical di fferences from reference values of 0.07-0.09 mag. MCMC samples of the parameters are also available for 95% of the sources.Conclusions: GSP-Phot provides a homogeneous catalogue of stellar parameters, distances, and extinctions that can be used for various purposes, such as sample selections (OB stars, red giants, solar analogues etc.). In the context of asteroseismology or ground-based interferometry, where targets are usually bright and have good parallax measurements, GSP-Phot results should be particularly useful for combined analysis or target selection.
|
|
| 29. |
|
|
| 30. |
- Babusiaux, C., et al.
(författare)
-
Observational Hertzsprung-Russell diagrams
- 2018
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 616
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented. Aims. We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. Methods. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. Results. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. Conclusions. Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD-based studies.
|
|
| 31. |
- Baxter, Rebecca, et al.
(författare)
-
The thriving of older people assessment scale : Psychometric evaluation and short‐form development
- 2019
-
Ingår i: Journal of Advanced Nursing. - : Wiley. - 0309-2402 .- 1365-2648. ; 75:12, s. 3831-3843
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: To evaluate the psychometric properties and performance of the 32‐item Thriving of Older People Assessment Scale (TOPAS) and to explore reduction into a short‐form.Background: The 32‐item TOPAS has been used in studies of place‐related well‐being as a positive measure in long‐term care to assess nursing home resident thriving; however, item redundancy has not previously been explored.Design: Cross‐sectional.Method: Staff members completed the 32‐item TOPAS as proxy‐raters for a random sample of Swedish nursing home residents (N = 4,831) between November 2013 and September 2014. Reliability analysis, exploratory factor analysis and item response theory‐based analysis were undertaken. Items were systematically identified for reduction using statistical and theoretical analysis. Correlation testing, means comparison and model fit evaluation confirmed scale equivalence.Results: Psychometric properties of the 32‐item TOPAS were satisfactory and several items were identified for scale reduction. The proposed short‐form TOPAS exhibited a high level of internal consistency (α=0.90) and strong correlation (r=0.98) to the original scale, while also retaining diversity among items in terms of factor structure and item difficulties.Conclusion: The 32‐item and short‐form TOPAS' indicated sound validity and reliability to measure resident thriving in the nursing home context.Impact: There is a lack of positive life‐world measures for use in nursing homes. The short‐form TOPAS indicated sound validity and reliability to measure resident thriving, providing a feasible measure with enhanced functionality for use in aged care research, assessments and care planning for health promoting purposes in nursing homes.
|
|
| 32. |
- Björk, Sabine, et al.
(författare)
-
Exploring the prevalence and variance of cognitive impairment, pain, neuropsychiatric symptoms and ADL dependency among persons living in nursing homes : a cross-sectional study
- 2016
-
Ingår i: BMC Geriatrics. - : BioMed Central. - 1471-2318 .- 1471-2318. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Earlier studies in nursing homes show a high prevalence of cognitive impairment, dependency in activities of daily living (ADL), pain, and neuropsychiatric symptoms among residents. The aim of this study was to explore the prevalence of the above among residents in a nationally representative sample of Swedish nursing homes, and to investigate whether pain and neuropsychiatric symptoms differ in relation to gender, cognitive function, ADL-capacity, type of nursing-home unit and length of stay. Methods: Cross-sectional data from 188 randomly selected nursing homes were collected. A total of 4831 residents were assessed for cognitive and ADL function, pain and neuropsychiatric symptoms. Data were analysed using descriptive statistics and the chi-square test. Results: The results show the following: the prevalence of cognitive impairment was 67 %, 56 % of residents were ADL-dependent, 48 % exhibited pain and 92 % exhibited neuropsychiatric symptoms. The prevalence of pain did not differ significantly between male and female residents, but pain was more prevalent among cognitively impaired and ADL-dependent residents. Pain prevalence was not significantly different between residents in special care units for people with dementia (SCU) and general units, or between shorter-and longer-stay residents. Furthermore, the prevalence of neuropsychiatric symptoms did not differ significantly between male and female residents, between ADL capacities or in relation to length of stay. However, residents with cognitive impairment and residents in SCUs had a significantly higher prevalence of neuropsychiatric symptoms than residents without cognitive impairment and residents in general units. Conclusions: The prevalence rates ascertained in this study could contribute to a greater understanding of the needs of nursing-home residents, and may provide nursing home staff and managers with trustworthy assessment scales and benchmark values for further quality assessment purposes, clinical development work and initiating future nursing assessments.
|
|
| 33. |
- Bolse, Kärstin, et al.
