- ID:
- ivo://CDS.VizieR/J/A+A/574/A129
- Title:
- The First CEMP star in the Sculptor dSph
- Short Name:
- J/A+A/574/A129
- Date:
- 04 Feb 2022 11:54:02
- Publisher:
- CDS
- Description:
- he origin of carbon-enhanced metal-poor (CEMP) stars and their possible connection with the chemical elements produced by the first stellar generation is still highly debated. In contrast to the Galactic halo, not many CEMP stars have been found in the dwarf spheroidal galaxies around the Milky Way. Here we present detailed abundances from ESO VLT/UVES high-resolution spectroscopy for ET0097, the first CEMP star found in the Sculptor dwarf spheroidal, which is one of the best studied dwarf galaxies in the Local Group. This star has [Fe/H]=-2.03+/-0.10, [C/Fe]=0.51+/-0.10 and [N/Fe]=1.18+/-0.20, which is the first nitrogen measurement in this galaxy. The traditional definition of CEMP stars is [C/Fe]>=0.70, but taking into account that this luminous red giant branch star has undergone mixing, it was intrinsically less nitrogen enhanced and more carbon-rich when it was formed, and so it falls under the definition of CEMP stars, as proposed by Aoki et al. (2007ApJ...655..492A, Cat. J/ApJ/655/492) to account for this effect.
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1702. The GALAH+ Survey DR3
- ID:
- ivo://CDS.VizieR/J/MNRAS/506/150
- Title:
- The GALAH+ Survey DR3
- Short Name:
- J/MNRAS/506/150
- Date:
- 12 Jan 2022 13:26:47
- Publisher:
- CDS
- Description:
- The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the MilkyWay.With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2 per cent of stars are within <2 kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope. This release (hereafter GALAH+ DR3) includes all observations from GALAH Phase 1 (bright, main, and faint survey, 70 per cent), K2-HERMES (17 per cent), TESS-HERMES (5 per cent), and a subset of ancillary observations (8 per cent) including the bulge and >75 stellar clusters. We derive stellar parameters Teff, logg, [Fe/H], vmic, vbroad, and vrad using our modified version of the spectrum synthesis code Spectroscopy Made Easy (SME) and 1D MARCS model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from Gaia DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65 per cent dwarfs, 34 per cent giants, and 1 per cent other/unclassified stars. Based on unflagged chemical composition and age, we find 62 per cent young low-alpha, 9 per cent young high-alpha, 27 per cent old high-alpha, and 2 per cent stars with [Fe/H]<=-1. Based on kinematics, 4 per cent are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after Gaia eDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.
- ID:
- ivo://CDS.VizieR/J/AJ/155/116
- Title:
- The globular cluster M14.II. Variable stars
- Short Name:
- J/AJ/155/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series BVI photometry for the Galactic globular cluster NGC 6402 (M14). The data consist of ~137 images per filter, obtained using the 0.9 and 1.0 m SMARTS telescopes at the Cerro Tololo Inter-American Observatory. The images were obtained during two observing runs in 2006-2007. The image-subtraction package ISIS, along with DAOPHOT II/ALLFRAME, was used to perform crowded-field photometry and search for variable stars. We identified 130 variables, eight of which are new discoveries. The variable star population is comprised of 56 ab-type RR Lyrae stars, 54 c-type RR Lyrae, 6 type II Cepheids, 1 W UMa star, 1 detached eclipsing binary, and 12 long-period variables. We provide Fourier decomposition parameters for the RR Lyrae, and discuss the physical parameters and photometric metallicity derived therefrom. The M14 distance modulus is also discussed, based on different approaches for the calibration of the absolute magnitudes of RR Lyrae stars. The possible presence of second-overtone RR Lyrae in M14 is critically addressed, with our results arguing against this possibility. By considering all of the RR Lyrae stars as members of the cluster, we derive <P_ab_>=0.589 days. This, together with the position of the RR Lyrae stars of both Bailey types in the period-amplitude diagram, suggests an Oosterhoff-intermediate classification for the cluster. Such an intermediate Oosterhoff type is much more commonly found in nearby extragalactic systems, and we critically discuss several other possible indications that may point to an extragalactic origin for this cluster.
