- ID:
- ivo://CDS.VizieR/J/A+A/597/A30
- Title:
- Seismology and spectroscopy of CoRoGEE red giants
- Short Name:
- J/A+A/597/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the CoRoGEE dataset -- obtained from CoRoT lightcurves for 606 red giant stars in two fields of the Galactic disc which have been co-observed for an ancillary project of the Apache Point Observatory Galactic Evolution Experiment (APOGEE). The CoRoGEE stars cover a large radial range of the Milky Way's disc (5kpc<RGal<14kpc) and thus provide a valuable dataset for Galactic Archaeology studies. We have used the Bayesian parameter estimation code PARAM to calculate distances, extinctions, masses, and ages for these stars in a homogeneous analysis, resulting in relative statistical uncertainties of 2% in distance, 4% in radius, ~9% in mass and ~25% in age. We also assess systematic age uncertainties due to different input physics and mass loss.
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Search Results
1492. Semiempirical gf Values
- ID:
- ivo://CDS.VizieR/VI/10
- Title:
- Semiempirical gf Values
- Short Name:
- VI/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table of gf values for 265,587 atomic lines is selected from the line data used to calculate line-blanketed model atmospheres (Kurucz et al. 1974). The data are especially useful for line identification and spectral synthesis in solar and stellar spectra. Except for 10,100 lines taken from the literature, the gf values have been calculated semiempirically by using scaled Thomas-Fermi-Dirac radial wavefunctions and eigenvectors found through least-squares fits to observed energy levels. Included in the calculation were the first five or six stages of ionization for sequences up through nickel. Published gf values have been included for elements heavier than nickel. The tabulation is restricted to lines with wavelengths less than 10um.
- ID:
- ivo://CDS.VizieR/J/A+A/517/A21
- Title:
- Sensitivity analysis list of chemical reactions
- Short Name:
- J/A+A/517/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Because of new telescopes that will dramatically improve our knowledge of the interstellar medium, chemical models will have to be used to simulate the chemistry of many regions with diverse properties. To make these models more robust, it is important to understand their sensitivity to a variety of parameters. In this article, we report a study of the sensitivity of a chemical model of a cold dense core, with homogeneous and time-independent physical conditions, to variations in the following parameters: initial chemical inventory, gas temperature and density, cosmic-ray ionization rate, chemical reaction rate coefficients, and elemental abundances.
- ID:
- ivo://CDS.VizieR/J/ApJ/882/9
- Title:
- SFR & gas-phase metallicity in MaNGA gal.
- Short Name:
- J/ApJ/882/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of gas accretion in galaxy evolution is still a matter of debate. The presence of inflows of metal-poor gas that trigger star formation bursts of low metallicity has been proposed as an explanation for the local anticorrelation between star formation rate (SFR) and gas-phase metallicity (Z_g_) found in the literature. In the present study, we show how the anticorrelation is also present as part of a diversified range of behaviors for a sample of more than 700 nearby spiral galaxies from the SDSS-IV MaNGA survey. We have characterized the local relation between SFR and Z_g_ after subtracting the azimuthally averaged radial profiles of both quantities. Of the analyzed galaxies, 60% display an SFR-Z_g_ anticorrelation, with the remaining 40% showing no correlation (19%) or positive correlation (21%). Applying a random forest machine-learning algorithm, we find that the slope of the correlation is mainly determined by the average gas-phase metallicity of the galaxy. Galaxy mass, g-r colors, stellar age, and mass density seem to play a less significant role. This result is supported by the performed second-order polynomial regression analysis. Thus, the local SFR-Z_g_ slope varies with the average metallicity, with the more metal-poor galaxies presenting the lowest slopes (i.e., the strongest SFR-Z_g_ anticorrelations), and reversing the relation for more metal-rich systems. Our results suggest that external gas accretion fuels star formation in metal-poor galaxies, whereas in metal-rich systems, the gas comes from previous star formation episodes.
1495. SFR of distant galaxies
- ID:
- ivo://CDS.VizieR/J/A+A/430/115
- Title:
- SFR of distant galaxies
- Short Name:
- J/A+A/430/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of distant galaxies have shown that ellipticals and large spirals (Schade et al., 1999ApJ...525...31S; Lilly et al., 1998ApJ...500...75L) were already in place 8Gyr ago, leading to a very modest recent star formation (Brinchmann & Ellis, 2000ApJ...536L..77B) in intermediate mass galaxies (3-30*10^10^M_{sun}_). This is challenged by a recent analysis (Heavens et al., 2004Natur.428..625H) of the fossil record of the stellar populations of ~105 nearby galaxies, which shows that intermediate mass galaxies formed or assembled the bulk of their stars 4 to 8Gyr ago. Here we present direct observational evidence supporting this findings from a long term, multi-wavelength study of 195 z>0.4 intermediate mass galaxies, mostly selected from the Canada France Redshift Survey (CFRS, Cat. <VII/225>).