(författare)
-
Life situation related to the ICD implantation : self-reported uncertainty and satisfaction in Swedish and US samples
- 2002
-
Ingår i: European Journal of Cardiovascular Nursing. - Amsterdam : Elsevier. - 1474-5151 .- 1873-1953. ; 1:4, s. 243-251
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to describe changes in the life situation related to the ICD implantation of Swedish and US samples with regard to uncertainty and satisfaction. The life situation was measured by reference to the uncertainty caused by the condition and satisfaction with the life situation. Inferential statistics were used to analyse changes within and between the Swedish and US samples. Uncertainty showed a statistically significant difference between the Swedish and US samples before as well as after the ICD implantation. A higher level of uncertainty was indicated for the US sample prior to the ICD implantation and for the Swedish sample following the implantation. In the Swedish sample, satisfaction with life showed a statistically significant difference within the socio-economic domain, indicating a higher degree of satisfaction 3 months after implantation. Satisfaction within the domains of health and functioning, socio-economics and psychological-spiritual showed a statistically significant difference between the Swedish and US samples both before and after ICD implantation, indicating a higher degree of satisfaction in the US sample. The previous study shows that the ICD-patient's life situation is changed after the implantation and that it is necessary to provide the patient with information and education based on their own preconditions. The fact that US sample was investigated at a later stage after ICD implantation than the Swedish sample may have influenced the results of the study.
|
|
| 34. |
- Brown, A. G. A., et al.
(författare)
-
Gaia Data Release 1 Summary of the astrometric, photometric, and survey properties
- 2016
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595
-
Tidskriftsartikel (refereegranskat)abstract
- Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of similar to 3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr(-1) for the proper motions. A systematic component of similar to 0.3 mas should be added to the parallax uncertainties. For the subset of similar to 94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr(-1). For the secondary astrometric data set, the typical uncertainty of the positions is similar to 10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to similar to 0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data.
|
|
| 35. |
- Brown, A. G. A., et al.
(författare)
-
Gaia Data Release 2 Summary of the contents and survey properties
- 2018
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 616
-
Tidskriftsartikel (refereegranskat)abstract
- Context. We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. Aims. A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. Methods. The raw data collected with the Gaia instruments during the first 22 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into this second data release, which represents a major advance with respect to Gaia DR1 in terms of completeness, performance, and richness of the data products. Results. Gaia DR2 contains celestial positions and the apparent brightness in G for approximately 1.7 billion sources. For 1.3 billion of those sources, parallaxes and proper motions are in addition available. The sample of sources for which variability information is provided is expanded to 0 : 5 million stars. This data release contains four new elements: broad-band colour information in the form of the apparent brightness in the G(BP) (330-680 nm) and G(RP) (630-1050 nm) bands is available for 1.4 billion sources; median radial velocities for some 7 million sources are presented; for between 77 and 161 million sources estimates are provided of the stellar effective temperature, extinction, reddening, and radius and luminosity; and for a pre-selected list of 14 000 minor planets in the solar system epoch astrometry and photometry are presented. Finally, Gaia DR2 also represents a new materialisation of the celestial reference frame in the optical, the Gaia-CRF2, which is the first optical reference frame based solely on extragalactic sources. There are notable changes in the photometric system and the catalogue source list with respect to Gaia DR1, and we stress the need to consider the two data releases as independent. Conclusions. Gaia DR2 represents a major achievement for the Gaia mission, delivering on the long standing promise to provide parallaxes and proper motions for over 1 billion stars, and representing a first step in the availability of complementary radial velocity and source astrophysical information for a sample of stars in the Gaia survey which covers a very substantial fraction of the volume of our galaxy.
|
|
| 36. |
- Brown, A. G.A., et al.
(författare)
-
Gaia Early Data Release 3: Summary of the contents and survey properties
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 1432-0746 .- 0004-6361. ; 649
-
Tidskriftsartikel (refereegranskat)abstract
- Context. We present the early installment of the third Gaia data release, Gaia EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities from Gaia DR2. Aims. A summary of the contents of Gaia EDR3 is presented, accompanied by a discussion on the differences with respect to Gaia DR2 and an overview of the main limitations which are present in the survey. Recommendations are made on the responsible use of Gaia EDR3 results. Methods. The raw data collected with the Gaia instruments during the first 34 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium and turned into this early third data release, which represents a major advance with respect to Gaia DR2 in terms of astrometric and photometric precision, accuracy, and homogeneity. Results. Gaia EDR3 contains celestial positions and the apparent brightness in G for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (GBP - GRP) colour are also available. The passbands for G, GBP, and GRP are provided as part of the release. For ease of use, the 7 million radial velocities from Gaia DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of Gaia DR3. Finally, Gaia EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the Gaia-CRF3, which is based solely on extragalactic sources. The creation of the source list for Gaia EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for Gaia DR2, but it does feature new sources and there are some notable changes. The source list will not change for Gaia DR3. Conclusions. Gaia EDR3 represents a significant advance over Gaia DR2, with parallax precisions increased by 30 per cent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30-40% for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for G, GBP, and GRP is valid over the entire magnitude and colour range, with no systematics above the 1% level © ESO 2021.
|
|
| 37. |
|
|
| 38. |
- Clementini, G., et al.
