- ID:
- ivo://CDS.VizieR/J/ApJS/230/28
- Title:
- The populations of Carina. II. Abundances
- Short Name:
- J/ApJS/230/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Chemical abundances are presented for 19 elements in a sample of 63 red giants in the Carina dwarf spheroidal galaxy (dSph), based on homogeneous 1D/LTE model atmosphere analyses of our own observations (32 stars) and data available in the literature (a further 31 independent stars). The (Fe) metallicity and [{alpha}/Fe] distribution functions have mean values and dispersions of -1.59 and 0.33dex ([Fe/H] range: -2.68 to -0.64) and 0.07 and 0.13dex ([{alpha}/Fe] range: -0.27 to 0.25), respectively. We confirm the finding of Venn+ (2012, J/ApJ/751/102) that a small percentage (some 10% in the present investigation) of the sample shows clear evidence for significant enrichment by Type Ia supernova (SN Ia) ejecta. Calcium, with the most accurately determined abundance of the {alpha}-elements, shows an asymmetric distribution toward smaller values of [Ca/Fe] at all [Fe/H], most significantly over -2.0<[Fe/H]<-1.0, suggestive of incomplete mixing of the ejecta of SNe Ia with the ambient medium of each of Carina's generations. Approximate color-magnitude diagram age estimates are presented for the sample, and together with our chemical abundances, compared with the results of our previous synthetic color-magnitude diagram analysis, which reported the details of Carina's four well-defined populations. We searched for the Na-O anticorrelation universally reported in the Galaxy's globular clusters and confirm that this phenomenon does not exist in Carina. We also found that one of the 32 stars in our sample has an extremely enhanced lithium abundance-A(Li)_NLTE_=+3.36, consistent with membership of the ~1% group of Li-rich stars in dSph described by Kirby+ (2012ApJ...752L..16K).
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/643/A146
- Title:
- The solar gravitational redshift
- Short Name:
- J/A+A/643/A146
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The General Theory of Relativity predicts the redshift of spectral lines in the solar photosphere, as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum of the Sun's reflected light on solar system bodies. The laser frequency comb (LFC) calibration system attached to the HARPS spectrograph offers the possibility to perform an accurate measurement of the solar gravitational redshift (GRS) by observing the Moon or other solar system bodies. We have analysed the line shift observed in Fe absorption lines from five high-quality HARPS-LFC spectra of the Moon. We select an initial sample of 326 photospheric Fe lines in the spectral range 476-585nm and measure their line positions and equivalent widths (EWs). Accurate line shifts are derived from the wavelength position of the core of the lines compared with the laboratory wavelengths of Fe lines. We also use a CO^5^BOLD 3D hydrodynamical model atmosphere of the Sun to compute 3D synthetic line profiles of a subsample of about 200 spectral Fe lines centred at their laboratory wavelengths. We fit the observed relatively weak spectral Fe lines (with EW<180m{AA}) with the 3D synthetic profiles. Convective motions in the solar photosphere do not affect the line cores of Fe lines stronger than about 150m{AA}. In our sample, only 15 FeI lines have EWs in the range 150<EW(m{AA})<550, providing a measurement of the solar GRS at 639+/-14m/s, consistent with the expected theoretical value on Earth of 633.1m/s. A final sample of about 98 weak Fe lines with EW<180m{AA} allows us to derive a mean global line shift of 638+/-6m/s in agreement with the theoretical solar GRS. These are the most accurate measurements of the solar GRS so far. Ultrastable spectrographs calibrated with the LFC over a larger spectral range, such as HARPS or ESPRESSO, together with a further improvement on the laboratory wavelengths, could provide a more robust measurement of the solar GRS and further tests for the 3D hydrodynamical models.
- ID:
- ivo://CDS.VizieR/J/AJ/156/49
- Title:
- The solar neighborhood. XLIII. New nearby stars
- Short Name:
- J/AJ/156/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a novel search of most of the southern sky for nearby red dwarfs having low proper motions, with specific emphasis on those with {mu}<0.18"/yr, the lower cutoff of Luyten's classic proper-motion catalog. We used a tightly constrained search of the SuperCOSMOS database and a suite of photometric distance relations for photographic BRI and 2MASS JHK_s_ magnitudes to estimate distances to more than 14 million red dwarf candidates. Here we discuss 29 stars in 26 systems estimated to be within 25 pc, all of which have {mu}<0.18"/yr, that we have investigated using milliarcsecond astrometry, VRI photometry, and low-resolution spectroscopy. In total, we present the first parallaxes of 20 star systems, 9 of which are within 25 pc. We have additionally identified 14 young M dwarfs, of which 3 are new members of the nearby young moving groups, and 72 new giants, including two new carbon stars. We also present the entire catalog of 1215 sources we have identified by this means.
