Search

Start Over Capability Type Simple Cone Search
14101. Spectroscopic orbits for late-type stars. II.
ID:
ivo://CDS.VizieR/J/AJ/156/117
Title:
Spectroscopic orbits for late-type stars. II.
Short Name:
J/AJ/156/117
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have determined spectroscopic orbital elements for 13 systems - 10 single-lined binaries and three double-lined binaries. For the three binaries with previously published spectroscopic orbits, we have computed improved or comparable elements. While two systems have relatively short periods between 10 and 19 days, the remaining systems have much longer periods ranging from 604 to 9669 days. One of the single-lined systems, HD 142640, shows both short-period and long-period velocity variations and so is triple. For three systems - HD 59380, HD 160933, and HD 161163 - we have combined our spectroscopic results with Hipparcos astrometric observations to obtain astrometric orbits. For HD 14802 we have determined a joint orbital solution from spectroscopic velocities and interferometric observations. The orbits given here will be useful in combination with future interferometric and Gaia satellite observations.
14102. Spectroscopic orbits for three binaries
ID:
ivo://CDS.VizieR/J/ApJ/466/415
Title:
Spectroscopic orbits for three binaries
Short Name:
J/ApJ/466/415
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present orbital solutions for three low-amplitude spectroscopic binaries discovered in a sample of 20 solar-type IAU radial velocity standard stars observed with the Digital Speedometers at the Harvard- Smithsonian Center for Astrophysics. We update the orbital solutions for HD 114762 and HD 140913, and present a preliminary new solution for HD 29587. For all three orbits, the minimum mass for the secondary is less than 0.08M_{sun}_, the borderline between stellar and substellar masses. We consider the probability that all three binaries have small enough inclination angles so that their companions are above the substellar limit. To do so, we treat the 20 IAU standards as a sample drawn from a population of binaries with a mass-ratio distribution that does not allow any substellar companions. We calculate the probability that such a sample could still have three binaries, with the low-amplitude orbits actually found within the IAU sample. We show that this probability is small, depending on the specific mass-ratio distribution. For example, a flat mass-ratio distribution that assumes there are no substellar companions can be excluded at a high confidence level, 99.7%. We further show that our three detections may imply that the secondary-mass distribution rises near the substellar limit. However, the observations do not yet allow us to distinguish whether the unseen companions of HD 114762, HD 140913, and HD 29587 have stellar or substellar masses. In particular, recent attempts to estimate the mass of the companion of HD 114762 based on assumptions about the intrinsic rotation of the primary are inconclusive, and the companion could easily have a mass as low as 0.02M_{sun}_. We compare our three detections with the null results of four very precise radial velocity searches for substellar companions. The difference is indeed puzzling but can be accounted for if just a small fraction of the solar-type stars, of the order of a few percent, have companions with masses near the substellar limit.
14103. Spectroscopic parameters for 313 M dwarfs
ID:
ivo://CDS.VizieR/J/A+A/649/A147
Title:
Spectroscopic parameters for 313 M dwarfs
Short Name:
J/A+A/649/A147
Date:
22 Feb 2022
Publisher:
CDS
Description:
The scientific community's interest on the stellar parameters of M dwarfs has been increasing over the last few years, with potential applications ranging from galactic characterization to exoplanet detection. The main motivation for this work is to develop an alternative and objective method to derive stellar parameters for M dwarfs using the H-band spectra provided by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). Synthetic spectra generated with iSpec, Turbospectrum, MARCS models atmospheres and a custom made line list including over 1000000 water lines, are compared to APOGEE observations, and parameters are determined through {chi}^2^ minimization. Spectroscopic parameters (Teff, [M/H], logg, v_mic_) are presented for a sample of 313 M dwarfs, obtained from their APOGEE H-band spectra. The generated synthetic spectra reproduce observed spectra to a high accuracy level. The impact of the spectra normalization on the results are analyzed as well. Our output parameters are compared with the ones obtained with APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) for the same stellar spectrum, and we find that the values agree within the expected uncertainties. Comparisons with other previous near-infrared and optical literature are also available, with median differences within our estimated uncertainties found in most cases. Possible reasons for these differences are explored. The full H-band line list, the line selection for the synthesis, and the synthesized spectra are available for download, as are the calculated stellar parameters.
