| 31. |
- Hennemann, M., et al.
(författare)
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Herschel observations of embedded protostellar clusters in the Rosette molecular cloud
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L84-
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Tidskriftsartikel (refereegranskat)abstract
- The Herschel OB young stellar objects survey (HOBYS) has observed the Rosette molecular cloud, providing an unprecedented view of its star formation activity. These new far-infrared data reveal a population of compact young stellar objects whose physical properties we aim to characterise. We compiled a sample of protostars and their spectral energy distributions that covers the near-infrared to submillimetre wavelength range. These were used to constrain key properties in the protostellar evolution, bolometric luminosity, and envelope mass and to build an evolutionary diagram. Several clusters are distinguished including the cloud centre, the embedded clusters in the vicinity of luminous infrared sources, and the interaction region. The analysed protostellar population in Rosette ranges from 0.1 to about 15 M-circle dot with luminosities between 1 and 150 L-circle dot, which extends the evolutionary diagram from low-mass protostars into the high-mass regime. Some sources lack counterparts at near-to mid-infrared wavelengths, indicating extreme youth. The central cluster and the Phelps & Lada 7 cluster appear less evolved than the remainder of the analysed protostellar population. For the central cluster, we find indications that about 25% of the protostars classified as Class I from near-to mid-infrared data are actually candidate Class 0 objects. As a showcase for protostellar evolution, we analysed four protostars of low-to intermediate-mass in a single dense core, and they represent different evolutionary stages from Class 0 to Class I. Their mid-to far-infrared spectral slopes flatten towards the Class I stage, and the 160 to 70 mu m flux ratio is greatest for the presumed Class 0 source. This shows that the Herschel observations characterise the earliest stages of protostellar evolution in detail.
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| 32. |
- Johnston, Marston Sheldon, 1971, et al.
(författare)
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The representation of tropical upper tropospheric water in EC Earth V2
- 2012
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 39:11, s. 2713-2731
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Tidskriftsartikel (refereegranskat)abstract
- Tropical upper tropospheric humidity, clouds, and ice water content, as well as outgoing longwave radiation (OLR), are evaluated in the climate model EC Earth with the aid of satellite retrievals. The Atmospheric Infrared Sounder and Microwave Limb Sounder together provide good coverage of relative humidity. EC Earth's relative humidity is in fair agreement with these observations. CloudSat and CALIPSO data are combined to provide cloud fractions estimates throughout the altitude region considered (500-100 hPa). EC Earth is found to overestimate the degree of cloud cover above 200 hPa and underestimate it below. Precipitating and non-precipitating EC Earth ice definitions are combined to form a complete ice water content. EC Earth's ice water content is below the uncertainty range of CloudSat above 250 hPa, but can be twice as high as CloudSat's estimate in the melting layer. CERES data show that the model underestimates the impact of clouds on OLR, on average with about 9 W m(-2). Regionally, EC Earth's outgoing longwave radiation can be similar to 20 W m(-2) higher than the observation. A comparison to ERA-Interim provides further perspectives on the model's performance. Limitations of the satellite observations are emphasised and their uncertainties are, throughout, considered in the analysis. Evaluating multiple model variables in parallel is a more ambitious approach than is customary.
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| 33. |
- Justtanont, Kay, 1965, et al.
(författare)
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A HIFI preview of warm molecular gas around chi Cygni: first detection of H2O emission toward an S-type AGB star
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L6-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. A set of new, sensitive, and spectrally resolved, sub-millimeter line observations are used to probe the warm circumstellar gas around the S-type AGB star chi Cyg. The observed lines involve high rotational quantum numbers, which, combined with previously obtained lower-frequency data, make it posible to study in detail the chemical and physical properties of, essentially, the entire circumstellar envelope of chi Cyg. Methods. The data were obtained using the HIFI instrument aboard Herschel, whose high spectral resolution provides valuable information about the line profiles. Detailed, non-LTE, radiative transfer modelling, including dust radiative transfer coupled with a dynamical model, has been performed to derive the temperature, density, and velocity structure of the circumstellar envelope. Results. We report the first detection of circumstellar H2O rotational emission lines in an S-star. Using the high-J CO lines to derive the parameters for the circumstellar envelope, we modelled both the ortho-and para-H2O lines. Our modelling results are consistent with the velocity structure expected for a dust-driven wind. The derived total H2O abundance (relative to H-2) is (1.1 +/- 0.2) x 10(-5), much lower than that in O-rich stars. The derived ortho-to-para ratio of 2.1 +/- 0.6 is close to the high-temperature equilibrium limit, consistent with H2O being formed in the photosphere.
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| 34. |
- Justtanont, Kay, 1965, et al.