- ID:
- ivo://CDS.VizieR/J/AJ/154/151
- Title:
- The solar neighborhood .XXXX. New young stars
- Short Name:
- J/AJ/154/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a step toward completing and characterizing the census of the solar neighborhood, we present astrometric, photometric, and spectroscopic observations of 32 systems observed with the Cerro Tololo Inter-American Observatory 0.9 m and 1.5 m telescopes. Astrometry from the 0.9 m indicates that among the 17 systems that had no previous published trigonometric parallaxes, 14 are within 25 pc. In the full sample, nine systems have proper motions larger than 0.5"/yr, including 2MASS J02511490-0352459, which exceeds 2.0"/yr. VRI photometry from the 0.9 m and optical spectra from the 1.5 m indicate that the targets have V=11-22 mag and spectral types M3.0V-L3.0V. For 2MASS J23062928-0502285 (TRAPPIST-1), we present updated astrometry and photometric variability based on over 12 years of observations. Of the nine binaries in the sample, two promise mass determinations in the next decade: LHS 6167AB, an M4.5V system for which we present an accurate parallax placing the binary at 9.7 pc, and 2MASS J23515048-2537367AB, an M8.5V system at 21.1 pc for which we present the first evidence of an unseen, low-mass companion. Most importantly, Na I and K I gravity indicators, H{alpha} measurements, long-term photometric variability, locations on the H-R diagram, and kinematic assessments indicate that as many as 13 of the systems are young, including candidate members of young moving groups, with ages less than ~120 Myr.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/835
- Title:
- The Spitzer c2d survey of WTTSs. III.
- Short Name:
- J/ApJ/724/835
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 3.6 to 70um Spitzer photometry of 154 weak-line T Tauri stars (WTTSs) in the Chamaeleon, Lupus, Ophiuchus, and Taurus star formation regions, all of which are within 200pc of the Sun. For a comparative study, we also include 33 classical T Tauri stars which are located in the same star-forming regions. Spitzer sensitivities allow us to robustly detect the photosphere in the IRAC bands (3.6 to 8um) and the 24um MIPS band. In the 70um MIPS band, we are able to detect dust emission brighter than roughly 40 times the photosphere. These observations represent the most sensitive WTTSs survey in the mid- to far-infrared to date and reveal the frequency of outer disks (r=3-50AU) around WTTSs. The 70um photometry for half the c2d WTTSs sample (the on-cloud objects), which were not included in the earlier papers in this series, those of Padgett et al. (2006ApJ...645.1283P) and Cieza et al. (2007, Cat. J/ApJ/667/308) are presented here for the first time.
- ID:
- ivo://CDS.VizieR/J/AN/334/673
- Title:
- The stellar content of Trumpler 37
- Short Name:
- J/AN/334/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With an apparent cluster diameter of 1.5deg and an age of ~4Myr, Trumpler 37 is an ideal target for photometric monitoring of young stars as well as for the search of planetary transits, eclipsing binaries and other sources of variability. The YETI consortium has monitored Trumpler 37 throughout 2010 and 2011 to obtain a comprehensive view of variable phenomena in this region. In this first paper we present the cluster properties and membership determination as derived from an extensive investigation of the literature. We also compared the coordinate list to some YETI images. For 1872 stars we found literature data. Among them 774 have high probability of being member and 125 a medium probability. Based on infrared data we re-calculate a cluster extinction of 0.9-1.2mag. We can confirm the age and distance to be 3-5Myr and ~870pc. Stellar masses are determined from theoretical models and the mass function is fitted with a power-law index of {alpha}=1.90 (0.1-0.4M_{sun}_) and {alpha}=1.12 (1-10M_{sun}_).
- ID:
- ivo://CDS.VizieR/J/A+A/636/A46
- Title:
- The SUGAR model. Training dataset
- Short Name:
- J/A+A/636/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This analysis develops a new SNe Ia spectral energy distribution (SED) model, called the SUpernova Generator And Reconstructor (SUGAR), which improves the spectral description of SNe Ia, and consequently could improve the distance measurements. This model was constructed from SNe Ia spectral properties and spectrophotometric data from the Nearby Supernova Factory collaboration. In a first step, a principal component analysis-like method was used on spectral features measured at maximum light, which allowed us to extract the intrinsic properties of SNe Ia. Next, the intrinsic properties were used to extract the average extinction curve. Third, an interpolation using Gaussian processes facilitated using data taken at different epochs during the lifetime of an SN Ia and then projecting the data on a fixed time grid. Finally, the three steps were combined to build the SED model as a function of time and wavelength. This is the SUGAR model. The proper way to cite the data can be found at https://snfactory.lbl.gov/snf/data/index.html
- ID:
- ivo://CDS.VizieR/J/ApJ/838/150
- Title:
- The Taurus-Auriga ecosystem. I.
