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11. Gamma Vel cluster membership and IMF
ID:
ivo://CDS.VizieR/J/A+A/589/A70
Title:
Gamma Vel cluster membership and IMF
Short Name:
J/A+A/589/A70
Date:
21 Oct 2021
Publisher:
CDS
Description:
Understanding the properties of young open clusters, such as the Initial Mass Function (IMF), star formation history and dynamic evolution, is crucial to obtain reliable theoretical predictions of the mechanisms involved in the star formation process. We want to obtain a list, as complete as possible, of confirmed members of the young open cluster Gamma Velorum, with the aim of deriving general cluster properties such as the IMF. We used all available spectroscopic membership indicators within the Gaia-ESO public archive together with literature photometry and X-ray data and, for each method, we derived the most complete list of candidate cluster members. Then, we considered photometry, gravity and radial velocities as necessary conditions to select a subsample of candidates whose membership was confirmed by using the lithium and H{alpha} lines and X-rays as youth indicators. We found 242 confirmed and 4 possible cluster members for which we derived masses using very recent stellar evolutionary models. The cluster IMF in the mass range investigated in this study shows a slope of {alpha}=2.6+/-0.5 for 0.5<M/M_{sun}<1.3 and {alpha}=1.1+/-0.4 for 0.16<M/M_{sun}_<0.5 and is consistent with a standard IMF. The similarity of the IMF of the young population around gamma^2^ Vel to that in other star forming regions and the field suggests it may have formed through very similar processes.
12. Geneva stellar evolution tracks and isochrones
ID:
ivo://CDS.VizieR/VI/102
Title:
Geneva stellar evolution tracks and isochrones
Short Name:
VI/102
Date:
21 Oct 2021
Publisher:
CDS
Description:
This database was created from an updated version of the empirically and semi-empirically calibrated BaSeL library of synthetic stellar spectra of Lejeune et al. (1997, Cat. <J/A+AS/125/229>, 1998, Cat. <J/A+AS/130/65>) and Westera et al. (1999, ASP Conference Series 192, 203-206) to calculate synthetic photometry in the (UBV)_J_(RI)_C_ JHKLL'M, HST-WFPC2, Geneva, and Washington systems for the entire set of non-rotating Geneva stellar evolution models covering masses from 0.4-0.8 to 120-150M_{sun}_ and metallicities Z=0.0004 (1/50Z_{sun}_) to 0.1 (5Z_{sun}_). The results are provided in a database which includes all individual stellar tracks and the corresponding isochrones covering ages from 10^3^yr to 16-20Gyr in time steps of {Delta}logt=0.05dex. The database also includes a new grid of stellar tracks of very metal-poor stars (Z=0.0004) from 0.8-150M_{sun}_ calculated with the Geneva stellar evolution code. The complete stellar grids are tabulated in the files table1.dat (summary), evol.dat (evolutionary models), and in the files ubv.dat, hst.dat, gen.dat and cmt.dat (synthetic colors in the different photometric systems). These grids are also available as mod* files in subdirectories evol, ubv, hst, gen and cmt. The isochrones for the different photometric systems are summarized in the file table2.dat; the parameters of the isochrones are tabulated in the file iso.dat, the detailed isochrones being available as files iso* in the subdirectories ubv, hst, gen and cmt.
13. Grids of stellar models III.
ID:
ivo://CDS.VizieR/J/A+AS/101/415
Title:
Grids of stellar models III.
Short Name:
J/A+AS/101/415
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stellar evolutionary models with mass loss and moderate overshooting at metallicity Z = 0.004 in the 0.80 to 120 M{sun} range are presented. They complete the set of grids computed with the same up-input physics for Z=0.020 and 0.001 by Schaller et al. (1992, Cat. J/A+AS/96/269), for Z=0.008 by Schaerer et al. (1992A&A...263..129S, Cat. J/A+AS/98/523) and for Z=0.040 by Schaerer et al. (1993, Cat. J/A+AS/102/339).
14. Grids of stellar models IV
ID:
ivo://CDS.VizieR/J/A+AS/102/339
Title:
Grids of stellar models IV
Short Name:
J/A+AS/102/339
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present grid of evolutionary sequences at metallicity Z=0.040, completes the set of grids computed for Z=0.020 and 0.001 by Schaller et al. (1992, Cat. J/A+AS/96/269), Z=0.008 by Schaerer et al. (1992, Cat. J/A+AS/98/523) and Z=0.004 by Charbonnel et al. (1993, Cat. J/A+AS/101/415). The models with mass loss and moderate core overshooting have been computed for 0.8 to 120 M{sun} using up-to-date input physics and the new radiative opacities from Iglesias et al. (1992ApJ...397..717I) and Kurucz (1991).
15. Grids of stellar models V.
ID:
ivo://CDS.VizieR/J/A+AS/103/97
Title:
Grids of stellar models V.
Short Name:
J/A+AS/103/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
Most outputs of massive star evolution critically depend on the mass loss rates. In order to broaden the comparison basis and to illustrate the effects of different mass loss rates, we have computed new sets of models, with initial masses between 12 and 120 M{sun}, and metallicities, Z, between 0.001 and 0.040, with a mass loss rate increased by a factor of two during the phases when the stellar winds are believed to be essentially driven by the radiation pressure. A moderate core-overshooting and the new radiative opacities from Iglesias et al. (1992ApJ...397..717I) and Kurucz (1991) were taken into account. These models complete the homogeneous and extended theoretical database formed by the previous grids of this series, computed by Schaller et al. (1992, Cat. J/A+AS/96/269) for Z=0.020 and Z=0.001, by Schaerer et al. (1992, Cat. J/A+AS/98/523; 1993, Cat. J/A+AS/102/339) for Z=0.008 and Z=0.040 and by Charbonnel et al. (1993, Cat. J/A+AS/101/415) for Z=0.004. This paper closes this series. Of particular interest is the predicted behaviour of metal rich stars such as may be found in the inner regions of our Galaxy. New evolutionary connexions are found, in particular we show that the most massive and metal rich stars may spend a relatively long time as He and N enriched stars and may even end their evolution as white dwarfs.
