- ID:
- ivo://CDS.VizieR/J/AJ/152/73
- Title:
- Stellar nuclei and bulges of nearby S0 galaxies
- Short Name:
- J/AJ/152/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of the Isaac Newton Group. I also estimate the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with the running tilted-ring technique, I have found seven new cases of inner polar disks. Together with those, the frequency of inner polar disks in nearby S0 galaxies reaches 10%, which is much higher than the frequency of large-scale polar rings. Interestingly, the properties of the nuclear stellar populations in the inner polar ring hosts are statistically the same as those in the whole S0 sample, implying similar histories of multiple gas-accretion events from various directions.
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- ID:
- ivo://CDS.VizieR/J/A+A/425/927
- Title:
- Stellar objects in the Serpens cloud field
- Short Name:
- J/A+A/425/927
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near infrared (J, H and Ks) observations of a 5'x10' sample field in the Serpens Star Formation region obtained with SOFI at the NTT. These observations are sensitive enough to detect a 20M_Jup_ brown dwarf through an extinction of A_V_~16 and are used to build an infrared census of this field in the cluster. From photometry and mass-luminosity models, we have developed a detailed methodology to extract quantitative parameters (distance modulus, extinction, spectral type, masses) for objects observed towards and inside the Serpens molecular cloud. An extinction map of the region is derived allowing us to disentangle cloud members from background field objects. Luminosities and masses for 14 low-mass stars and substellar object candidate members of the cluster are derived.
- ID:
- ivo://CDS.VizieR/J/AJ/159/230
- Title:
- Stellar occultation by (541132) Leleakuhonua
- Short Name:
- J/AJ/159/230
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A stellar occultation by the extreme large-perihelion trans-Neptunian object (541132)-Leleakuhonua (also known by the provisional designation of 2015TG_387_) was predicted by the Lucky Star project and observed with the Research and Education Collaborative Occultation Network (RECON) on 2018-October-20-UT. A single detection and a nearby nondetection provide constraints for the size and albedo. When a circular profile is assumed, the radius is r=110_-10_^+14^km, corresponding to a geometric albedo p_V_=0.21_-0.05_^+0.03^, for an adopted absolute magnitude of HV=5.6, typical of other objects in dynamically similar orbits. The occultation also provides a high-precision astrometric constraint.
- ID:
- ivo://CDS.VizieR/J/AJ/103/983
- Title:
- Stellar occultation candidates of Saturn
- Short Name:
- J/AJ/103/983
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 203 potential occultations by Saturn and its rings of stars from the Hubble Space Telescope Guide Star Catalog (GSC), during the years 1991-1999. Because the GSC is not a complete catalog, this is not an exhaustive list of Saturn occultations. In particular, stars brighter than magnitude 8 are not included. However, this list does include many fainter candidates than do current occultation candidate lists for Saturn; these fainter stars also can provide a high signal-to-noise ratio if observed with a large telescope or in the infrared where Saturn and its rings have absorption bands. We list the occultation circumstances, as well as star information found in the GSC.
- ID:
- ivo://CDS.VizieR/J/AJ/156/126
- Title:
- Stellar parameters & abund. from BACCHUS analysis
- Short Name:
- J/AJ/156/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data from the SDSS-IV/Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have been released as part of SDSS Data Releases 13 (DR13) and 14 (DR14). These include high-resolution H-band spectra, radial velocities, and derived stellar parameters and abundances. DR13, released in 2016 August, contained APOGEE data for roughly 150000 stars, and DR14, released in 2017 August, added about 110000 more. Stellar parameters and abundances have been derived with an automated pipeline, the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). We evaluate the performance of this pipeline by comparing the derived stellar parameters and abundances to those inferred from optical spectra and analysis for several hundred stars. For most elements - C, Na, Mg, Al, Si, S, Ca, Cr, Mn, Ni - the DR14 ASPCAP analyses have systematic differences with the comparisons samples of less than 0.05 dex (median), and random differences of less than 0.15 dex (standard deviation). These differences are a combination of the uncertainties in both the comparison samples as well as the ASPCAP analysis. Compared to the references, magnesium is the most accurate alpha-element derived by ASPCAP, and shows a very clear thin/thick disk separation, while nickel is the most accurate iron-peak element (besides iron itself).
