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- ID:
- ivo://CDS.VizieR/J/A+AS/106/275
- Title:
- Theoretical isochrones
- Short Name:
- J/A+AS/106/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present large grids of theoretical isochrones for the initial chemical compositions [Z=0.0004, Y=0.23], [Z=0.004, Y=0.24], [Z=0.008, Y=0.25], [Z=0.02, Y=0.28], and [Z= 0.05, Y=0.352] and ages in the range 4Myr to 16Gyr. These isochrones are derived from stellar models computed with the most recent radiative opacities by Iglesias et al. (1992). In addition to this we present another set with chemical composition [Z=0.001, Y=0.23] based on models calculated with the radiative opacities by Huebner et al. (1977). All the stellar models are followed from the zero age main sequence (ZAMS) to the central carbon ignition for massive stars or to the beginning of the thermally pulsing regime of the asymptotic giant branch phase (TP-AGB) for low and intermediate mass stars. For each isochrone, we give the current mass, effective temperatures, bolometric and visual magnitudes, (U-B), (B-V), (V-R), (V-I), (V-J), (V-H), and (V-K) colors, and the luminosity function for the case of the Salpeter law. In addition to this, integrated magnitudes and colors at several characteristic points are also presented together with the mass of the remnant star when appropriate. The main characteristic that makes this set of isochrones very valuable is based on their extension in mass and chemical composition, besides the calculation of late stages of evolution, beyond the red giant tip till the white dwarf stage after the planetary nebula phase.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A116
- Title:
- Tucana dSph CMD and star formation history
- Short Name:
- J/A+A/630/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve the ancient star formation rates on a finer temporal scale than previously possible. We show that Tucana experienced three major phases of star formation, two very close together at ancient times and the last one ending between 6 and 8 Gyr ago. We show that the three discrete clumps of stars on the horizontal branch are linked to the distinct episodes of star formation in Tucana. The spatial distribution of the clumps reveals that each generation of stars presents a higher concentration than the previous one. The simultaneous modelling of the horizontal branch and the main sequence turn-off also allows us to measure the amount of mass lost by red giant branch stars in Tucana with unprecedented precision, confirming dwarf spheroidals to be excellent laboratories to study the advanced evolution of low-mass stars.
- ID:
- ivo://CDS.VizieR/II/37
- Title:
- UBV HR Diagrams of Globular Clusters
- Short Name:
- II/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBV observations of over 37,000 stars have been compiled from the literature to yield 165 color-magnitude diagrams. There is a list of bibliographic references for each cluster diagram.
- ID:
- ivo://CDS.VizieR/J/MNRAS/310/982
- Title:
- UBVI CCD Photometry of M11 - II.
- Short Name:
- J/MNRAS/310/982
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This directory contains Johnson-Cousins UBVI photometric data for M11 (NGC 6705) and a neighboring field (around PN G027.4-03.5). The photometric data for M11 are tightly matched to the SAAO E-region standard system (Menzies et al. SAAO Circ., 1989SAAOC..13....1M; Menzies et al., 1991MNRAS.248..642M; Kilkenny et al., 1998MNRAS.294...93K). For the PN G027.4-03.5 region, the standard system of Landolt (1992, Cat. <II/183>) was used and small systematic difference in photometry between the two tables may be present, in particular in (U-B). Table 2 contains UBVI data for 14,179 stars brighter than V=17mag in M11 (about 40arcmin x 40arcmin region). The star numbers and proper motion memberships by McNamara et al. (1977A&AS...27..117M) and Su et al. (1998, Cat. <J/A+AS/128/255>) are also identified and included. Table 3 contains UBVI data for 3,676 stars around PN G027.4-03.5.
- ID:
- ivo://CDS.VizieR/J/A+A/619/L8
- Title:
- Ultra-cool dwarfs candidates in Gaia DR2
- Short Name:
- J/A+A/619/L8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources. The resulting Hertzsprung-Russel diagram reveals fine structures throughout the mass range. This paper aims to investigate the content of Gaia DR2 at the low-mass end and to characterize ultra-cool and brown dwarfs. We first retrieved the sample of spectroscopically confirmed ultra-cool and brown dwarfs in Gaia DR2.We used their locus in the precise Hertzsprung-Russel diagram to select new candidates and to investigate their properties. The number of spectroscopically confirmed objects recovered in Gaia DR2 corresponds to 61% and 74% of the expected number of objects with an estimated Gaia magnitude G_est_<=21.5 and 20.3, respectively. This fills much of the gap to Gaia DR1. Furthermore, Gaia DR2 contains ~13000>=M7 and 631 new L candidates. A tentative classification suggests that a few hundred of them are young or subdwarf candidates. Their distance distribution shows that the solar neighborhood census is still incomplete. Conclusions. Gaia DR2 offers a great wealth of information on low-mass objects. It provides a homogeneous and precise catalog of candidates that is worthwhile to be further characterized with spectroscopic observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/24
- Title:
- VI photometry of sources in the halo of NGC253
- Short Name:
- J/ApJ/736/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained Magellan/IMACS and HST/ACS imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a~0.35+/-0.1. The total stellar mass of the halo is estimated to be M_halo ~2.5+/-1.5x10^9^M_{sun}_, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8+/-0.6, corresponding to a three-dimensional power law index of ~-4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictions for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.
- ID:
- ivo://CDS.VizieR/J/A+AS/112/291
- Title:
- VRI photometry of wide double stars
- Short Name:
- J/A+AS/112/291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are presenting VRI photometry of 93 wide visual double stars having late B- or A- type primaries, taken from the Annex of Double and Multiple Stars of the HIPPARCOS Input Catalogue. Spectral types have been estimated for most of the primaries and for the majority of the secondaries. 40% of them probably have common origin components, for which we calculated photometric parallaxes and some orbital values estimates.
- ID:
- ivo://CDS.VizieR/J/AJ/119/1748
- Title:
- WFPC 2 imaging of young LMC clusters
- Short Name:
- J/AJ/119/1748
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out Wide Field Planetary Camera 2 (WFPC2) F160BW, F555W, and F656N imaging of four young populous clusters: NGC 330, in the Small Magellanic Cloud, and NGC 1818, 2004, and 2100, in the Large Magellanic Cloud. We report photometric results for these four clusters, including identification using photometric colors of the cluster Be star population. We present theoretical WFPC2 and broadband colors and bolometric corrections for LMC and SMC metallicities. The use of the far-UV F160BW filter enables accurate determination of the effective temperatures for stars in the vicinity of the main-sequence turnoff and on the unevolved main sequence.
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