- ID:
- ivo://CDS.VizieR/J/A+A/641/A135
- Title:
- Sgr dSph CEMP-r/s star abundance analysis
- Short Name:
- J/A+A/641/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the discovery and chemical abundance analysis of the first CEMP-r/s star detected in the Sagittarius dwarf spheroidal galaxy (Sgr dSph) by means of UVES high-resolution spectra. The star, found in the outskirts of Sgr dSph, along the major axis of the main body, is a moderately metal-poor giant (Teff=4753K, logg=1.75, [Fe/H]=-1.55) with [C/Fe]=1.13, placing it in the so-called "high-carbon band", and strong s-process and r-process enrichment ([Ba/Fe]=1.4, [Eu/Fe]=1.01). Abundances of 29 elements from C to Dy were obtained. The chemical pattern appears to be best fitted by a scenario where an r-process pollution event pre-enriched the material out of which the star was born as secondary in a binary system whose primary evolved through the AGB phase, providing C- and s-process enrichment.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A46
- Title:
- Sgr dSph nucleus stars chemical abundances
- Short Name:
- J/A+A/605/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Iron, Magnesium, Calcium, and Titanium abundances for 235 stars in the central region of the Sagittarius dwarf spheroidal galaxy (within 9.0'~=70pc from the center) from medium-resolution Keck/DEIMOS spectra. All the considered stars belong to the massive globular cluster M 54 or to the central nucleus of the galaxy (Sgr,N). In particular we provide abundances for 109 stars with [Fe/H]>=-1.0, more than doubling the available sample of spectroscopic metallicity and {alpha}-elements abundance estimates for Sgr dSph stars in this metallicity regime. We find for the first time a metallicity gradient in the Sgr,N population, whose peak iron abundance goes from [Fe/H]=-0.38 for R<=2.5' to [Fe/H]=-0.57 for 5.0<R<=9.0 arcmin. On the other hand the trends of [Mg/Fe], [Ca/Fe], and [Ti/Fe] with [Fe/H] are the same over the entire region explored by our study. We reproduce the observed chemical patterns of the Sagittarius dwarf spheroidal as a whole with a chemical evolution model implying a high mass progenitor (M_DM_=6x10^10^M_{sun}_) and a significant event of mass-stripping occurred a few Gyr ago, presumably starting at the first peri-Galactic passage after infall.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/154
- Title:
- Sgr stream K- & M-giants and BHB stars
- Short Name:
- J/ApJ/886/154
- Date:
- 07 Dec 2021 13:01:04
- Publisher:
- CDS
- Description:
- We characterize the kinematic and chemical properties of ~3000 Sagittarius (Sgr) stream stars, including K-giants, M-giants, and blue horizontal branch stars (BHBs), selected from SEGUE-2, Large Sky Area Multi-Object Fibre Spectroscopic Telescope, and Sloan Digital Sky Survey separately in Integrals-of-Motion space. The orbit of the Sgr stream is quite clear from the velocity vector in the X-Z plane. Stars traced by K-giants and M-giants show that the apogalacticon of the trailing steam is ~100kpc. The metallicity distributions of Sgr K-giants, M-giants, and BHBs indicate that the M-giants are on average the most metal-rich population, followed by K-giants and BHBs. All of the K-giants, M-giants, and BHBs indicate that the trailing arm is on average more metal-rich than the leading arm, and the K-giants show that the Sgr debris is the most metal-poor part. The {alpha}-abundance of Sgr stars exhibits a similar trend with the Galactic halo stars at lower metallicity ([Fe/H]<~-1.0dex), and then evolve down to lower [{alpha}/Fe] than disk stars at higher metallicity, which is close to the evolution pattern of the {alpha}-element of Milky Way dwarf galaxies. We find that VY and metallicity of K-giants have gradients along the direction of the line of sight from the Galactic center in the X-Z plane, and the K-giants show that VY increases with metallicity at [Fe/H]>~-1.5dex. After dividing the Sgr stream into bright and faint streams according to their locations in equatorial coordinates, the K-giants and BHBs show that the bright and faint streams present different VY and metallicities, the bright stream is on average higher in VY and metallicity than the faint stream.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/35
- Title:
- SHELS: complete galaxy redshift survey for R<=20.6
- Short Name:
- J/ApJS/213/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R=20.6. Here we describe the redshift survey of the F2 field (RA_J2000_=09h19m32.4s and DE_J2000_=+30{deg}00'00"). The survey includes 16294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4deg^2^ F2 field is 95% complete to R=20.6, currently the densest survey to this magnitude limit. The median survey redshift is z=0.3; the survey provides a view of structure in the range 0.1<~z<~0.6. An animation displays the large-scale structure in the survey region. We provide a redshift, spectral index D_n_4000, and stellar mass for each galaxy in the survey. We also provide a metallicity for each galaxy in the range 0.2<z<0.38. To demonstrate potential applications of the survey, we examine the behavior of the index D_n_4000 as a function of galaxy luminosity, stellar mass, and redshift. The known evolutionary and stellar mass dependent properties of the galaxy population are cleanly evident in the data. We also show that the mass-metallicity relation previously determined from these data is robust to the analysis approach.
- ID:
- ivo://CDS.VizieR/J/AJ/156/277
- Title:
- Sixty validated planets from K2 campaigns 5-8
- Short Name:
- J/AJ/156/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a uniform analysis of 155 candidates from the second year of NASA's K2 mission (Campaigns 5-8), yielding 60 statistically validated planets spanning a range of properties with median values of R_p_=2.5 R_{Earth}_, P=7.1 days, T_eq_=811 K, and J=11.3 mag. The sample includes 24 planets in 11 multiplanetary systems, as well as 18 false positives and 77 remaining planet candidates. Of particular interest are 18 planets smaller than 2 R_{Earth}_, five orbiting stars brighter than J=10 mag, and a system of four small planets orbiting the solar-type star EPIC 212157262. We compute planetary transit parameters and false-positive probabilities using a robust statistical framework and present a complete analysis incorporating the results of an intensive campaign of high-resolution imaging and spectroscopic observations. This work brings the K2 yield to over 360 planets, and by extrapolation, we expect that K2 will have discovered ~600 planets before the expected depletion of its onboard fuel in late 2018.