1704. The Hypatia Catalog (
- ID:
- ivo://CDS.VizieR/J/AJ/148/54
- Title:
- The Hypatia Catalog (
- Short Name:
- J/AJ/148/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hypatia Catalog is a compilation of abundance measurements from 84 literature sources for FGK stars within 150pc of the Sun. The full, raw, un-reduced catalog contains +3000 stars and can be found with the online journal paper. Provided here is the reduced catalog where stars are excluded if 1) they are probable thick-disk stars per Bensby et al. (2003A&A...410..527B, Cat. J/A+A/410/527) and 2) the spread in the compiled measurements for a star in either [X/Fe] or [Fe/H] is larger than the respective error in cases where multiple groups measured the same element in the same star. When abundance determinations were well agreed upon by multiple sources (or when the spread was less than the respective error), the median value of those measurements is found in the machine readable table here. In addition, all abundances here were re-normalized to the Lodders et al. (2009, Landolt-Bornstein-Group VI Astronomy and Astrophysics Numerical Data and Functional Relationships in Science and Technology Volume 4B: Solar System, ed. J. E. Trumper (Berlin: Springer), 44) solar abundance scale. Please see the main paper for more details. To facilitate use of the Hypatia Catalog, the reduced abundance determinations have been provided in this machine-readable format. However, there are two caveats which must be addressed. To begin, Hypatia is a three-dimensional catalog and placing it in two-dimensions created limitations, specifically for [Fe/H]. As an example, if five literature sources measured abundances in a star, then there are five [Fe/H] values. However, if only two of those five measured [X/Fe] within the star, then only the median of the two corresponding [Fe/H] values were used to produce the [X/Fe] Figs. 5-30 in the paper. Rather than give unique [Fe/H] determinations for each element with only the corresponding [Fe/H] values, the median of *all* [Fe/H] measurements are given in the FeH column. Per the example, we used the median of all five [Fe/H] measurements. Since elements with spreads larger than respective error are not included, we found that using all of the well agreed upon [Fe/H] measurements to be a conservative choice. Second, Hypatia is an ever-growing database where new measurements will be incorporated as they are released. We have made some small but important updates to the machine readable table. These two caveats only slightly affected the abundance results as compared to the figures in the paper and did not alter the main results and discussion of the paper. Inclusions of more recent surveys and major changes to trends will be addressed in subsequent publications and will be made available online. It is our hope to put all of the abundance data in a flexible database format in the near future.
- ID:
- ivo://CDS.VizieR/J/AJ/156/286
- Title:
- The LEECH exoplanet imaging survey
- Short Name:
- J/AJ/156/286
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the largest L' (3.8 {mu}m) direct imaging survey for exoplanets to date, the Large Binocular Telescope Interferometer Exozodi Exoplanet Common Hunt (LEECH). We observed 98 stars with spectral types from B to M. Cool planets emit a larger share of their flux in L' compared to shorter wavelengths, affording LEECH an advantage in detecting low-mass, old, and cold-start giant planets. We emphasize proximity over youth in our target selection, probing physical separations smaller than other direct imaging surveys. For FGK stars, LEECH outperforms many previous studies, placing tighter constraints on the hot-start planet occurrence frequency interior to ~20 au. For less luminous, cold-start planets, LEECH provides the best constraints on giant-planet frequency interior to ~20 au around FGK stars. Direct imaging survey results depend sensitively on both the choice of evolutionary model (e.g., hot- or cold-start) and assumptions (explicit or implicit) about the shape of the underlying planet distribution, in particular its radial extent. Artificially low limits on the planet occurrence frequency can be derived when the shape of the planet distribution is assumed to extend to very large separations, well beyond typical protoplanetary dust-disk radii (~<50 au), and when hot-start models are used exclusively. We place a conservative upper limit on the planet occurrence frequency using cold-start models and planetary population distributions that do not extend beyond typical protoplanetary dust-disk radii. We find that ~<90% of FGK systems can host a 7-10 M_Jup_ planet from 5 to 50 au. This limit leaves open the possibility that planets in this range are common.
- ID:
- ivo://CDS.VizieR/J/ApJ/762/25
- Title:
- The most metal-poor stars in HES and SDSS. I.
