- ID:
- ivo://CDS.VizieR/J/MNRAS/372/163
- Title:
- Activity indices for southern stars
- Short Name:
- J/MNRAS/372/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in the Southern hemisphere. The stars are targets or candidates to be targets for the Anglo-Australian Planet Search. CaII H&K line cores were used to derive activity indices for all of these objects. The indices were converted to the Mt. Wilson system of measurements and logR'_HK_ values determined. A number of these stars had no previously derived activity indices. In addition, we have also included the stars from Tinney et al. (2002MNRAS.332..759T) using our Mt. Wilson calibration. The radial-velocity instability (also known as jitter) level was determined for all 21 planet-host stars in our data set. We find the jitter to be at a level considerably below the radial-velocity signatures in all but one of these systems. 19 stars from our sample were found to be active (logR'_HK_>-4.5) and thus have high levels of jitter. Radial-velocity analysis for planetary companions to these stars should proceed with caution.
1 - 8 of 8
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- ID:
- ivo://CDS.VizieR/J/other/RAA/11.924
- Title:
- Atmospheric parameters for 771 stars
- Short Name:
- J/other/RAA/11.9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A number of spectroscopic surveys have been carried out or are planned to study the origin of the Milky Way. Their exploitation requires reliable automated methods and softwares to measure the fundamental parameters of the stars. Adopting the ULySS package, we have tested the effect of different resolutions and signal-to-noise ratios (SNR) on the measurement of the stellar atmospheric parameters (effective temperature Teff, surface gravity logg, and metallicity [Fe/H]). We show that ULySS is reliable to determine these parameters with medium-resolution spectra (R~2000). Then, we applied the method to measure the parameters of 771 stars selected in the commissioning database of the Guoshoujing Telescope (GSJT). The results were compared with the SDSS/SEGUE Stellar Parameter Pipeline (SSPP), and we derived precisions of 167K, 0.34dex, and 0.16dex for Teff, logg and [Fe/H] respectively. Furthermore, 120 of these stars are selected to construct the primary stellar spectra template library (Version 1.0) of GSJT, and will be deployed as basic ingredients for the GSJT automated parametrization pipeline.
- ID:
- ivo://CDS.VizieR/J/PASJ/57/27
- Title:
- Atmospheric parameters of nearby F-K stars
- Short Name:
- J/PASJ/57/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on a collection of high-dispersion spectra obtained at Okayama Astrophysical Observatory, the atmospheric parameters (Teff, logg, vt, and [Fe/H]) of 160 mid-F through early-K stars were extensively determined by the spectroscopic method using the equivalent widths of Fe I and Fe II lines along with the numerical technique of Takeda et al. (2002PASJ...54..451T). The results are comprehensively discussed and compared with the parameter values derived by different approaches (e.g., photometric colors, theoretical evolutionary tracks, Hipparcos parallaxes, etc.) as well as with the published values found in various literature. It has been confirmed that our purely spectroscopic approach yields fairly reliable and consistent results.
- ID:
- ivo://CDS.VizieR/J/A+AS/99/291
- Title:
- CO and HCN observations of circumstellar envelopes
- Short Name:
- J/A+AS/99/291
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched the literature for all observations of the ^12^CO(1-0), ^12^CO(2-1), and HCN(1-0) lines in circumstellar envelopes of late type stars published between January 1985 and September 1992. We report data for 1361 observations (stellar velocity, expansion velocity, peak intensity, integrated area, noise level). This CO-HCN sample now contains 444 sources. 184 are identified as oxygen-rich, 205 as carbon-rich, and there are 9 S stars. About 85% of the sources are AGB stars. There are 32 planetary nebulae and about thirty post-AGB stars candidates. Besides results of millimeter observations, we also list identifications, coordinates, IRAS data, chemical and spectral types for every source. For AGB stars, we have estimated (or compiled) bolometric fluxes and distances for 349 sources, and mass loss rates deduced from CO results for 324 sources, taking into account the influence of the CO photodissociation radius. We also list mass loss rates derived from detailed models of CO emission which we could find in the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/427/2180
- Title:
- GALEX survey subdwarf atmospheric parameters
- Short Name:
- J/MNRAS/427/2180
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an update of our low-resolution spectroscopic follow-up and model atmosphere analysis of hot subdwarf stars from the Galaxy Evolution Explorer (GALEX) survey. Targets were selected on the basis of colour indices calculated from the GALEX GR6 N_UV_, Guide Star Catalogue (GSC2.3.2) Vand the Two Micron All Sky Survey (2MASS) J and H photometry. High signal-to-noise ratio spectra were obtained at the European Southern Observatory (ESO) and the Kitt Peak National Observatory (KPNO) over the course of three years. Detailed H, He and CNO abundance analysis helped us improve our T_eff_, logg and He abundance determination and to constrain CNO abundances. We processed 191 observations of 180 targets and found 124 sdB and 42 sdO stars in this sample while some blue horizontal branch stars were also found in this programme. With quantitative binary decomposition of 29 composite spectra we investigated the incidence of A, F and G type companions. The incidence of late G and K type companions and their effects on subdwarf atmospheric parameters were also examined.
- ID:
- ivo://CDS.VizieR/J/PASJ/57/45
- Title:
- Lithium abundances of F-K stars
- Short Name:
- J/PASJ/57/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive profile-fitting analysis was performed for the Li(+Fe) 6707-6708{AA} feature of nearby 160 F-K dwarfs/subgiants (including 27 planet-host stars) in the Galactic disk (7000K>~Teff>~5000K, -1<~[Fe/H]<~+0.4), in order to establish the photospheric lithium abundances of these stars. The non-LTE effect (though quantitatively insignificant) was taken into account based on our statistical equilibrium calculations, which were carried out on an adequate grid of models. Our results confirmed most of the interesting observational characteristics revealed by recently published studies, such as the bimodal distribution of the Li abundances for stars at Teff>~6000K, the satisfactory agreement of the upper envelope of the A(Li) vs. [Fe/H] distribution with the theoretical models, the existence of a positive correlation between A(Li) and the stellar mass, and the tendency of lower lithium abundances of planet-host stars (as compared to stars without planets) at the narrow ``transition'' region of 5900K>~Teff>~5800K. The solar Li abundance derived from this analysis is 0.92 (H=12.00), which is by 0.24dex lower than the widely referenced standard value of 1.16.
- ID:
- ivo://CDS.VizieR/J/AZh/80/458
- Title:
- Sodium abundances in stellar atmospheres
- Short Name:
- J/AZh/80/458
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The non-LTE sodium abundances of 100 dwarf, giant and subgiant stars with metallicities -3<[Fe/H]<0.3 are determined using high-dispersion spectra with high signal-to-noise ratios.
- ID:
- ivo://CDS.VizieR/J/AZh/88/1217
- Title:
- Solar-like activity of low-mass stars
- Short Name:
- J/AZh/88/1217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An analysis of data on chromospheric activity obtained in the framework of exoplanet-search programs is presented. Observations of 1334 stars showing that the chromospheric activity of the Sun is clearly higher than for the vast majority of stars in the solar vicinity are used. A comparison of chromospheric and coronal activity led to the identification of a significant group of stars with a low level of chromospheric activity, whose coronal radiation spans wide ranges.
