| 41. |
- Christleib, Norbert, et al.
(author)
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4MOST Consortium Survey 2: The Milky Way Halo High-Resolution Survey
- 2019
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In: Messenger. - 0722-6691. ; 175, s. 26-29
-
Journal article (other academic/artistic)abstract
- We will study the formation history of the Milky Way, and the earliest phases of its chemical enrichment, with a sample of more than 1.5 million stars at high galactic latitude. Elemental abundances of up to 20 elements with a precision of better than 0.2 dex will be derived for these stars. The sample will include members of kinematically coherent substructures, which we will associate with their possible birthplaces by means of their abundance signatures and kinematics, allowing us to test models of galaxy formation. Our target catalogue is also expected to contain 30 000 stars at a metallicity of less than one hundredth that of the Sun. This sample will therefore be almost a factor of 100 larger than currently existing samples of metal-poor stars for which precise elemental abundances are available (determined from high-resolution spectroscopy), enabling us to study the early chemical evolution of the Milky Way in unprecedented detail.
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| 42. |
- Church, Ross, et al.
(author)
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Coordinates and 2MASS and OGLE identifications for all stars in Arp's 1965 finding chart for Baade's Window
- 2011
-
In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 529
-
Journal article (peer-reviewed)abstract
- Aims. We seek to provide 2MASS and OGLE identifications and coordinates for all stars in the finding chart published by Arp (1965, ApJ, 141, 43). This chart covers the low extinction area around NGC 6522, also known as Baade's window, at coordinates (l, b) = (1.02, -3.92). Methods. A cross correlation, using numerical techniques, was performed between a scan of the original finding chart from Arp and 2MASS and OGLE-II images and stellar coordinates. Results. We provide coordinates for all stars in Arp's finding chart and 2MASS and OGLE identifications wherever possible. Two identifications in quadrant II do not appear in the original finding chart.
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| 43. |
- Cirasuolo, M., et al.
(author)
-
MOONS: the Multi-Object Optical and Near-infrared Spectrograph for the VLT
- 2014
-
In: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147, s. 91470-91470
-
Conference paper (peer-reviewed)abstract
- MOONS (the Multi-Object Optical and Near-infrared Spectrograph) has been selected by ESO as a third-generation instrument for the Very Large Telescope (VLT). The light grasp of the large collecting area offered by the VLT (8.2m diameter), combined with the large multiplex and wavelength coverage (optical to near-IR: 0.8 -1.8 mu m) of MOONS will provide the European astronomical community with a powerful, unique instrument able to pioneer a wide range of Galactic, extragalactic and cosmological studies, and it will provide crucial follow-up for major facilities such as Gaia, VISTA, Euclid and LSST. MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, from stars in our Milky Way, through the redshift desert, and up to the epoch of very first galaxies and reionization of the Universe at redshifts of z > 8-9, just a few million years after the Big Bang. From five years of observations MOONS will provide high-quality spectra for > 3M stars in our Galaxy and the Local Group, and for 1-2M galaxies at z > 1 (for an SDSS-like survey), promising to revolutionize our understanding of the Universe. The baseline design consists of similar to 1000 fibres, deployable over a field-of-view of similar to 500 arcmin(2), the largest patrol field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8 -1.8 mu m with two spectral resolving powers: in the medium-resolution mode (R similar to 4,000-6,000) the entire wavelength range is observed simultaneously, while the high-resolution mode will cover three selected sub-regions simultaneously: one region with R similar to 8,000 near the Ca II triplet to measure stellar radial velocities, and two regions at R similar to 20,000 (one in each of the J- and H-bands), for precision measurements of chemical abundances.
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| 44. |
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| 45. |
- de Jong, Roelof S., et al.
(author)
-
4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
-
In: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
-
Conference paper (peer-reviewed)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].
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| 46. |
- De Jong, Roelof S., et al.
(author)
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4MOST : The 4-metre Multi-Object Spectroscopic Telescope project at preliminary design review
- 2016
-
In: Ground-Based and Airborne Instrumentation for Astronomy VI. - : SPIE. - 1996-756X .- 0277-786X. - 9781510601956 ; 9908
-
Conference paper (peer-reviewed)abstract
- We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R∼20,000) and two medium resolution (R∼5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a 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. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey.
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| 47. |
- Faria, Daniel, et al.
(author)
-
The Age of the Metal-Rich Globular Cluster NGC 6352
- 2002
-
In: Observed HR Diagrams and Stellar Evolution, ASP Conference Proceedings, Vol. 274. Edited by Thibault Lejeune and João Fernandes. ISBN: 1-58381-116-8. San Francisco: Astronomical Society of the Pacific, 2002., p.373. ; 274, s. 373-376
-
Conference paper (peer-reviewed)
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| 48. |
- Faria, Daniel, et al.
