- ID:
- ivo://CDS.VizieR/J/AJ/161/285
- Title:
- Absorption & emission lines and RVel for vA 351
- Short Name:
- J/AJ/161/285
- Date:
- 08 Mar 2022
- Publisher:
- CDS
- Description:
- We extend results first announced by Franz et al., that identified vA351=H346 in the Hyades as a multiple star system containing a white dwarf. With Hubble Space Telescope Fine Guidance Sensor fringe tracking and scanning, and more recent speckle observations, all spanning 20.7years, we establish a parallax, relative orbit, and mass fraction for two components, with a period, P=2.70yr and total mass 2.1M{sun}. With ground-based radial velocities from the McDonald Observatory Otto Struve 2.1m Telescope Sandiford Spectrograph, and Center for Astrophysics Digital Speedometers, spanning 37 years, we find that component B consists of BC, two M-dwarf stars orbiting with a very short period (P_BC_=0.749days), having a mass ratio M_C_/M_B_=0.95. We confirm that the total mass of the system can only be reconciled with the distance and component photometry by including a fainter, higher-mass component. The quadruple system consists of three M dwarfs (A, B, C) and one white dwarf (D). We determine individual M-dwarf masses M_A_=0.53{+/-}0.10M{sun}, M_B_=0.43{+/-}0.04M{sun}, and M_C_=0.41{+/-}0.04M{sun}. The white dwarf mass, 0.54{+/-}0.04M{sun}, comes from cooling models, an assumed Hyades age of 670Myr, and consistency with all previous and derived astrometric, photometric, and radial velocity results. Velocities from H{alpha} and HeI emission lines confirm the BC period derived from absorption lines, with similar (HeI) and higher (H{alpha}) velocity amplitudes. We ascribe the larger H{alpha} amplitude to emission from a region each component shadows from the other, depending on the line of sight.
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- ID:
- ivo://CDS.VizieR/J/A+A/287/927
- Title:
- Abundances for lines of n-capture in 19 stars
- Short Name:
- J/A+A/287/927
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1029
- Title:
- Abundances in OGLE-2007-BLG-349S
- Short Name:
- J/ApJ/682/1029
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an abundance analysis based on high-dispersion and high signal-to-noise ratio Keck spectra of a very highly microlensed Galactic bulge dwarf, OGLE-2007-BLG-349S, with Teff~5400K. The amplification at the time the spectra were taken ranged from 350 to 450. This bulge star is highly enhanced in metallicity with [Fe/H]=+0.51+/-0.09dex. The abundance ratios for the 28 species of 26 elements for which features could be detected in the spectra are almost all solar. In particular, there is no evidence for enhancement of any of the {alpha}-elements, including O and Mg. We conclude that the high [Fe/H] seen in this star, when combined with the equally high [Fe/H] derived in previous detailed abundance analysis of two other Galactic bulge dwarfs, both also highly magnified by microlensing, implies that the median metallicity in the Galactic bulge is very high. We thus infer that many previous estimates of the metallicity distribution in the Galactic bulge have substantially underestimated the mean Fe metallicity there due to sample bias, and suggest a candidate mechanism for such. If our conjecture proves valid, it may be necessary to update the calibrations for the algorithms used by many groups to interpret spectra and broadband photometry of the integrated light of very metal-rich old stellar populations, including luminous elliptical galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/508/L17
- Title:
- Abundances in solar analogs
- Short Name:
- J/A+A/508/L17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive the abundance of 19 elements in a sample of 64 stars with fundamental parameters very similar to solar, which minimizes the impact of systematic errors in our spectroscopic 1D-LTE differential analysis, using high-resolution (R~60000), high signal-to-noise ratio (S/N~200) spectra. The estimated errors in the elemental abundances relative to solar are as small as ~0.025dex. The abundance ratios [X/Fe] as a function of [Fe/H] agree closely with previously established patterns of Galactic thin-disk chemical evolution.
- ID:
- ivo://CDS.VizieR/J/AZh/88/750
- Title:
- Abundances in stars of galactic sub-structures
- Short Name:
- J/AZh/88/750
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined abundances of copper, zinc, sodium, and aluminium in the atmospheres of 172 F, G, and K dwarf stars (-1.0<[Fe/H]<0.3) belonging to the Galaxy's thin and thick disks and to the Hercules moving group. Our observations were performed with the ELODIE echelle spectrometer on the 1.93-m telescope of the Haute ProvenceObservatory, with a resolving power of R=42000 and signal-to-noise ratio S/N>100. The Na, Al, Cu, and Zn abundances were derived in an LTE approximation; the synthetic spectrum for the copper lines was calculated taking into account super-fine structure of the lines. We analyzed the abundances of these elements as a function of metallicity [Fe/H] for stars of the thin and thick disks of the Galaxy and the Hercules moving group. The Cu abundances and their trends with metallicity are essentially the same in the three studied sub-structures. The mean Al and Zn abundances for stars of the thin and thick disks differ significantly.
