- ID:
- ivo://CDS.VizieR/J/ApJ/887/91
- Title:
- Equivalent widths of giants in the GC NGC3201
- Short Name:
- J/ApJ/887/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Space Telescope (HST) UV Legacy Survey of Galactic Globular Clusters (GCs) has investigated multiple stellar populations by means of the "chromosome map" (ChM) diagnostic tool that maximizes the separation between stars with different chemical compositions. One of the most challenging features revealed by ChM analysis is the apparent inhomogeneity among stars belonging to the first population, a phenomenon largely attributed to He variations. However, this explanation is not supported by uniformity in the p-capture elements of these stars. The HST survey has revealed that the GC NGC 3201 shows exceptionally wide coverage in the {Delta}_F275W,F814W_ parameter of the ChM. We present a chemical abundance analysis of 24 elements in 18 giants belonging to the first population of this GC and having a wide range in {Delta}_F275W,F814W_. As far as the p-capture elements are concerned, the chemical abundances are typical of first-generation (1G) stars, as expected from the location of our targets in the ChM. Based on radial velocities and chemical abundance arguments, we find that the three stars with the lowest {Delta}_F275W,F814W_ values are binary candidates. This suggests that at least those stars could be explained with binarity. These results are consistent with evidence inferred from multiband photometry that evolved blue stragglers (BSs) populate the bluest part of the 1G sequence in the ChM. The remaining 15 spectroscopic targets show a small range in the overall metallicity by ~0.10dex, with stars at higher {Delta}_F275W,F814W_ values having higher absolute abundances. We suggest that a small variation in metals and binarity governs the color spread of the 1G in the ChM and that evolved BSs contribute to the bluest tail of the 1G sequence.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/500/1027
- Title:
- EROS CMD towards 4 Galactic spiral arms fields
- Short Name:
- J/A+A/500/1027
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The EROS-2 project has been designed to search for microlensing events towards any dense stellar field. The densest parts of the Galactic spiral arms have been monitored to maximize the microlensing signal expected from the stars of the Galactic disk and bulge. 12.9 million stars have been monitored during 7 seasons towards 4 directions in the Galactic plane, away from the Galactic center.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A60
- Title:
- EROS-2 Long Period Variables in LMC
- Short Name:
- J/A+A/536/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The EROS-2 survey has produced a database of millions of time series from stars monitored for more than six years, allowing us to classify some of their sources into different variable star types. Among the so-called, long period variables (LPVs), which are known to follow particular sequences in the period-luminosity diagram, we find long secondary period variables whose variability origin remains a matter of debate. We analyze data for the 856864 variable stars that have been discovered in the Large Magellanic Cloud (LMC) that are present in the EROS-2 database, to detect, classify, and characterize LPVs.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/68
- Title:
- 2016 eruption LC of the recurrent nova M31N 2008-12a
- Short Name:
- J/ApJ/857/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since its discovery in 2008, the Andromeda galaxy nova M31N 2008-12a has been observed in eruption every single year. This unprecedented frequency indicates an extreme object, with a massive white dwarf and a high accretion rate, which is the most promising candidate for the single-degenerate progenitor of a Type Ia supernova known to date. The previous three eruptions of M31N 2008-12a have displayed remarkably homogeneous multiwavelength properties: (i) from a faint peak, the optical light curve declined rapidly by two magnitudes in less than two days, (ii) early spectra showed initial high velocities that slowed down significantly within days and displayed clear He/N lines throughout, and (iii) the supersoft X-ray source (SSS) phase of the nova began extremely early, six days after eruption, and only lasted for about two weeks. In contrast, the peculiar 2016 eruption was clearly different. Here we report (i) the considerable delay in the 2016 eruption date, (ii) the significantly shorter SSS phase, and (iii) the brighter optical peak magnitude (with a hitherto unobserved cusp shape). Early theoretical models suggest that these three different effects can be consistently understood as caused by a lower quiescence mass accretion rate. The corresponding higher ignition mass caused a brighter peak in the free-free emission model. The less massive accretion disk experienced greater disruption, consequently delaying the re-establishment of effective accretion. Without the early refueling, the SSS phase was shortened. Observing the next few eruptions will determine whether the properties of the 2016 outburst make it a genuine outlier in the evolution of M31N 2008-12a.
575. ER Vulpeculae
- ID:
- ivo://CDS.VizieR/J/A+A/291/110
- Title:
- ER Vulpeculae
- Short Name:
- J/A+A/291/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/384/81
- Title:
- ESO Imaging Survey. CDF-S point sources
- Short Name:
- J/A+A/384/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes the methodology currently being implemented in the EIS pipeline for analysing optical/infrared multi-colour data. The aim is to identify different classes of objects as well as possible undesirable features associated with the construction of colour catalogues. The tools developed are used for a preliminary analysis of the multi-colour point source catalogue constructed from the optical/infrared imaging data obtained for the Chandra Deep Field South (CDF-S). These data are publicly available, representing the first installment of the ongoing EIS Deep Public Survey.