(author)
-
The usage of Stromgren photometry in studies of local group dwarf spheroidal galaxies - Application to Draco: a new catalogue of Draco members and a study of the metallicity distribution function and radial gradients
- 2007
-
In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 465:2, s. 28-357
-
Journal article (peer-reviewed)abstract
- Aims. In this paper we demonstrate how Stromgren uvby photometry can be efficiently used to: 1. identify red giant branch stars that are members in a dwarf spheroidal galaxy; 2. derive age-independent metallicities for the same stars and quantify the associated errors. Methods. Stromgren uvby photometry in a 11 x 22 arcmin field centered on the Draco dwarf spheroidal galaxy was obtained using the Isaac Newton Telescope on La Palma. Members of the Draco dSph galaxy were identified using the surface gravity sensitive c(1) index which discriminates between red giant and dwarf stars. Thus enabling us to distinguish the (red giant branch) members of the dwarf spheroidal galaxy from the foreground dwarf stars in our galaxy. The method is evaluated through a comparison of our membership list with membership classifications in the literature based on radial velocities and proper motions. The metallicity sensitive m(1) index was used to derive individual and age-independent metallicities for the members of the Draco dSph galaxy. The derived metallicities are compared to studies based on high resolution spectroscopy and the agreement is found to be very good. Results. We present metallicities for 169 members of the red giant branch in the Draco dwarf spheroidal galaxy (the largest sample to date). The metallicity distribution function for the Draco dSph galaxy shows a mean [Fe/H] = -1.74 dex with a spread of 0.24 dex. The correlation between metallicity and colour for the stars on the red giant branch is consistent with a dominant old, and coeval population. There is a possible spatial population gradient over the field with the most metal-rich stars being more centrally concentrated than the metal-poor stars.
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| 49. |
- Feltzing, Sofia, et al.
(author)
-
A new, cleaner colour-magnitude diagram for the metal-rich globular cluster NGC 6528 and the velocity dispersion in the Galactic Bulge
- 2002
-
In: Observed HR Diagrams and Stellar Evolution: The Interplay Between Observational Constraints and Theory. - 9781583816097 ; 274, s. 294-299
-
Conference paper (peer-reviewed)abstract
- Using two epochs of observations with HST/WFPC2 we obtain the stellar proper motions for all stars in the field. The proper motion are used to separate the bulge from the cluster stars. The stellar sequences in the resulting colour-magnitude diagram (CMD) are better defined than in any previously published CMD. Using a-enhanced stellar isochrones we find NGC 6528 to have a probable age of 11 +/- 2 Gyrs, this is the first attempt to establish the ab. solute age of NGC 6528. Previous studies have only compared the fiducial ridge line for the cluster to that of other globular clusters of similar metallicities. Mainly the comparisons have been with regards to NGC 6553 and 47 Tuc. With the new metallicity determinations for individual stars in both NGC 6553 and NGC 6528 it is now clear that 47 Tuc (at -0.71 dex) has a significantly lower metallicity than NGC 6528 and NGC 6553 and is thus not a suitable comparison cluster as regards differential age determinations. A comparison with the fiducial line for NGC 6553 confirms results in earlier studies, e.g. Ortolani et al. (1995), that the two clusters indeed have very similar ages. From the measured velocities both the proper motion of the,cluster and the velocity dispersion in the Galactic Bulge are found. NGC 6528 is found to have a proper motion relative to the Galactic Bulge of < mu(l) > = 0.006 and < mu(b) > = 0.044 arcsec per century. Using stars with similar to 14 < V-555 < 19 (i.e. the red giant branch and horizontal branch) we find, for the Galactic Bulge, sigma(l) = 0.33 +/- 0.03 and sigma(b) = 0.25 +/- 0.02 arcsec per century. This give sigma(l)/sigma(b) = 1.32 +/- 0.16, consistent both with previous proper motion studies of K giants in the Galactic bulge as well as with predictions by models of the kinematics of bulge stars.
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| 50. |
- Feltzing, Sofia, et al.
(author)
-
A new, cleaner colour-magnitude diagram for the metal-rich globular cluster NGC 6528. Velocity dispersion in the Bulge, age and proper motion of NGC 6528
- 2002
-
In: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 385, s. 67-86
-
Journal article (peer-reviewed)abstract
- Using two epochs of HST/WFPC2 images of the metal-rich globular clusterNGC 6528 we derive the proper motions of the stars and use them toseparate the stars belonging to NGC 6528 from those of the Galacticbulge. The stellar sequences in the resulting colour-magnitude diagramfor the cluster are significantly better determined than in previouslypublished data. From comparison of the colour-magnitude diagram with thefiducial line for NGC 6553 from Zoccali et al. (cite{Zo01}) we concludethat the two globular clusters have the same age. Further, using alpha-enhanced stellar isochrones, NGC 6528 is found to have an age of 11+/-2 Gyr. This fitting of isochrones also give that the cluster is 7.2 kpcaway from us. From the measured velocities both the proper motion of thecluster and the velocity dispersion in the Galactic bulge are found. NGC6528 is found to have a proper motion relative to the Galactic bulge ofl > = 0.006 and b> = 0.044arcsec per century. Using stars with ~ 14 555 < 19(i.e. the red giant branch and horizontal branch) we find, for theGalactic bulge, sigma l= 0.33+/- 0.03 and sigma b=0.25+/-0.02 arcsec per century. This give sigma l/sigmab=1.32+/-0.16, consistent both with previous proper motionstudies of K giants in the Galactic bulge as well as with predictions bymodels of the kinematics of bulge stars. Based on observations with theNASA/ESA Hubble Space Telescope, obtained at the Space Telescope ScienceInstitute, which is operated by the Association of Universities forResearch in Astronomy, Inc. under NASA contract No. NAS5-26555. TablesA1, A2 and A3 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/385/67
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