(författare)
-
Testing parallaxes with local Cepheids and RR Lyrae stars
- 2017
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 605
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the HIPPARCOS and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS.Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with sigma(omega)/omega < 0 : 5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with sigma(omega)/omega 0 : 5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with sigma(omega)/omega < 0 : 5). The new relations were computed using multi- band (V; I; J; K-s) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL; PW; PLZ, and MV [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods.Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the HIPPARCOS measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive.Conclusions. TGAS parallaxes bring a significant added value to the previous HIPPARCOS estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018.
|
|
| 39. |
- Corneliusson, Laura, et al.
(författare)
-
Residing in sheltered housing versus ageing in place : population characteristics, health status and social participation
- 2019
-
Ingår i: Health & Social Care in the Community. - : John Wiley & Sons. - 0966-0410 .- 1365-2524. ; 27:4, s. E313-E322
-
Tidskriftsartikel (refereegranskat)abstract
- Sheltered housing is a housing model that provides accessible apartments with elevated social possibilities for older people, which is expected to increase resident health and independence, reducing the need for care. As previous research on sheltered housing is scarce, the aim of this study was to explore the characteristics, health status and social participation of older people living in sheltered housing, compared to ageing in place. The study utilised baseline data from a matched cohort study survey on a nationally representative total population of residents in all sheltered housings in Sweden, and a matched control group (n = 3,805). The data collection took place between October 2016 and January 2017. The survey assessed functional capability using the Katz ADL and Lawton IADL scale, self-rated health using the EQ5D scale, and depressive mood using the GDS-4 scale. Descriptive statistics, frequencies, mean scores, independent t tests, p-values and effect sizes were utilised to compare the two groups. The results of the study show that older people living in sheltered housing, compared to ageing in place, had lower self-reported health (M = 64.68/70.08, p = <0.001), lower self-reported quality of life (M = 0.73/0.81, p = <0.001), lower functional status concerning activities of daily living (M = 5.19/5.40, p = <0.001), lower functional status concerning instrumental activities of daily living (M = 4.98/5.42 p = <0.001,), and higher probability of depressive mood (M = 0.80/0.58, p = <0.001). The results imply that residents in sheltered housing may have more care needs than those ageing in place. Further longitudinal comparative studies are needed to explore the impact residence in sheltered housing has on resident health and well-being.
|
|
| 40. |
- Corneliusson, Laura, et al.
(författare)
-
Well‐being and Thriving in Sheltered Housing versus Ageing in Place : Results from the U‐Age Sheltered Housing Study
- 2020
-
Ingår i: Journal of Advanced Nursing. - : John Wiley & Sons. - 0309-2402 .- 1365-2648. ; 73:3, s. 856-866
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: To explore to what extent type of residence (sheltered housing or ageing in place) contributes to thriving and well-being in older adults, when controlling for age, sex, living alone, being a widow and adjusting for functional status, self-rated health, and depressive mood.Design: A matched cohort study.Methods A self-report survey was sent out to a total population of residents in all sheltered housings in Sweden and a matched control group ageing in place (N = 3,805). The data collection took place between October 2016-January 2017.Results: The interaction analyses related to thriving showed that with increasing level of depressive mood and decreasing levels of self-rated health and functional status, those residing in sheltered housing generally reported higher levels of thriving, as compared with those ageing in place. Well-being was not found to be significantly associated with type of accommodation.Conclusion: There may be features in sheltered housing that are associated with resident thriving especially among individuals with impairments of function, health or mood, although further studies are required to identify these specific features.Impact: This study informs staff and policymakers about thriving and well-being in sheltered housing accommodations. These findings may be used to further the development of sheltered housing accommodations.
|
|
| 41. |
- Creevey, O. L., et al.
