- ID:
- ivo://CDS.VizieR/J/A+A/524/A6
- Title:
- Evolution of spectral early-type galaxies
- Short Name:
- J/A+A/524/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the evolution of spectral early-type galaxies in clusters, groups, and the field up to redshift 0.9 using the ESO Distant Cluster Survey (EDisCS) dataset. We measure structural parameters (circularized half-luminosity radii Re, surface brightness Ie, and velocity dispersions sigma) for 154 cluster and 68 field galaxies. On average, we achieve precisions of 10% in Re, 0.1dex in logIe, and 10% in sigma. We sample ~20% of cluster and ~10% of field spectral early-type galaxies to an I band magnitude in a 1arcsec radius aperture as faint as I1=22. We study the evolution of the zero point of the fundamental plane (FP) and confirm results in the literature, but now also for the low cluster velocity dispersion regime.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/572/L5
- Title:
- Evolution state of red giants from seismology
- Short Name:
- J/A+A/572/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection of oscillations with a mixed character in subgiants and red giants allows us to probe the physical conditions in their cores. With these mixed modes, we aim at determining seismic markers of stellar evolution. Kepler asteroseismic data were selected to map various evolutionary stages and stellar masses. Seismic evolutionary tracks were then drawn with the combination of the frequency and period spacings.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A33
- Title:
- EX Lup SPHERE and SINFONI images
- Short Name:
- J/A+A/641/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- EX Lup is a well-studied T Tauri star that represents the prototype of young eruptive stars EXors. These are characterized by repetitive outbursts due to enhanced accretion from the circumstellar disk onto the star. In this paper we analyze new adaptive optics imaging and spectroscopic observations to study EX Lup and its circumstellar environment in near-infrared in its quiescent phase. We aim at providing a comprehensive understanding of the circumstellar environment around EX Lup in quiescence that builds upon the vast literature data. We observed EX Lup in quiescence with the high contrast imager SPHERE/IRDIS in the dual-beam polarimetric imaging mode to resolve the circumstellar environment in near-infrared scattered light. We complemented these data with earlier SINFONI spectroscopy, also taken in quiescence. Results.We resolve for the first time in scattered light a compact feature around EX Lup azimuthally extending from ~280{deg} to ~360{deg}, and radially extending from 0.3" to 0.55" in the plane of the disk. We explore two different scenarios for the detected emission. The first one accounts for the emission as coming from the brightened walls of the cavity excavated by the outflow whose presence was suggested by ALMA observations in the J=3-2 line of ^12^CO. The second one accounts for the emission as coming from an inclined disk. In this latter case we detect for the first time a more extended circumstellar disk in scattered light, which shows that a region between 10 and 30au is depleted of um-size grains. We compare the J-, H- and K- band spectra obtained with SINFONI in quiescence with the spectra taken during the outburst, showing that all the emission lines were due to the episodic accretion event. Based on the morphology analysis we favour the scenario in which the scattered light is coming from a circumstellar disk rather than the outflow around EX Lup. We analyze the origin of the observed feature either as coming from a continuous circumstellar disk with a cavity, or from the illuminated wall of the outer disk or from a shadowed disk. Moreover, we discuss what is the origin of the m-size grains depleted region, exploring the possibility that a sub-stellar companion may be the cause of it.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A11
- Title:
- Exocomets. A Spectroscopic Survey
- Short Name:
- J/A+A/639/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events, which are interpreted to be exocomets (falling evaporating bodies) around beta Pic in the early 1980s, Monly 20 stars have been reported to host exocomet-like events. We aim to expand the sample of known exocomet-host stars, as well as to monitor the hot-gas environment around stars with previously known exocometary activity. We have obtained high-resolution optical spectra of a heterogeneous sample of 117 main-sequence stars in the spectral type range from B8 to G8. The data were collected in 14 observing campaigns over the course of two years from both hemispheres. We analysed the CaII K&H and NaI D lines in order to search for non-photospheric absorptions that originated in the circumstellar environment and for variable events that could be caused by the outgassing of exocomet-like bodies. We detected non-photospheric absorptions towards 50% of the sample, thus attributing a circumstellar origin to half of the detections (i.e. 26% of the sample). Hot circumstellar gas was detected in the metallic lines inspected via narrow stable absorptions and/or variable blue- and red-shifted absorption events. Such variable events were found in 18 stars in the CaII and/or NaI lines; six of them are reported in the context of this work for the first time. In some cases, the variations we report in the CaII K line are similar to those observed in beta^L Pic. While we do not find a significant trend in the age or location of the stars, we do find that the probability of finding CS gas in stars with larger vsini is higher. We also find a weak trend with the presence of near-infrared excess and with anomalous (lambda Boo-like) abundances, but this would require confirmation by expanding the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/11
- Title:
- Exploring 6 AGN dusty torus models. II.