16. Grids of stellar models. VII.
ID:
ivo://CDS.VizieR/J/A+AS/128/471
Title:
Grids of stellar models. VII.
Short Name:
J/A+AS/128/471
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new grid of stellar models from 0.8 to 60M_{sun}_ at Z=0.10, with mass loss and moderate overshooting, from the zero age main sequence to either the helium flash (low mass stars), the early AGB phase (intermediate-mass stars or the end of carbon burning (massive stars). The calculations are done with opacities provided by Iglesias & Rogers (1993ApJ...412..752I), completed by those of Alexander & Ferguson (1994ApJ...437..879A) at low temperatures. This grid is a homogeneous extension to very high metallicity of the previous grids published by the Geneva group. It is useful for the study of galactic bulges, elliptical galaxies and eventually quasars. Calculations of stars more massive than 60M_{sun}_ are not presented as these objects lose almost their entire mass during their main sequence phase, and are likely to end their life as white dwarfs.
17. Grids of stellar models. VIII.
ID:
ivo://CDS.VizieR/J/A+AS/135/405
Title:
Grids of stellar models. VIII.
Short Name:
J/A+AS/135/405
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present stellar evolutionary models covering the mass range from 0.4 to 1M_{sun}_ calculated for metallicities Z=0.020 and 0.001 with the MHD equation of state (Hummer & Mihalas, 1988ApJ...331..794H, Mihalas et al., 1988ApJ...331..815M, Daeppen et al., 1988ApJ...332..261D). A parallel calculation using the OPAL (Rogers et al., 1996ApJ...456..902R) equation of state has been made to demonstrate the adequacy of the MHD equation of state in the range of 1.0 to 0.8M_{sun}_ (the lower end of the OPAL tables). Below, down to 0.4M_{sun}_, we have justified the use of the MHD equation of state by theoretical arguments and the findings of Chabrier & Baraffe (1997A&A...327.1039C). We use the radiative opacities by Iglesias & Rogers (1996ApJ...464..943I), completed with the atomic and molecular opacities by Alexander & Fergusson (1994ApJ...437..879A). We follow the evolution from the Hayashi fully convective configuration up to the redgiant tip for the most massive stars, and up to an age of 20Gyr for the less massive ones. We compare our solar-metallicity models with recent models computed by other groups and with observations.
18. HST color-magnitude diagrams of the LMC
ID:
ivo://CDS.VizieR/J/AJ/117/2244
Title:
HST color-magnitude diagrams of the LMC
Short Name:
J/AJ/117/2244
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results on the analysis of background field stars found in Hubble Space Telescope Wide Field Planetary Camera 2 observations of six of the old globular clusters of the Large Magellanic Cloud. Treated as contaminants by the globular cluster analysts, we produce (V-I, V) color-magnitude diagrams (CMDs) of the field stars and use them to explore the LMC's star formation history. The photometry approaches V {~} 26, well below the turnoff of an ancient ({~} 14 Gyr) LMC population of stars. The field star CMDs are generally characterized by an upper main sequence broadened by stellar evolution, an old red giant branch, a prominent red clump, and an unevolved lower main sequence. The CMDs also contain a few visual differences, the most obvious of which is the smeared appearance of the NGC 1916 field caused by heavy differential reddening. More subtly, the base of the subgiant branch near the old turnoff appears extended in V, and the red giant branch appears broad in V-I in four of the fields but not in the NGC 1754 field.
19. HST observations of old clusters in the LMC
ID:
ivo://CDS.VizieR/J/ApJ/527/199
Title:
HST observations of old clusters in the LMC
Short Name:
J/ApJ/527/199
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present V, V-I color-magnitude diagrams (CMDs) for three old star clusters in the Large Magellanic Cloud (LMC): NGC 1466, NGC 2257, and Hodge 11. Our data extend {~}3 mag below the main-sequence turnoff, allowing us to determine accurate relative ages and the blue straggler frequencies. Based on a differential comparison of the CMDs, any age difference between the three LMC clusters is less than 1.5 Gyr. Comparing their CMDs to those of M92 and M3, the LMC clusters, unless their published metallicities are significantly in error, are the same age as the old Galactic globulars. The similar ages to Galactic globulars are shown to be consistent with hierarchical clustering models of galaxy formation. The blue straggler frequencies are also similar to those of Galactic globular clusters. We derive a true distance modulus to the LMC of (m - M)_0_ = 18.46 {+/-} 0.09 [assuming (m - M)_0_ = 14.61 for M92] using these three LMC clusters.
20. JK Photometry of globular clusters M15 & M56
ID:
ivo://CDS.VizieR/J/AJ/119/2274
Title:
JK Photometry of globular clusters M15 & M56
Short Name:
J/AJ/119/2274
Date:
21 Oct 2021
Publisher:
CDS
Description:
Infrared JKs-band photometry of the Galactic globular clusters M15 and, for the first time, M56 is presented. We estimate the reddening [E(B-V) = 0.18 {=/-} 0.08 mag] and distance modulus [(m - M)V = 15.43 {+/-} 0.30 mag] toward the poorly studied globular cluster M56. We combine our data with observations of other clusters from the literature (12 in total) to extend the [Fe/H] versus red giant branch (RGB) slope relation toward metal-poor clusters.

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