- ID:
- ivo://CDS.VizieR/J/MNRAS/427/2647
- Title:
- Sgr dSph stars spectral classification
- Short Name:
- J/MNRAS/427/2647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 1142 colour-selected stars in the direction of the Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy, of which 1058 were taken with VLT/FLAMES multi-object spectrograph and 84 were taken with the SAAO Radcliffe 1.9-m telescope grating spectrograph. Spectroscopic membership is confirmed (at >99 per cent confidence) for 592 stars on the basis of their radial velocity, and spectral types are given. Very slow rotation is marginally detected around the galaxy's major axis. We identify five S stars and 23 carbon stars, of which all but four carbon stars are newly determined and all but one (PQ Sgr) are likely Sgr dSph members. We examine the onset of carbon richness in this metal-poor galaxy in the context of stellar models. We compare the stellar death rate (one star per 1000-1700yr) with the known planetary nebula dynamical ages and find that the bulk population produce the observed (carbon-rich) planetary nebulae. We compute average lifetimes of S and carbon stars as 60-250 and 130-500kyr, compared to a total thermal-pulsing asymptotic giant branch lifetime of 530-1330kyr. We conclude by discussing the return of carbon-rich material to the interstellar medium.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/513/A62
- Title:
- Sgr dSph VIMOS photometry and radial velocities
- Short Name:
- J/A+A/513/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sagittarius dwarf Spheroidal Galaxy (Sgr dSph) provides us with a unique possibility of studying a dwarf galaxy merging event while still in progress. Moving along a short-period, quasi-polar orbit in the Milky Way Halo, Sgr dSph is being tidally dispersed along a huge stellar stream. Due to its low distance (25kpc), the main body of Sgr dSph covers a vast area in the sky (roughly 15x7degrees). Available photometric and spectroscopic studies have concentrated either on the central part of the galaxy or on the stellar stream, but the overwhelming majority of the galaxy body has never been probed. The aim of the present study is twofold. On the one hand, to produce color magnitude diagrams across the extension of Sgr dSph to study its stellar populations, searching for age and/or composition gradients (or lack thereof). On the other hand, to derive spectroscopic low-resolution radial velocities for a subsample of stars to determine membership to Sgr dSph for the purpose of high resolution spectroscopic follow-up.
- ID:
- ivo://CDS.VizieR/VII/196
- Title:
- Shakhbazian compact groups of galaxies
- Short Name:
- VII/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest survey of compact galaxy groups was published by Shakhbazian et al. (see cat. <VII/89>). This catalogue provides accurate positions of individual galaxies in the groups; photometrical properties of the Southern sky (delta not greater than +2{deg}30') are evaluated on the basis of the COSMOS/UKST catalog of the Southern sky. The catalogue contains 373 groups; this number differs from the number in Shakhbazian's list (377 groups) by the following: => No data for groups 001 (there were already published data by other authors), 206 (could not be re-identified) 241 (could not be re-identified) 252 (is identical with 214), 301 (could not be re-identified) 353 (could not be re-identified) => Group 328 was published twice (in North and South) => Group 340 was divided in two parts (340 and 340a), according to Bettoni and Fasano ([BF95]=1995AJ....109...32B)
- ID:
- ivo://CDS.VizieR/J/A+A/585/A84
- Title:
- Shape parameters of lensing galaxies
- Short Name:
- J/A+A/585/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as like GALFIT or IMFITFITS and various PSF-determining methods have resulted in somewhat discrepant results. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. The morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. Methods. We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half- light radius of the galaxy. Our half-light radius measurement method is based on an innovative scheme for computing isophotes that is well suited to measuring the morphological properties of gravitational lensing galaxies. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested against GALFIT. It is then applied to a sample of systems from the CASTLES database.
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1490
- Title:
- Shapes of BCGs in nearby clusters shapes
- Short Name:
- J/MNRAS/404/1490
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the apparent axial ratio distributions of the brightest cluster galaxies (BCGs) and normal ellipticals (Es) in our sample of 75 galaxy clusters from the WIde-field Nearby Galaxy-cluster Survey (WINGS). Most BCGs in our clusters (69 per cent) are classified as cD galaxies. The sample of cDs has been completed by 14 additional cDs (non-BCGs) we found in our clusters. We deproject the apparent axial ratio distributions of Es, BCGs and cDs using a bivariate version of the Lucy rectification algorithm, whose results are supported by an independent Monte Carlo technique. Finally, we compare the intrinsic shape distribution of BCGs to the corresponding shape distribution of the central part of cluster-sized dark matter haloes extracted from the GIF2 Lambda cold dark matter ({LAMBDA}CDM) N-body simulations (Gao et al., 2004MNRAS.355..819G).
