- ID:
- ivo://CDS.VizieR/J/AJ/103/1987
- Title:
- Stars of very low metal abundance
- Short Name:
- J/AJ/103/1987
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations for 1044 stars located primarily in the southern Galactic hemisphere are reported; the stars were chosen from a list of candidate metal-deficient stars discovered in the HK objective-prism survey. Radial velocities and line indices based on the equivalent widths of Ca II, K, H-gamma and H-delta, and the CH G band are reported. Estimates of metallicity for 874 stars with derived abundances less than -0.5 are presented.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/147/136
- Title:
- Stars of very low metal abundance. VI. Abundances
- Short Name:
- J/AJ/147/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coude Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, and the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by {approx}0.25dex for red giants and {approx}0.04dex for subgiants. Our sample contains 19 stars with [Fe/H]<=-3.5, 84 stars with [Fe/H]<=-3.0, and 210 stars with [Fe/H]<=-2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H]<=-2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.
- ID:
- ivo://CDS.VizieR/J/A+A/535/A55
- Title:
- 4 stars with long-period planets
- Short Name:
- J/A+A/535/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of four new long-period planets within the HARPS high-precision sample: HD137388b (Msini=0.22M_Jup_), HD204941b (Msini=0.27M_Jup_), HD7199b (Msini=0.29M_Jup_), HD7449b (Msini=1.04M_Jup_). A long-period companion, probably a second planet, is also found orbiting HD7449. Planets around HD137388, HD204941, and HD7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD7449b. All these planets were discovered even though their hosting stars have clear signs of activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/891/23
- Title:
- Stellar abundances from LAMOST MRS (SPCAnet)
- Short Name:
- J/ApJ/891/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fundamental stellar atmospheric parameters (Teff and logg) and 13 chemical abundances are derived for medium-resolution spectroscopy from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium Resolution Survey (MRS) data sets with a deep-learning method. The neural networks we designed, named SPCANet, precisely map LAMOST MRS spectra to stellar parameters and chemical abundances. The stellar labels derived by SPCANet have precisions of 119K for Teff and 0.17dex for logg. The abundance precision of 11 elements including [C/H], [N/H], [O/H], [Mg/H], [Al/H], [Si/H], [S/H], [Ca/H], [Ti/H], [Cr/H], [Fe/H], and [Ni/H] are 0.06 {\sim} 0.12 dex, while that of [Cu/H] is 0.19dex. These precisions can be reached even for spectra with signal-to-noise ratios as low as 10. The results of SPCANet are consistent with those from other surveys such as APOGEE, GALAH, and RAVE, and are also validated with the previous literature values including clusters and field stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/275
- Title:
- Stellar activity of late-type stars
- Short Name:
- J/A+AS/142/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a spectroscopic CaII H&K survey of 1058 late-type stars selected from a color-limited subsample of the Hipparcos (Cat. <I/239>) catalog. Out of these 1058 stars, 371 stars were found to show significant H&K emission, most of them previously unknown; 23% with strong emission, 36% with moderate emission, and 41% with weak emission. These spectra are used to determine absolute H&K emission-line fluxes, radial velocities, and equivalent widths of the luminosity-sensitive Sr II line at 4077{AA}. Red-wavelength spectroscopic and Stroemgren y photometric follow-up observations of the 371 stars with H&K emission are used to additionally determine the absolute H{alpha}-core flux, the lithium abundance from the Li I 6708{AA} equivalent width, the rotational velocity vsini, the radial velocity, and the light variations and its periodicity.
- ID:
- ivo://CDS.VizieR/J/ApJS/127/39
- Title:
- Stellar and gas kinematics in early-type galaxies
- Short Name:
- J/ApJS/127/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data on stellar and gaseous kinematics of 14 gas-rich early-type galaxies. File galaxies.dat contains the list of observed galaxies, with coordinates, distance, absolute magnitude, and position angles. File stellar.dat contains stellar rotation curves and velocity dispersion profiles. File gaseous.dat contains the gaseous velocity profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/360/439
- Title:
- Stellar and ionized gas kinematics in NGC 4672
- Short Name:
- J/A+A/360/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the case of the early-type disk galaxy NGC 4672 as a new example of a galaxy characterized by the orthogonal geometrical decoupling between bulge and disk. The morphological features of this galaxy are discussed as well as the velocity curves and velocity dispersion profiles of stars and ionized gas along both its major and minor axis. We conclude that NGC 4672 has structural (i.e. a bulge elongated perpendicularly to the disk) and kinematical (i.e. a stellar core rotating perpendicularly to the disk) properties similar to those of the Sa NGC 4698. The presence of the isolated core suggests that the disk component is the end result of the acquisition of external material in polar orbits around a pre-existing oblate spheroid as in the case of the ring component of AM 2020-504, the prototype of polar ring ellipticals.