- Short Name:
- J/ApJ/762/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 34 stars in the Hamburg/ESO Survey (HES) for metal-poor stars and the Sloan Digital Sky Survey (SDSS) that have [Fe/H]<~-3.0. Their median and minimum abundances are [Fe/H]=-3.1 and -4.1, respectively, while 10 stars have [Fe/H]<-3.5. High-resolution, high signal-to-noise spectroscopic data --equivalent widths and radial velocities-- are presented for these stars, together with an additional four objects previously reported or currently being investigated elsewhere. We have determined the atmospheric parameters, effective temperature (T_eff_), and surface gravity (logg), which are critical in the determination of the chemical abundances and the evolutionary status of these stars. Three techniques were used to derive these parameters. Spectrophotometric fits to model atmosphere fluxes were used to derive T_eff_, logg, and an estimate of E(B-V); H{alpha}, H{beta}, and H{gamma} profile fitting to model atmosphere results provided the second determination of T_eff_and logg; and finally, we used an empirical T_eff_-calibrated H{delta} index, for the third, independent T_eff_determination. The three values of T_eff_ are in good agreement, although the profile fitting may yield systematically cooler T_eff_values, by ~100K. This collective data set will be analyzed in future papers in the present series to utilize the most metal-poor stars as probes of conditions in the early universe.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/84
- Title:
- Theoretical framework for RR Lyrae. II. MIR data
- Short Name:
- J/ApJ/841/84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new theoretical period-luminosity-metallicity (PLZ) relations for RR Lyrae stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances (Z=0.0001-0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, {mu}0, and extinction, A_V_, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia's first data release. For M4, we find a distance modulus of {mu}0=11.257+/-0.035mag with A_V_=1.45+/-0.12mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ~0.02mag at mid-infrared wavelengths.
1708. The PASTEL catalogue
- ID:
- ivo://CDS.VizieR/B/pastel
- Title:
- The PASTEL catalogue
- Short Name:
- B/pastel
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PASTEL is a bibliographical catalogue compiling determinations of stellar atmospheric parameters. It provides (Teff, logg, [Fe/H]) determinations obtained from detailed analyses of high resolution, high signal to noise spectra, carried out with the help of model atmospheres. It also provides effective temperatures Teff from various methods. PASTEL is regularly updated. The catalogue supersedes the two previous versions of the [Fe/H] catalogue (Cayrel de Strobel et al., 1997 [Cat. III/200], 2001 [Cat. III/221]). PASTEL is regularly updated.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/77
- Title:
- The PHLEK survey: oxygen & helium abundances
- Short Name:
- J/ApJ/896/77
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present Keck NIRSPEC and Keck NIRES spectroscopy of sixteen metal-poor galaxies that have pre-existing optical observations. The near-infrared (NIR) spectroscopy specifically targets the HeI{lambda}10830{AA} emission line, due to its sensitivity to the physical conditions of the gas in HII regions. We use these NIR observations, combined with optical spectroscopy, to determine the helium abundance of sixteen galaxies across a metallicity range 12+log_10_(O/H)=7.13-8.00. This data set is combined with two other samples where metallicity and helium abundance measurements can be secured: star-forming galaxies selected from the Sloan Digital Sky Survey spectroscopic database, and existing low-metallicity systems in the literature. We calculate a linear fit to these measurements, accounting for intrinsic scatter, and report a new determination of the primordial helium number abundance, y_P_=0.0805_-0.0017_^+0.0017^, which corresponds to a primordial helium mass fraction Y_P_=0.2436_-0.0040_^+0.0039^. Using our determination of the primordial helium abundance in combination with the latest primordial deuterium measurement, (D/H)_P_x10^5^=2.527+/-0.030, we place a bound on the baryon density {Omega}_b_h^2^=0.0215_-0.0005_^+0.0005^ and the effective number of neutrino species N_eff_=2.85_-0.25_^+0.28^. These values are in 1.3{sigma} agreement with those deduced from the Planck satellite observations of the temperature fluctuations imprinted on the cosmic microwave background.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/1102
- Title:
- The planet-metallicity correlation.
- Short Name:
- J/ApJ/622/1102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have recently carried out spectral synthesis modeling to determine T_eff_, log(g), vsin(i), and [Fe/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K>30m/s and orbital periods shorter than 4yr.