- Short Name:
- J/ApJ/884/11
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers devoted to exploring a set of six dusty models of active galactic nuclei (AGN) with available spectral energy distributions. These models are the smooth torus by Fritz+ (2006MNRAS.366..767F), the clumpy torus by Nenkova+ (2008ApJ...685..147N and 2008ApJ...685..160N), the clumpy torus by Honig & Kishimoto (2010A&A...523A..27H), the two-phase torus by Siebenmorgen+ (2015A&A...583A.120S), the two-phase torus by Stalevski+ (2012MNRAS.420.2756S and 2016MNRAS.458.2288S), and the wind model by Honig & Kishimoto (2017ApJ...838L..20H). The first paper explores discrimination among models and the parameter restriction using synthetic spectra. Here we perform spectral fitting of a sample of 110 AGN drawn from the Swift/BAT survey with Spitzer/IRS spectroscopic data. The aim is to explore which is the model that describes better the data and the resulting parameters. The clumpy wind-disk model by Honig & Kishimoto provides good fits for ~50% of the sample, and the clumpy torus model by Nenkova+ is good at describing ~30% of the objects. The wind-disk model by Honig & Kishimoto is better for reproducing the mid-infrared spectra of type 1 Seyferts (with 60% of the type 1 Seyferts well reproduced by this model compared to the 10% well represented by the clumpy torus model by Nenkova+), while type 2 Seyferts are equally fitted by both models (roughly 40% of the type 2 Seyferts). Large residuals are found irrespective of the model used, indicating that the AGN dust continuum emission is more complex than predicted by the models or that the parameter space is not well sampled. We found that all the resulting parameters for our AGN sample are roughly constrained to 10%-20% of the parameter space. Contrary to what is generally assumed, the derived outer radius of the torus is smaller (reaching up to a factor of ~5 smaller for 10pc tori) for the smooth torus by Fritz+ and the two-phase torus by Stalevski+ than the one derived from the clumpy torus by Nenkova+ Covering factors and line-of-sight viewing angles strongly depend on the model used. The total dust mass is the most robust derived quantity, giving equivalent results for four of these models.
- ID:
- ivo://CDS.VizieR/J/ApJS/228/19
- Title:
- Exploring the SDSS data set. I. EMP & CV stars
- Short Name:
- J/ApJS/228/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for extremely metal-poor (EMP), carbon-enhanced metal-poor (CEMP), and cataclysmic variable (CV) stars using a new exploration tool based on linked scatter plots (LSPs). Our approach is especially designed to work with very large spectrum data sets such as the SDSS, LAMOST, RAVE, and Gaia data sets, and it can be applied to stellar, galaxy, and quasar spectra. As a demonstration, we conduct our search using the SDSS DR10 data set. We first created a 3326-dimensional phase space containing nearly 2 billion measures of the strengths of over 1600 spectral features in 569738 SDSS stars. These measures capture essentially all the stellar atomic and molecular species visible at the resolution of SDSS spectra. We show how LSPs can be used to quickly isolate and examine interesting portions of this phase space. To illustrate, we use LSPs coupled with cuts in selected portions of phase space to extract EMP stars, CEMP stars, and CV stars. We present identifications for 59 previously unrecognized candidate EMP stars and 11 previously unrecognized candidate CEMP stars. We also call attention to 2 candidate He II emission CV stars found by the LSP approach that have not yet been discussed in the literature.