- ID:
- ivo://CDS.VizieR/J/A+A/589/A61
- Title:
- Stellar parameters and abundances for M30
- Short Name:
- J/A+A/589/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The prediction of the PLANCK-constrained primordial lithium abundance in the Universe is in discordance with the observed Li abundances in warm Population II dwarf and subgiant stars. Among the physically best motivated ideas, it has been suggested that this discrepancy can be alleviated if the stars observed today had undergone photospheric depletion of lithium. The cause of this depletion is investigated by accurately tracing the behaviour of the lithium abundances as a function of effective temperature. Globular clusters are ideal laboratories for such an abundance analysis as the relative stellar parameters of their stars can be precisely determined. We performed a homogeneous chemical abundance analysis of 144 stars in the metal-poor globular cluster M30, ranging from the cluster turnoff point to the tip of the red giant branch. Non-local thermal equilibrium (NLTE) abundances for Li, Ca, and Fe were derived where possible by fitting spectra obtained with VLT/FLAMES-GIRAFFE using the quantitative-spectroscopy package SME. Stellar parameters were derived by matching isochrones to the observed V vs V-I colour-magnitude diagram. Independent effective temperatures were obtained from automated profile fitting of the Balmer lines and by applying colour-Teff calibrations to the broadband photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A72
- Title:
- Stellar parameters and abundances in NGC 6752
- Short Name:
- J/A+A/567/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abundance trends in heavier elements with evolutionary phase have been shown to exist in the globular cluster NGC 6752. These trends are a result of atomic diffusion and additional (non-convective) mixing. Studying such trends can provide us with important constraints on the extent to which diffusion modifies the internal structure and surface abundances of solar-type, metal-poor stars. Taking advantage of a larger data sample, we investigate the reality and the size of these abundance trends and address questions and potential biases associated with the various stellar populations that make up NGC 6752. We perform an abundance analysis by combining photometric and spectroscopic data of 194 stars located between the turnoff point and the base of the red giant branch. Stellar parameters are derived from uvby Stromgren photometry. Using the quantitative-spectroscopy package SME, stellar surface abundances for light elements such as Li, Na, Mg, Al, and Si as well as heavier elements such as Ca, Ti, and Fe are derived in an automated way by fitting synthetic spectra to individual lines in the stellar spectra, obtained with the VLT/FLAMES-GIRAFFE spectrograph. Based on uvby Stromgren photometry, we are able to separate three stellar populations in NGC 6752 along the evolutionary sequence from the base of the red giant branch down to the turnoff point. We find weak systematic abundance trends with evolutionary phase for Ca, Ti, and Fe which are best explained by stellar-structure models including atomic diffusion with efficient additional mixing. We derive a new value for the initial lithium abundance of NGC 6752 after correcting for the effect of atomic diffusion and additional mixing which falls slightly below the predicted standard BBN value. We find three stellar populations by combining photometric and spectroscopic data of 194 stars in the globular cluster NGC 6752. Abundance trends for groups of elements, differently affected by atomic diffusion and additional mixing, are identified. Although the statistical significance of the individual trends is weak, they all support the notion that atomic diffusion is operational along the evolutionary sequence of NGC 6752.
- ID:
- ivo://CDS.VizieR/J/PASJ/63/1035
- Title:
- Stellar parameters and abundances of 99 giants
- Short Name:
- J/PASJ/63/1035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic stellar parameters of 99 late-type G giants based on high-resolution spectra obtained by the High Dispersion Spectrograph attached to Subaru Telescope. These stars are targets of a Doppler survey program searching for extra-solar planets among evolved stars, with a metallicity of -0.8<[Fe/H]<+0.2. We also derived their abundances of 15 chemical elements, including four {alpha}-elements (Mg, Si, Ca, Ti), three odd-Z light elements (Al, K, Sc), four iron peak elements (V, Cr, Fe, Ni), and four neutron-capture elements (Y, Ba, La, Eu). Kinematic properties reveal that most of the program stars belong to the thin disk.
- ID:
- ivo://CDS.VizieR/J/A+A/603/A56
- Title:
- Stellar parameters and assumed wind parameters
- Short Name:
- J/A+A/603/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent observations have challenged our understanding of rotational mixing in massive stars by revealing a population of fast-rotating objects with apparently normal surface nitrogen abundances. However, several questions have arisen because of a number of issues (e.g., presence of numerous upper limits for the nitrogen abundance, unknown multiplicity status, mix of stars with different physical properties such as their mass and evolutionary state that are known to control the amount of rotational mixing), rendering a re-investigation necessary. We have carefully selected a large sample of bright, fast-rotating early-type stars of our Galaxy (40 objects with spectral types between B0.5 and O4). Their high-quality, high-resolution optical spectra were then analysed with the stellar atmosphere modelling codes DETAIL/SURFACE or CMFGEN, depending on the temperature of the target. Several internal and external checks were performed to validate our methods, notably comparing our results with literature data for some well-known objects, studying the effect of gravity darkening, or confronting the results provided by the two codes for stars amenable to both analyses. Furthermore, we have studied the radial velocities of the stars to assess their binarity. This first part of our study presents our methods and provides the derived stellar parameters, He, CNO abundances and the multiplicity status of every star of the sample. It is the first time that He and CNO abundances of such a large number of Galactic massive fast rotators are determined in a homogeneous way.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/435
- Title:
- Stellar parameters and extinction
- Short Name:
- J/MNRAS/411/435
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Astrometric surveys provide the opportunity to measure the absolute magnitudes of large numbers of stars, but only if the individual line-of-sight extinctions are known. Unfortunately, extinction is highly degenerate with stellar effective temperature when estimated from broad band optical/infrared photometry. To address this problem, I introduce a Bayesian method for estimating the intrinsic parameters of a star and its line-of-sight extinction.