(författare)
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Herschel/HIFI observations of O-rich AGB stars: molecular inventory
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 537, s. Article Number: A144 -
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Spectra, taken with the heterodyne instrument, HIFI, aboard the Herschel Space Observatory, of O-rich asymptotic giant branch (AGB) stars which form part of the guaranteed time key program HIFISTARS are presented. The aim of this program is to study the dynamical structure, mass-loss driving mechanism, and chemistry of the outflows from AGB stars as a function of chemical composition and initial mass. Methods. We used the HIFI instrument to observe nine AGB stars, mainly in the H2O and high rotational CO lines. We investigate the correlation between line luminosity, line ratio and mass-loss rate, line width and excitation energy. Results. A total of nine different molecules, along with some of their isotopologues have been identified, covering a wide range of excitation temperature. Maser emission is detected in both the ortho-and para-H2O molecules. The line luminosities of ground state lines of ortho- and para-H2O, the high-J CO and NH3 lines show a clear correlation with mass-loss rate. The line ratios of H2O and NH3 relative to CO J = 6-5 correlate with the mass-loss rate while ratios of higher CO lines to the 6-5 is independent of it. In most cases, the expansion velocity derived from the observed line width of highly excited transitions formed relatively close to the stellar photosphere is lower than that of lower excitation transitions, formed farther out, pointing to an accelerated outflow. In some objects, the vibrationally excited H2O and SiO which probe the acceleration zone suggests the wind reaches its terminal velocity already in the innermost part of the envelope, i.e., the acceleration is rapid. Interestingly, for R Dor we find indications of a deceleration of the outflow in the region where the material has already escaped from the star.
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| 35. |
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| 36. |
- Marinovich, ML, et al.
(författare)
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Developing evidence-based recommendations for optimal interpregnancy intervals in high-income countries: protocol for an international cohort study
- 2019
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 9:1, s. e027941-
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Tidskriftsartikel (refereegranskat)abstract
- Short interpregnancy interval (IPI) has been linked to adverse pregnancy outcomes. WHO recommends waiting at least 2 years after a live birth and 6 months after miscarriage or induced termination before conception of another pregnancy. The evidence underpinning these recommendations largely relies on data from low/middle-income countries. Furthermore, recent epidemiological investigations have suggested that these studies may overestimate the effects of IPI due to residual confounding. Future investigations of IPI effects in high-income countries drawing from large, population-based data sources are needed to inform IPI recommendations. We aim to assess the impact of IPIs on maternal and child health outcomes in high-income countries.Methods and analysisThis international longitudinal retrospective cohort study will include more than 18 million pregnancies, making it the largest study to investigate IPI in high-income countries. Population-based data from Australia, Finland, Norway and USA will be used. Birth records in each country will be used to identify consecutive pregnancies. Exact dates of birth and clinical best estimates of gestational length will be used to estimate IPI. Administrative birth and health data sources with >99% coverage in each country will be used to identify maternal sociodemographics, pregnancy complications, details of labour and delivery, birth and child health information. We will use matched and unmatched regression models to investigate the impact of IPI on maternal and infant outcomes, and conduct meta-analysis to pool results across countries.Ethics and disseminationEthics boards at participating sites approved this research (approval was not required in Finland). Findings will be published in peer-reviewed journals and presented at international conferences, and will inform recommendations for optimal IPI in high-income countries. Findings will provide important information for women and families planning future pregnancies and for clinicians providing prenatal care and giving guidance on family planning.
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| 37. |
- Marston, C. A., et al.
(författare)
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Working together to co-produce better health : The experience of the Collaboration for Leadership in Applied Health Research and Care for Northwest London
- 2020
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Ingår i: Journal of Health Services Research and Policy. - : Sage Publications. - 1355-8196 .- 1758-1060. ; 26:1, s. 28-36
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To improve the provision of health care, academics can be asked to collaborate with clinicians, and clinicians with patients. Generating good evidence on health care practice depends on these collaborations working well. Yet such relationships are not the norm. We examine how social science research and health care improvement practice were linked through a programme designed to broker collaborations between clinicians, academics, and patients to improve health care – the UK National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care for Northwest London. We discuss the successes and challenges of the collaboration and make suggestions on how to develop synergistic relationships that facilitate co-production of social science knowledge and its translation into practice. Methods: A qualitative approach was used, including ethnographic elements and critical, reflexive dialogue between members of the two collaborating teams. Results: Key challenges and remedies were connected with the risks associated with new ways of working. These risks included differing ideas between collaborators about the purpose, value, and expectations of research, and institutional opposition. Dialogue between collaborators did not mean absence of tensions or clashes. Risk-taking was unpopular – institutions, funders, and partners did not always support it, despite simultaneously demanding ‘innovation’ in producing research that influenced practice. Conclusions: Our path was made smoother because we had funding to support the creation of a ‘potential space’ to experiment with different ways of working. Other factors that can enhance collaboration include a shared commitment to dialogical practice, a recognition of the legitimacy of different partners’ knowledge, a long timeframe to identify and resolve problems, the maintenance of an enabling environment for collaboration, a willingness to work iteratively and reflexively, and a shared end goal. © The Author(s) 2020.