- ID:
- ivo://CDS.VizieR/J/A+AS/137/75
- Title:
- ESO Imaging Survey. IV.
- Short Name:
- J/A+AS/137/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents preliminary lists of potentially interesting point-like sources extracted from multicolour data obtained for a 1.7 square degree region near the South Galactic Pole. The region has been covered by the ESO Imaging Survey (EIS) in B, V and I and offers a unique combination of area and depth. These lists, containing a total of 330 objects nearly all brighter than I~21.5, over 1. 27 square degrees (after removing some bad regions), are by-products of the process of verification and quality control of the object catalogs being produced. Among the colour selected targets are candidate very low mass stars/brown dwarfs (54), white-dwarfs (32), and quasars (244). In addition, a probable fast moving asteroid was identified. The objects presented here are natural candidates for follow-up spectroscopic observations and illustrate the usefulness of the EIS data for a broad range of science and for providing possible samples for the first year of the VLT.
- ID:
- ivo://CDS.VizieR/J/AJ/118/2071
- Title:
- ESO 565-11 UBVI(c) photometry
- Short Name:
- J/AJ/118/2071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiband Wide Field Planetary Camera 2 images of the central regions of ESO 565-11, a peculiar southern barred galaxy recently shown to have the largest known example of a circumnuclear starburst ring. We also present ground-based near-infrared H-band imaging and photometry of the galaxy. The results provide an interesting picture of the star-forming ring and its environment.
- ID:
- ivo://CDS.VizieR/J/A+A/361/1023
- Title:
- Evolution models for {alpha}-enhanced stars
- Short Name:
- J/A+A/361/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present four large sets of evolutionary tracks for stars with initial chemical compositions [Y=0.250, Z=0.008], [Y=0.2773, Z=0.019], [Y=0.320, Z=0.040] and [Y=0.390, Z=0.070] and enhancement of {alpha} elements with respect to the solar pattern. The major improvement with respect to previous similar calculations is that we use consistent opacities - i.e. computed with the same chemical composition as adopted in the stellar models - over the whole relevant range of temperatures. For the same initial chemical compositions [Y, Z] and otherwise identical input physics we present also new evolutionary sequences with solar-scaled mixtures of abundances. Based on these stellar models we calculate the corresponding sets of isochrones both in the Johnson-Cousins UBVRIJHK and HST/WFPC2 photometric systems. Furthermore, we derive integrated magnitudes, colours and mass-to-light ratios for ideal single stellar populations with total mass equal to 1M_{sun}_ Finally, the major changes in the tracks, isochrones, and integrated magnitudes and colours passing from solar-scaled to {alpha}-enhanced mixtures are briefly outlined. Retrieval of the complete data set is possible via the www page http://pleiadi.pd.astro.it .
- ID:
- ivo://CDS.VizieR/J/A+A/311/361
- Title:
- Evolution models of elliptical galaxies. II.
- Short Name:
- J/A+A/311/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present new chemo-spectro-photometric models of elliptical galaxies in which infall of primordial gas is allowed to occur. They aim to simulate the collapse of a galaxy made of two components, i.e. luminous material and dark matter. The mass of the dark component is assumed to be constant in time, whereas that of the luminous material is supposed to accrete at a suitable rate. They also include the effect of galactic winds powered by supernova explosions and stellar winds from massive, early-type stars. The models are constrained to match a number of properties of elliptical galaxies, i.e. the slope and mean colours of the colour-magnitude relation (CMR), V versus (V-K), the UV excess as measured by the colour (1550-V) together with the overall shape of the integrated spectral energy distribution (ISED) in the ultraviolet, the relation between the Mg_2_ index and (1550-V), the mass to blue luminosity ratio M/L_B_ as a function of the B luminosity, and finally the broad-band colours (U-B), (B-V), (V-I), (V-K), etc. The CMR is interpreted as a mass-metallicity sequence of old, nearly coeval objects, whose mean age is 15Gyr. Assuming the law of star formation to be proportional to M_g_^k^(t) with k=1, the rate of star formation as function of time starts small, grows to a maximum, and then declines thus easily avoiding the excess of metal-poor stars found by BCF with the closed-box scheme (the analog of the G-Dwarf Problem in the solar vicinity). Owing to their stellar content, infall models can easily reproduce all the basic data of the galaxies under examination. As far as the UV excess is concerned, the same sources proposed by BCF are found to hold also with the infall scheme. H-HB and AGB manque stars of high metallicity play the dominant role, and provide a robust explanation of the correlation between the (1550-V) colour and the luminosity, mass and metallicity of the galaxies. Furthermore, these models confirm the potential of the (1550-V) colour as an age indicator in cosmology as already suggested by BCF. In the rest frame of a massive and metal-rich elliptical galaxy, this colour suffers from one major variation: at the onset of the so-called H-HB and AGB-manque stars (age about 5.6Gyr). This transition occurs at reasonably small red-shifts and therefore could be detected with the present-day instrumentation.