- ID:
- ivo://CDS.VizieR/J/A+AS/114/21
- Title:
- Shapley-Ames Galaxies at 2.8cm
- Short Name:
- J/A+AS/114/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the radio continuum emission at 2.8 cm of a nearly complete sample of spiral galaxies. The sample consists of the Shapley-Ames galaxies north of {delta}=-25deg and brighter than B_T_=+12. The large, nearby galaxies were not observed during the survey, but measured with high sensitivity in individual projects. The radioweak galaxies were also excluded. The observational results and the derived flux densities are given and compared with that of other observations. Pecularities of the radio emission of individual galaxies are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/762/46
- Title:
- SHARDS: GOODS-N spectrophotometry survey
- Short Name:
- J/ApJ/762/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130arcmin2 at wavelengths between 500 and 950nm with 24 contiguous medium-band filters (providing a spectral resolution R~50). The data reach an AB magnitude of 26.5 (at least at a 3{sigma} level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z>1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z=0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0<z<~1.4.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A119
- Title:
- SHARDS S0 and E/S0 with anti-truncated disc
- Short Name:
- J/A+A/604/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The controversy about the origin of the structure of early-type S0-E/S0 galaxies may be due to the difficulty of comparing surface brightness profiles with different depths, photometric corrections and point spread function (PSF) effects (which are almost always ignored). We aim to quantify the properties of Type-III (anti-truncated) discs in a sample of S0 galaxies at 0.2<z<0.6. In this paper, we present the sample selection and describe in detail the methods to robustly trace the structure in their outskirts and correct for PSF effects. We have selected and classified a sample of 150 quiescent galaxies at 0.2<z<0.6 in the GOODS-N field. We performed a quantitative structural analysis of 44 S0-E/S0 galaxies. We have corrected their surface brightness profiles for PSF distortions and analysed the biases in the structural and photometric parameters when the PSF correction is not applied. Additionally, we have developed Elbow, an automatic statistical method to determine whether a possible break is significant - or not - and its type. We have made this method publicly available. We find 14 anti-truncated S0-E/S0 galaxies in the range 0.2<z<0.6 (~30% of the final sample). This fraction is similar to the those reported in the local Universe. In our sample, ~25% of the Type-III breaks observed in PSF-uncorrected profiles are artifacts, and their profiles turn into a Type I after PSF correction. PSF effects also soften Type-II profiles. We find that the profiles of Type-I S0 and E/S0 galaxies of our sample are compatible with the inner profiles of the Type-III, in contrast with the outer profiles. We have obtained the first robust and reliable sample of 14 anti-truncated S0-E/S0 galaxies beyond the local Universe, in the range 0.2<z<0.6. PSF effects significantly affect the shape of the surface brightness profiles in galaxy discs even in the case of the narrow PSF of HST/ACS images, so future studies on the subject should make an effort to correct them.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/35
- Title:
- SHELS: complete galaxy redshift survey for R<=20.6
- Short Name:
- J/ApJS/213/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey to a limiting R=20.6. Here we describe the redshift survey of the F2 field (RA_J2000_=09h19m32.4s and DE_J2000_=+30{deg}00'00"). The survey includes 16294 new redshifts measured with the Hectospec on the MMT. The resulting survey of the 4deg^2^ F2 field is 95% complete to R=20.6, currently the densest survey to this magnitude limit. The median survey redshift is z=0.3; the survey provides a view of structure in the range 0.1<~z<~0.6. An animation displays the large-scale structure in the survey region. We provide a redshift, spectral index D_n_4000, and stellar mass for each galaxy in the survey. We also provide a metallicity for each galaxy in the range 0.2<z<0.38. To demonstrate potential applications of the survey, we examine the behavior of the index D_n_4000 as a function of galaxy luminosity, stellar mass, and redshift. The known evolutionary and stellar mass dependent properties of the galaxy population are cleanly evident in the data. We also show that the mass-metallicity relation previously determined from these data is robust to the analysis approach.
- ID:
- ivo://CDS.VizieR/J/AJ/143/102
- Title:
- SHELS galaxies with 0.02<z<0.1
- Short Name:
- J/AJ/143/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Smithsonian Hectospec Lensing Survey (SHELS) is a dense redshift survey covering a 4deg^2^ region to a limiting R=20.6. In the construction of the galaxy catalog and in the acquisition of spectroscopic targets, we paid careful attention to the survey completeness for lower surface brightness dwarf galaxies. Thus, although the survey covers a small area, it is a robust basis for computation of the slope of the faint end of the galaxy luminosity function to a limiting M_R_=-13.3+5logh. We calculate the faint-end slope in the R band for the subset of SHELS galaxies with redshifts in the range 0.02<=z<0.1, SHELS_0.1_. This sample contains 532 galaxies with R<20.6 and with a median surface brightness within the half-light radius of SB_50,R_=21.82mag/arcsec^2^. We used this sample to make one of the few direct measurements of the dependence of the faint end of the galaxy luminosity function on surface brightness. For the sample as a whole the faint-end slope, {alpha}=-1.31+/-0.04, is consistent with both the Blanton et al. analysis of the Sloan Digital Sky Survey (2005ApJ...631..208B, 2005AJ....129.2562B) and the Liu et al. analysis of the COSMOS field (2008ApJ...672..198L). This consistency is impressive given the very different approaches of these three surveys. A magnitude-limited sample of 135 galaxies with optical spectroscopic redshifts with mean half-light surface brightness, SB_50,R_>=22.5mag/arcsec^2^ is unique to SHELS_0.1_. The faint-end slope is {alpha}_22.5_=-1.52+/-0.16. SHELS_0.1_ shows that lower surface brightness objects dominate the faint-end slope of the luminosity function in the field, underscoring the importance of surface brightness limits in evaluating measurements of the faint-end slope and its evolution.