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| 38. |
- Menten, K. M., et al.
(författare)
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Herschel/HIFI deepens the circumstellar NH3 enigma
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 521:1, s. Article Number: L7-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Circumstellar envelopes (CSEs) of a variety of evolved stars have been found to contain ammonia (NH3) in amounts that exceed predictions from conventional chemical models by many orders of magnitude. Aims. The observations reported here were performed in order to better constrain the NH3 abundance in the CSEs of four, quite diverse, oxygen-rich stars using the NH3 ortho J(K) = 1(0)-0(0) ground-state line. Methods. We used the Heterodyne Instrument for the Far Infrared aboard Herschel to observe the NH3 J(K) = 1(0)-0(0) transition near 572.5 GHz, simultaneously with the ortho-H2O J(Ka,Kc) = 1(1,0)-1(0,1) transition, toward VY CMa, OH 26.5+0.6, IRC+10420, and IK Tau. We conducted non-LTE radiative transfer modeling with the goal to derive the NH3 abundance in these objects' CSEs. For the last two stars, Very Large Array imaging of NH3 radio-wavelength inversion lines were used to provide further constraints, particularly on the spatial extent of the NH3-emitting regions. Results. We find remarkably strong NH3 emission in all of our objects with the NH3 line intensities rivaling those of the ground state H2O line. The NH3 abundances relative to H-2 are very high and range from 2 x 10(-7) to 3 x 10(-6) for the objects we have studied. Conclusions. Our observations confirm and even deepen the circumstellar NH3 enigma. While our radiative transfer modeling does not yield satisfactory fits to the observed line profiles, it does lead to abundance estimates that confirm the very high values found in earlier studies. New ways to tackle this mystery will include further Herschel observations of more NH3 lines and imaging with the Expanded Very Large Array.
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| 39. |
- Motte, F., et al.
(författare)
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Initial highlights of the HOBYS key program, the Herschel imaging survey of OB young stellar objects
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L77-
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Tidskriftsartikel (refereegranskat)abstract
- We present the initial highlights of the HOBYS key program, which are based on Herschel images of the Rosette molecular complex and maps of the RCW120 H II region. Using both SPIRE at 250/350/500 mu m and PACS at 70/160 mu m or 100/160 mu m, the HOBYS survey provides an unbiased and complete census of intermediate-to high-mass young stellar objects, some of which are not detected by Spitzer. Key core properties, such as bolometric luminosity and mass (as derived from spectral energy distributions), are used to constrain their evolutionary stages. We identify a handful of high-mass prestellar cores and show that their lifetimes could be shorter in the Rosette molecular complex than in nearby low-mass star-forming regions. We also quantify the impact of expanding H II regions on the star formation process acting in both Rosette and RCW 120.
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| 40. |
- Neufeld, D. A., et al.
(författare)
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The Widespread Occurrence of Water Vapor in the Circumstellar Envelopes of Carbon-Rich Asymptotic Giant Branch Stars: First Results From a Survey With Herschel/HIFI
- 2011
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 727:2
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Tidskriftsartikel (refereegranskat)abstract
- We report the preliminary results of a survey for water vapor in a sample of eight C stars with large mid-IR continuum fluxes: V384 Per, CIT 6, V Hya, Y CVn, IRAS 15194-5115, V Cyg, S Cep, and IRC+40540. This survey, performed using the HIFI instrument on board the Herschel Space Observatory, entailed observations of the lowest transitions of both ortho-and para-water: the 556.936 GHz 1(10)-1(01) and 1113.343 GHz 1(11)-0(00) transitions, respectively. Water vapor was unequivocally detected in all eight of the target stars. Prior to this survey, IRC+10216 was the only carbon-rich asymptotic giant branch (AGB) star from which thermal water emissions had been discovered, in that case with the use of the Submillimeter Wave Astronomy Satellite (SWAS). Our results indicate that IRC+10216 is not unusual, except insofar as its proximity to Earth leads to a large line flux that was detectable with SWAS. The water spectral line widths are typically similar to those of CO rotational lines, arguing against the vaporization of a Kuiper Belt analog being the general explanation for water vapor in carbon-rich AGB stars. There is no apparent correlation between the ratio of the integrated water line fluxes to the 6.3 mu m continuum flux-a ratio which measures the water outflow rate-and the total mass-loss rate for the stars in our sample.
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