- Short Name:
- J/ApJ/838/150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The census of Taurus-Auriga has been assembled over seven decades and inherited the biases and incompleteness of the input studies. The unusual shape of its inferred initial mass function (IMF) and the existence of isolated disk-bearing stars suggest that additional (likely disk-free) members remain to be discovered. We therefore have begun a global reassessment of the census of Taurus-Auriga that exploits new data and better definitions of youth and kinematic membership. As a first step, we reconsider the membership of all disk-free candidate members from the literature with spectral type >=F0, 3h50min<{alpha}5h40min, and 14{deg}<{delta}<34{deg}. We combine data from the literature with Keck/HIRES and UH88/SNIFS spectra to test the membership of these candidates using the positions in the Hertzsprung-Russel diagram, proper motions, radial velocities, H{alpha}, lithium, and surface gravity. We find 218 confirmed or likely Taurus members, 160 confirmed or likely interlopers, and only 18 that lack sufficient evidence to draw firm conclusions. A significant fraction of these stars (81/218=37%) are not included in the most recent canonical member lists. There are few additional members to the immediate vicinity of the molecular clouds, preserving the IMFs that have been deemed anomalous in past work. Many of the likely Taurus members are instead distributed broadly across the search area. When combined with the known disk hosts, our updated census reveals two regimes: a high-density population with a high disk fraction (indicative of youth) that broadly traces the molecular clouds, and a low-density population with low disk fraction (hence likely older) that most likely represents previous generations of star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/759/112
- Title:
- The UV low-redshift intergalactic medium
- Short Name:
- J/ApJ/759/112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comprehensive catalog of ultraviolet (HST/STIS and FUSE) absorbers in the low-redshift intergalactic medium (IGM) at z<0.4. The catalog draws from much of the extensive literature on IGM absorption and reconciles discrepancies among several previous catalogs through a critical evaluation of all reported absorption features in light of new HST/COS data. We report on 746 H I absorbers down to a rest-frame equivalent width of 12m{AA} over a maximum redshift path length {Delta}z=5.38. We also confirm 111 O VI absorbers, 29 C IV absorbers, and numerous absorption lines due to other metal ions. We characterize the bivariate distribution of absorbers in redshift and column density as a power law, ({partial}^2^N/{partial}z{partial}N){propto}N^-{beta}^, where {beta}=2.08+/-0.12 for O VI and {beta}=1.68+/-0.03 for H I. Utilizing a more sophisticated accounting technique than past work, our catalog accounts for ~43% of the baryons: 24+/-2% in the photoionized Ly{alpha} forest and 19+/-2% in the warm-hot IGM as traced by O VI. We discuss the large systematic effects of various assumed metallicities and ionization states on these calculations, and we implement recent simulation results in our estimates.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/1076
- Title:
- The WHIQII survey: compact blue galaxies
- Short Name:
- J/ApJ/708/1076
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of the WIYN High Image Quality Indiana-Irvine (WHIQII) survey, we present 123 spectra of faint emission-line galaxies, selected to focus on intermediate redshift (0.4<~z<~0.8) galaxies with blue colors that appear physically compact on the sky. The sample includes 15 true Luminous Compact Blue Galaxies (LCBGs) and an additional 27 slightly less extreme emission-line systems. These galaxies represent a highly evolving class that may play an important role in the decline of star formation since z~1, but their exact nature and evolutionary pathways remain a mystery. Here, we use emission lines to determine metallicities and ionization parameters, constraining their intrinsic properties and state of star formation. Some LCBG metallicities are consistent with a "bursting dwarf" scenario, while a substantial fraction of others are not, further confirming that LCBGs are a highly heterogeneous population but are broadly consistent with the intermediate redshift field. In agreement with previous studies, we observe overall evolution in the luminosity-metallicity relation at intermediate redshift. Our sample, and particularly the LCBGs, occupies a region in the empirical R_23_-O_32_ plane that differs from luminous local galaxies and is more consistent with dwarf irregulars at the present epoch, suggesting that cosmic "downsizing" is observable in even the most fundamental parameters that describe star formation.