(författare)
-
Gaia Data Release 3 : Astrophysical parameters inference system (Apsis). I. Methods and content overview
- 2023
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 674
-
Tidskriftsartikel (refereegranskat)abstract
- Gaia Data Release 3 contains a wealth of new data products for the community. Astrophysical parameters are a major component of this release, and were produced by the Astrophysical parameters inference system (Apsis) within the Gaia Data Processing and Analysis Consortium (DPAC). The aim of this paper is to describe the overall content of the astrophysical parameters in Gaia DR3 and how they were produced. In Apsis, we use the mean BP /RP and mean RVS spectra along with astrometry and photometry, and we derive the following parameters: source classification and probabilities for 1.6 billion objects; interstellar medium characterisation and distances for up to 470 million sources, including a 2D total Galactic extinction map; 6 million redshifts of quasar candidates; 1.4 million redshifts of galaxy candidates; and an analysis of 50 million outlier sources through an unsupervised classification. The astrophysical parameters also include many stellar spectroscopic and evolutionary parameters for up to 470 million sources. These comprise T-eff, log g, and [M /H] (470 million using BP /RP, 6 million using RVS), radius (470 million), mass (140 million), age (120 million), chemical abundances (up to 5 million), diffuse interstellar band analysis (0.5 million), activity indices (2 million), H ff equivalent widths (200 million), and further classification of spectral types (220 million) and emission-line stars (50 000). This paper is the first in a series of three papers, and focusses on describing the global content of the parameters in Gaia DR3. The accompanying Papers II and III focus on the validation and use of the stellar and non-stellar products, respectively. This catalogue is the most extensive homogeneous database of astrophysical parameters to date, and is based uniquely on Gaia data. It will only be superseded by Gaia Data Release 4, and will therefore remain a key reference over the next four years, providing astrophysical parameters independent of other ground- and space-based data.
|
|
| 42. |
- de Jong, R. S., et al.
(författare)
-
4MOST : Project overview and information for the First Call for Proposals
- 2019
-
Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
|
|
| 43. |
- de Jong, Roelof S., et al.
(författare)
-
4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
-
Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
-
Konferensbidrag (refereegranskat)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
|
|
| 44. |
- Delchambre, L., et al.
(författare)
-
Apsis. III. Non-stellar content and source classification
- 2023
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 674
-
Tidskriftsartikel (refereegranskat)abstract
- Context: As part of the third Gaia Data Release, we present the contributions of the non-stellar and classification modules from the eighth coordination unit (CU8) of the Data Processing and Analysis Consortium, which is responsible for the determination of source astrophysical parameters using Gaia data. This is the third in a series of three papers describing the work done within CU8 for this release.Aims: For each of the five relevant modules from CU8, we summarise their objectives, the methods they employ, their performance, and the results they produce for Gaia DR3. We further advise how to use these data products and highlight some limitations.Methods: The Discrete Source Classifier (DSC) module provides classification probabilities associated with five types of sources: quasars, galaxies, stars, white dwarfs, and physical binary stars. A subset of these sources are processed by the Outlier Analysis (OA) module, which performs an unsupervised clustering analysis, and then associates labels with the clusters to complement the DSC classification. The Quasi Stellar Object Classifier (QSOC) and the Unresolved Galaxy Classifier (UGC) determine the redshifts of the sources classified as quasar and galaxy by the DSC module. Finally, the Total Galactic Extinction (TGE) module uses the extinctions of individual stars determined by another CU8 module to determine the asymptotic extinction along all lines of sight for Galactic latitudes |b| > 5 degrees.Results: Gaia DR3 includes 1591 million sources with DSC classifications; 56 million sources to which the OA clustering is applied; 1.4 million sources with redshift estimates from UGC; 6.4 million sources with QSOC redshift; and 3.1 million level 9 HEALPixes of size 0 :013 deg(2) where the extinction is evaluated by TGE.Conclusions: Validation shows that results are in good agreement with values from external catalogues; for example 90% of the QSOC redshifts have absolute error lower than 0:1 for sources with empty warning flags, while UGC redshifts have a mean error of 0:008 +/- 0:037 if evaluated on a clean set of spectra. An internal validation of the OA results further shows that 30 million sources are located in high confidence regions of the clustering map.
|
|
| 45. |
- Edvardsson, Bengt
(författare)
-
Abundances in the Galactic Disk
- 2002
-
Ingår i: Cosmic chemical evolution. Proceedings of the 187th Symposium of the International Astronomical Union. - : Dordrecht: Kluwer Academic Publishers. - 1402004486 ; 187, s. 91-96
-
Recension (övrigt vetenskapligt/konstnärligt)abstract
- I will constrain myself to discussion of abundances and abundance gradients in the local Galactic Disk and continue with the scatter in these abundances, presently and historically.
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
- Edvardsson, Bengt
(författare)
-
Atenolol in the prophylaxis of chronic migraine: a 3-month open-label study.
- 2013
-
Ingår i: SpringerPlus. - : Springer Science and Business Media LLC. - 2193-1801. ; 2:Sep 22
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic migraine (CM) is a type of chronic daily headache. CM presents a challenge to primary care physicians and neurologists. Any new treatment showing efficiency would therefore be of great importance. Atenolol together with other beta-blockers is a first-line choice in episodic migraine prophylaxis. Clinical findings support the efficacy of atenolol in doses of 50 to 200 mg/day.
|
|