- ID:
- ivo://CDS.VizieR/J/A+A/382/488
- Title:
- Stellar and ionized gas kinematics in NGC 2855
- Short Name:
- J/A+A/382/488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present major and minor-axis kinematics of stars and ionized gas as well as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the nuclear regions of this unbarred and apparently undisturbed spiral galaxy the gas is rotating perpendicularly to the galaxy disk. We suggest that this kinematically-decoupled component is the signature of an acquisition process in the history of this galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJS/251/29
- Title:
- Stellar bow shock nebulae spectroscopic obs.
- Short Name:
- J/ApJS/251/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arcuate mid-infrared nebulae known as stellar bow shock nebulae (SBNe) have been previously hypothesized to be supported by the strong stellar winds and/or luminosity of massive early-type stars. We present an optical spectroscopic survey of 84 stars identified from mid-infrared images as candidate SBN-supporting stars. Eighty-one of 84 sources, 96%, are O or early-B spectral types. K-band luminosities for a larger sample of 289 stars at the centers of bow shock nebulae are overwhelmingly consistent with OB stars. This affirms both that SBNe are supported by massive stars and that arcuate mid-infrared nebulae are reliable indicators of the presence of a massive star. The radial velocity dispersions of these systems and detections of double-lined systems indicate that at least 27 of the 74 systems with multiple observations (>36%) are candidate multiple-star systems. This rate is consistent with observed multiplicity rates of field OB stars detected with similar radial velocity surveys and lower than, but not inconsistent with, the multiplicity rates of OB stars in clusters and associations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/4039
- Title:
- Stellar kinematics for NGC 2859 and NGC 4371
- Short Name:
- J/MNRAS/446/4039
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of nine S0-Sb galaxies which have (photometric) bulges consisting of two distinct components. The outer component is a flattened, kinematically cool, disc-like structure: a 'discy pseudo-bulge'. Embedded inside is a rounder, kinematically hot spheroidal structure: a `classical bulge'. This indicates that pseudo-bulges and classical bulges are not mutually exclusive phenomena: some galaxies have both. The discy pseudo-bulges almost always consist of an exponential disc (scalelengths=125-870 pc, mean size ~440 pc) with one or more disc-related subcomponents: nuclear rings, nuclear bars, and/or spiral arms. They constitute 11-59 percent of the galaxy stellar mass (mean PB/T=0.33), with stellar masses ~7x10^9^-9x10^10^ M_{sun}_. The classical-bulge components have Sersic indices of 0.9-2.2, effective radii of 25-430 pc and stellar masses of 5x10^8^-3x10^10^ M_{sun}_; they are usually <10 percent of the galaxy's stellar mass (mean B/T=0.06). The classical bulges do show rotation, but are clearly kinematically hotter than the discy pseudo-bulges. Dynamical modelling of three systems indicates that velocity dispersions are isotropic in the classical bulges and equatorially biased in the discy pseudo-bulges. In the mass-radius and mass-stellar mass density planes, classical-bulge components follow sequences defined by ellipticals and (larger) classical bulges. Discy pseudo-bulges also fall on this sequence; they are more compact than large-scale discs of similar mass. Although some classical bulges are quite compact, they are as a class clearly distinct from nuclear star clusters in both size and mass; in at least two galaxies they coexist with nuclear clusters. Since almost all the galaxies in this study are barred, they probably also host boxy/peanut-shaped bulges (vertically thickened inner parts of bars). NGC 3368 shows isophotal evidence for such a zone just outside its discy pseudo-bulge, making it a clear case of a galaxy with all three types of 'bulge'.