- ID:
- ivo://CDS.VizieR/J/ApJS/225/32
- Title:
- Extended abundance analysis of cool stars
- Short Name:
- J/ApJS/225/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of uniformly determined stellar properties and abundances for 1615 F, G, and K stars using an automated spectral synthesis modeling procedure. All stars were observed using the HIRES spectrograph at Keck Observatory. Our procedure used a single line list to fit model spectra to observations of all stars to determine effective temperature, surface gravity, metallicity, projected rotational velocity, and the abundances of 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Sixty percent of the sample had Hipparcos parallaxes and V-band photometry, which we combined with the spectroscopic results to obtain mass, radius, and luminosity. Additionally, we used the luminosity, effective temperature, metallicity and {alpha}-element enhancement to interpolate in the Yonsei-Yale isochrones to derive mass, radius, gravity, and age ranges for those stars. Finally, we determined new relations between effective temperature and macroturbulence for dwarfs and subgiants. Our analysis achieved precisions of 25K in T_eff_, 0.01dex in [M/H], 0.028dex for logg, and 0.5km/s in vsini based on multiple observations of the same stars. The abundance results were similarly precise, between ~0.01 and ~0.04dex, though trends with respect to T_eff_ remained for which we derived empirical corrections. The trends, though small, were much larger than our uncertainties and are shared with published abundances. We show that changing our model atmosphere grid accounts for most of the trend in [M/H] between 5000 and 5500K, indicating a possible problem with the atmosphere models or opacities.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/38
- Title:
- Extended abundance analysis of KOIs
- Short Name:
- J/ApJS/237/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate stellar parameters and precise elemental abundances are vital pieces to correctly characterize discovered planetary systems, better understand planet formation, and trace galactic chemical evolution. We have performed a uniform spectroscopic analysis for 1127 stars, yielding accurate gravity, temperature, and projected rotational velocity in addition to precise abundances for 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Most of the stars in this sample are Kepler Objects of Interest, observed by the California-Kepler Survey, and include 1003 stars hosting 1562 confirmed planets. This catalog extends the uniform analysis of our previous catalog, bringing the total number of homogeneously analyzed stars to almost 2700 F, G, and K dwarfs. To ensure consistency between the catalogs, we performed an analysis of our ability to recover parameters as a function of signal-to-noise ratio (S/N) and present individual uncertainties as well as functions to calculate uncertainties for parameters derived from lower S/N spectra. With the updated parameters, we used isochrone fitting to derive new radii, masses, and ages for the stars. We use our abundance analysis to support the finding that the radius gap is likely a result of evolution rather than the result of primordial compositional differences between the two populations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/3263
- Title:
- Extended galaxy halo gas through HI and OVI
- Short Name:
- J/MNRAS/449/3263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of extended galaxy halo gas through HI and OVI absorption over two decades in projected distance at z~0.2. The study is based on a sample of 95 galaxies from a highly complete (>80 percent) survey of faint galaxies (L>0.1L*) with archival quasar absorption spectra and 53 galaxies from the literature. A clear anticorrelation is found between HI (OVI) column density and virial radius normalized projected distance, d/Rh. Strong HI (OVI) absorption systems with column densities greater than 10^14.0^ (10^13.5^)cm^-2^ are found for 48 of 54 (36 of 42) galaxies at d<Rh indicating a mean covering fraction of <{kappa}_HI_>=0.89 (<{kappa}_OVI_>=0.86). OVI absorbers are found at d~Rh, beyond the extent observed for lower ionization species. At d/Rh=1-3 strong HI (OVI) absorption systems are found for only 7 of 43 (5 of 34) galaxies (<{kappa}_HI_>=0.16 and <{kappa}_OVI_>=0.15). Beyond d=3Rh, the HI and OVI covering fractions decrease to levels consistent with coincidental systems. The high completeness of the galaxy survey enables an investigation of environmental dependence of extended gas properties. Galaxies with nearby neighbours exhibit a modest increase in Ovi covering fraction at d>Rh compared to isolated galaxies (<{kappa}_OVI_~0.13 versus 0.04) but no excess HI absorption. These findings suggest that environmental effects play a role in distributing heavy elements beyond the enriched gaseous haloes of individual galaxies. Finally, we find that differential HI and OVI absorption between early- and late-type galaxies continues from d<Rh to d~3Rh.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A55
- Title:
- Extrasolar planets. Radial velocities of 5 stars
- Short Name:
- J/A+A/545/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial-velocity measurements obtained in one of a number of programs underway to search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m telescope of the Haute-Provence Observatory. Targets were selected from catalogs observed with ELODIE, which had been mounted previously at the telescope, in order to detect long-period planets with an extended database close to 15 years.