14104. Spectroscopic parameters of 451 HARPS-GTO stars
ID:
ivo://CDS.VizieR/J/A+A/487/373
Title:
Spectroscopic parameters of 451 HARPS-GTO stars
Short Name:
J/A+A/487/373
Date:
21 Oct 2021
Publisher:
CDS
Description:
To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) "high precision" sample. Spectroscopic stellar parameters were measured using high signal-to-noise (S/N) spectra acquired with the HARPS spectrograph. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and the recent ARES code for measuring line equivalent widths. We show that our results agree well with those ones presented in the literature (for stars in common). We present a useful calibration for the effective temperature as a function of the index color B-V and [Fe/H]. We use our results to study the metallicity-planet correlation, namely for very low mass planets. The results presented here suggest that in contrast to their jovian counterparts, Neptune-like planets do not form preferentially around metal-rich stars. The ratio of Jupiter-to-Neptune is also an increasing function of stellar metallicity. These results are discussed in the context of the core-accretion model for planet formation.
14105. Spectroscopic parameters of O-type stars
ID:
ivo://CDS.VizieR/J/A+A/613/A65
Title:
Spectroscopic parameters of O-type stars
Short Name:
J/A+A/613/A65
Date:
21 Oct 2021
Publisher:
CDS
Description:
The IACOB and OWN surveys are two ambitious complementary observational projects which have made available a large multi-epoch spectroscopic database of optical high resolution spectra of Galactic massive O-type stars. As a first step in the study of the full sample of (more than 350) O stars surveyed by the IACOB and OWN projects, we have performed the quantitative spectroscopic analysis of a subsample of 128 stars included in the modern grid of O-type standards for spectral classification. The sample comprises stars with spectral types in the range O3-O9.7 and covers all luminosity classes. We use the semi-automatized iacob-broad and iacob-gbat/fastwind tools to determine the complete set of spectroscopic parameters that can be obtained from the optical spectrum of O-type stars. A quality flag is assigned to the outcome of the iacob- gbat/fastwind analysis for each star, based on a visual evaluation of how the synthetic spectrum of the best fitting fastwind model reproduces the observed spectrum. We also benefit from the multi-epoch character of the IACOB and OWN surveys to perform a spectroscopic variability study of the complete sample, providing two different flags for each star accounting for spectroscopic binarity as well as variability of the main wind diagnostic lines.
14106. Spectroscopic parameters of Seyfert nuclei
ID:
ivo://CDS.VizieR/J/ApJS/112/315
Title:
Spectroscopic parameters of Seyfert nuclei
Short Name:
J/ApJS/112/315
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have completed an optical spectroscopic survey of the nuclear regions (r<=200pc) of a large sample of nearby galaxies. Although the main objectives of the survey are to search for low-luminosity active galactic nuclei and to quantify their luminosity function, the database can be used for a variety of other purposes. This paper presents measurements of the spectroscopic parameters for the 418 emission-line nuclei, along with a compilation of the global properties of all 486 galaxies in the survey. Stellar absorption generally poses a serious obstacle to obtaining accurate measurement of emission lines in nearby galactic nuclei. We describe a procedure for removing the starlight from the observed spectra in an efficient and objective manner. The main parameters of the emission lines (intensity ratios, fluxes, profile widths, and equivalent widths) are measured and tabulated, as are several stellar absorption-line and continuum indices useful for studying the stellar population. Using standard nebular diagnostics, we determine the probable ionization mechanisms of the emission-line objects. The resulting spectral classifications provide extensive information on the demographics of emission-line nuclei in the nearby regions of the universe. This new catalog contains over 200 objects showing spectroscopic evidence for recent star formation and an equally large number of active galactic nuclei, including 46 that show broad H{alpha} emission. These samples will serve as the basis of future studies of nuclear activity in nearby galaxies.
14107. Spectroscopic parameters of stars (SPECIES). I.
ID:
ivo://CDS.VizieR/J/A+A/615/A76
Title:
Spectroscopic parameters of stars (SPECIES). I.
Short Name:
J/A+A/615/A76
Date:
21 Oct 2021
Publisher:
CDS
Description:
The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and characteristics of their companion(s). Our aims are to develop a community tool that allows the automated calculation of stellar parameters for a large number of stars, using high resolution echelle spectra and minimal photometric magnitudes, and introduce the first catalogue of these measurements in this work. We measured the equivalent widths of several iron lines and used them to solve the radiative transfer equation assuming local thermodynamic equilibrium in order to obtain the atmospheric parameters (Teff, [Fe/H], logg, and {xi}_t). We then used these values to derive the abundance of 11 chemical elements in the stellar photosphere (Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, Cu, and Zn). Rotation and macroturbulent velocity were obtained using temperature calibrators and synthetic line profiles to match the observed spectra isochrones, we were able to derive the mass, radius, and age for each star using a Bayesian approach. SPECIES obtains bulk parameters that are in good agreement with measured values from different existing catalogues, including when different methods are used to derive them. We find discrepancies in the chemical abundances for some elements with respect to other works, which could be produced by differences in Teff, or in the line list or the atomic line data used to derive them. We also obtained analytic relations to describe the correlations between different parameters, and we implemented new methods to better handle these correlations, which provides a better description of the uncertainties associated with the measurements.
14108. Spectroscopic properties for 107 stars
ID:
ivo://CDS.VizieR/J/MNRAS/468/4151
Title:
Spectroscopic properties for 107 stars
Short Name:
J/MNRAS/468/4151
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report results from the high-resolution spectral analysis of the 107 metal-rich (mostly [Fe/H]>=7.67dex) target stars from the Calan-Hertfordshire Extrasolar Planet Search programme observed with HARPS. Using our procedure of finding the best fit to the absorption line profiles in the observed spectra, we measure the abundances of Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu and Zn, and then compare them with known results from different authors. Most of our abundances agree with these works at the level of +/-0.05dex or better for the stars we have in common. However, we do find systematic differences that make direct inferences difficult. Our analysis suggests that the selection of line lists and atomic line data along with the adopted continuum level influence these differences the most. At the same time, we confirm the positive trends of abundances versus metallicity for Na, Mn, Ni and, to a lesser degree, Al. A slight negative trend is observed for Ca, whereas Si and Cr tend to follow iron. Our analysis allows us to determine the positively skewed normal distribution of projected rotational velocities with a maximum peaking at 3km/s. Finally, we obtained a Gaussian distribution of microturbulent velocities that has a maximum at 1.2km/s and a full width at half-maximum {Delta}v_1/2_=0.35km/s, indicating that metal-rich dwarfs and subgiants in our sample have a very restricted range in microturbulent velocity.
14109. Spectroscopic properties of BOSS compact galaxies
ID:
ivo://CDS.VizieR/J/ApJ/793/39
Title:
Spectroscopic properties of BOSS compact galaxies
Short Name:
J/ApJ/793/39
Date:
21 Oct 2021
Publisher:
CDS
Description:
Massive compact systems at 0.2<z<0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ~200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z~0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2<z<0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0<z<2.
14110. Spectroscopic properties of cool stars. I.
ID:
ivo://CDS.VizieR/J/ApJS/159/141
Title:
Spectroscopic properties of cool stars. I.
Short Name:
J/ApJS/159/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a uniform catalog of stellar properties for 1040 nearby F, G, and K stars that have been observed by the Keck, Lick, and AAT planet search programs. Fitting observed echelle spectra with synthetic spectra yielded effective temperature, surface gravity, metallicity, projected rotational velocity, and abundances of the elements Na, Si, Ti, Fe, and Ni, for every star in the catalog. Combining V-band photometry and Hipparcos parallaxes with a bolometric correction based on the spectroscopic results yielded stellar luminosity, radius, and mass. Interpolating Yonsei-Yale isochrones to the luminosity, effective temperature, metallicity, and {alpha}-element enhancement of each star yielded a theoretical mass, radius, gravity, and age range for most stars in the catalog.

Limit your search

more »

more »

more »

more »

more »

more »