- ID:
- ivo://CDS.VizieR/J/AJ/133/694
- Title:
- Abundances in the HR 1614 moving group
- Short Name:
- J/AJ/133/694
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present abundances for a sample of F, G, and K dwarfs of the HR 1614 moving group based on high-resolution, high signal-to-noise ratio spectra from the Anglo-Australian Telescope UCLES instrument. Our sample includes stars from Feltzing and Holmberg, as well as from Eggen. Abundances were derived for Na, Mg, Al, Si, Ca, Mn, Fe, Ni, Zr, Ba, Ce, Nd, and Eu.
- ID:
- ivo://CDS.VizieR/J/AJ/153/21
- Title:
- Abundances in the local region. II. F, G, and K dwarfs
- Short Name:
- J/AJ/153/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Parameters and abundances have been derived for 1002 stars of spectral types F, G, and K, and luminosity classes IV and V. After culling the sample for rotational velocity and effective temperature, 867 stars remain for discussion. Twenty-eight elements are considered in the analysis. The {alpha}, iron-peak, and Period 5 transition metal abundances for these stars show a modest enhancement over solar averaging about 0.05dex. The lanthanides are more abundant, averaging about +0.2dex over solar. The question is: Are these stars enhanced, or is the Sun somewhat metal-poor relative to these stars? The consistency of the abundances derived here supports an argument for the latter view. Lithium, carbon, and oxygen abundances have been derived. The stars show the usual lithium astration as a function of mass/temperature. There are more than 100 planet-hosts in the sample, and there is no discernible difference in their lithium content, relative to the remaining stars. The carbon and oxygen abundances show the well-known trend of decreasing [x/Fe] ratio with increasing [Fe/H].
- ID:
- ivo://CDS.VizieR/J/AJ/155/111
- Title:
- Abundances in the local region. III. Southern dwarfs
- Short Name:
- J/AJ/155/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar parameters and abundances have been derived from a sample of 907 F, G, and K dwarfs. The high-resolution, high signal-to-noise spectra utilized were acquired with the HARPS spectrograph of the European Southern Observatory. The stars in the sample with -0.2<[Fe/H]<+0.2 have abundances that strongly resemble that of the Sun, except for the lithium content and the lanthanides. Near the solar temperature, stars show two orders of magnitude range in lithium content. The average content of stars in the local region appears to be enhanced at about the +0.1 level relative to the Sun for the lanthanides. There are over 100 planet hosts in this sample, and there is no discernible difference between them and the non-hosts regarding their lithium content.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/66
- Title:
- Abundances in two Galactic bulge stars
- Short Name:
- J/ApJ/699/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present abundance analyses based on high dispersion and high signal-to-noise ratio Magellan spectra of two highly microlensed Galactic bulge stars in the region of the main-sequence turnoff with T_eff_~5650K. We find that MOA-2008-BLG-310S has [Fe/H]^8^=+0.41+/-0.09dex and MOA-2008-BLG-311S has +0.26+/-0.09dex. The abundance ratios for the ~20 elements for which features could be detected in the spectra of each of the two stars follow the trends with [Fe/H] found among samples of bulge giants. Combining these two bulge dwarfs with the results from previous abundance analysis of four other Galactic bulge turnoff region stars, all highly magnified by microlensing, gives a mean [Fe/H] of +0.29dex. This implies that there is an inconsistency between the Fe-metallicity distribution of the microlensed bulge dwarfs and that derived by the many previous estimates based on surveys of cool, luminous bulge giants, which have mean [Fe/H]~-0.1dex.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A28
- Title:
- Abundances of dwarfs and giants in 2 open clusters
- Short Name:
- J/A+A/515/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been suggested that the classical chemical analysis may be affected by systematic errors that would introduce abundance differences between dwarfs and giants. For some elements, the abundance difference could be real. We address the issue by observing 2 solar-type dwarfs in NGC 5822 and 3 in IC 4756, and comparing their composition with that of 3 giants in either of the aforementioned clusters. We determine iron abundance and stellar parameters for dwarf stars. Then, abundances of calcium, sodium, nickel, titanium, aluminium, chromium, and silicon were determined for both giants and dwarfs. The standard equivalent width analysis was performed differentially with respect to the Sun. We find an iron abundance for dwarf stars equal to solar to within the margins of error for IC 4756, and slightly above for NGC 5822 ([Fe/H]=0.01 and 0.05dex respectively). We show that, for sodium, silicon, and titanium, abundances of giants are significantly higher than those of the dwarfs of the same cluster (about 0.15, 0.15, and 0.35dex). Other elements may also undergo some enhanced, but all within 0.1dex.
