- 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/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.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/91
- Title:
- SHELS galaxy sizes using Subaru/HSC imaging
- Short Name:
- J/ApJ/872/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the relationships between size, stellar mass, and average stellar population age (indicated by D_n_4000 indices) for a sample of ~11000 intermediate-redshift galaxies from the SHELS spectroscopic survey (Geller+ 2014, J/ApJS/213/35) augmented by high-resolution Subaru Telescope Hyper Suprime-Cam imaging. In the redshift interval 0.1<z<0.6, star-forming galaxies are on average larger than their quiescent counterparts. The mass-complete sample of ~3500M_*_>10^10^M_{sun}_ quiescent galaxies shows that the average size of a 10^11^M_{sun}_ quiescent galaxy increases by <~25% from z~0.6 to z~0.1. This growth rate is a function of stellar mass: the most massive (M_*_>10^10^M_{sun}_) galaxies grow significantly more slowly in size than quiescent systems an order of magnitude less massive that grow by 70% in the 0.1<~z<~0.3 redshift interval. For M_*_<10^11^M_{sun}_ galaxies, age and size are anticorrelated at fixed mass; more massive quiescent systems show no significant trend in size with average stellar population age. The evolution in absolute and fractional abundances of quiescent systems at intermediate redshift are also a function of galaxy stellar mass. The suite of evolutionary trends suggests that galaxies more massive than ~10^11^M_{sun}_ have mostly assembled their mass by z~0.6. Quiescent galaxies with lower stellar masses show more complex evolution that is characterized by a combination of individual quiescent galaxy size growth (through mergers) and an increase in the size of newly quenched galaxies joining the population at later times (progenitor bias). The low-mass population (M_*_~10^10^M_{sun}_) grows predominantly as a result of progenitor bias. For more massive (M_*_~5x10^10^M_{sun}_) quiescent galaxies, (predominantly minor) mergers and progenitor bias make more comparable contributions to the size growth. At intermediate redshift, quiescent size growth is mass-dependent; the most massive (M_*_>10^10^M_{sun}_) galaxies experience the least rapid increase in size from z~0.6 to z~0.1.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/11
- Title:
- SHELS: redshift survey of the F1 DLS field
- Short Name:
- J/ApJS/224/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Smithsonian Hectospec Lensing Survey (SHELS) is a complete redshift survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey (DLS). Both fields are more than 94% complete to a Galactic extinction corrected R_0_=20.2. Here, we describe the redshift survey of the F1 field centered at RA=00:53:25.3 and DEC=12:33:55 (J2000); like F2, the F1 field covers ~4deg^2^. The redshift survey of the F1 field includes 9426 new galaxy redshifts measured with Hectospec on the MMT (published here). As a guide to future uses of the combined survey, we compare the mass metallicity relation and the distributions of D_n_4000 as a function of stellar mass and redshift for the two fields. The mass-metallicity relations differ by an insignificant 1.6{sigma}. For galaxies in the stellar mass range 10^10^-10^11^M_{sun}_, the increase in the star-forming fraction with redshift is remarkably similar in the two fields. The seemingly surprising 31%-38% difference in the overall galaxy counts in F1 and F2 is probably consistent with the expected cosmic variance given the subtleties of the relative systematics in the two surveys. We also review the DLS cluster detections in the two fields: poorer photometric data for F1 precluded secure detection of the single massive cluster at z=0.35 that we find in SHELS. Taken together, the two fields include 16055 redshifts for galaxies with R_0_<=20.2 and 20754 redshifts for galaxies with R<=20.6. These dense surveys in two well-separated fields provide a basis for future investigations of galaxy properties and large-scale structure.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A6
- Title:
- sigma Gem BV photometry
- Short Name:
- J/A+A/646/A6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to study the spot evolution and differential rotation in the magnetically active cool K-type giant star sigma Gem from broadband photometry and continuous spectroscopic observations that span 150 nights. We use high-resolution, high signal-to-noise ratio spectra obtained with the Hertzsprung SONG telescope to reconstruct surface (photospheric) temperature maps with Doppler imaging techniques. The 303 observations span 150 nights and allow for a detailed analysis of the spot evolution and surface differential rotation. The Doppler imaging results are compared to simultaneous broadband photometry from the Tennessee State University T3 0.4m Automated Photometric Telescope. The activity from the stellar chromosphere, which is higher in the stellar atmosphere, is also studied using SONG observations of Balmer Halpha line profiles and correlated with the photospheric activity. The temperature maps obtained during eight consecutive stellar rotations show mainly high-latitude or polar spots, with the main spot concentrations above latitude 45{deg}. The spots concentrate around phase 0.25 near the beginning of our observations and around phase 0.75 towards the end. The photometric observations confirm a small jump in spot phases that occurred in February 2016. The cross-correlation of the temperature maps reveals rather strong solar-like differential rotation, giving a relative surface differential rotation coefficient of alpha=0.10+/-0.02. There is a weak correlation between the locations of starspots and enhanced emission in the chromosphere at some epochs.
- ID:
- ivo://CDS.VizieR/J/ApJ/706/1364
- Title:
- SINS survey of high-redshift galaxies
- Short Name:
- J/ApJ/706/1364
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Spectroscopic Imaging survey in the near-infrared (near-IR) with SINFONI (SINS) of high-redshift galaxies. With 80 objects observed and 63 detected in at least one rest-frame optical nebular emission line, mainly H{alpha}, SINS represents the largest survey of spatially resolved gas kinematics, morphologies, and physical properties of star-forming galaxies at z~1-3. We describe the selection of the targets, the observations, and the data reduction. We then focus on the "SINS H{alpha} sample," consisting of 62 rest-UV/optically selected sources at 1.3<z<2.6 for which we targeted primarily the H{alpha} and [NII] emission lines. Only ~30% of this sample had previous near-IR spectroscopic observations. The galaxies were drawn from various imaging surveys with different photometric criteria; as a whole, the SINS H{alpha} sample covers a reasonable representation of massive M_*_>~10^10^M_{sun}_ star-forming galaxies at z~1.5-2.5, with some bias toward bluer systems compared to pure K-selected samples due to the requirement of secure optical redshift. The H{alpha} morphologies tend to be irregular and/or clumpy. About one-third of the SINS H{alpha} sample galaxies are rotation-dominated yet turbulent disks, another one-third comprises compact and velocity dispersion-dominated objects, and the remaining galaxies are clear interacting/merging systems; the fraction of rotation-dominated systems increases among the more massive part of the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/851/48
- Title:
- SLACS. XIII. Galaxy-scale strong lens candidates
- Short Name:
- J/ApJ/851/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the full sample of 118 galaxy-scale strong-lens candidates in the Sloan Lens ACS (SLACS) Survey for the Masses (S4TM) Survey, which are spectroscopically selected from the final data release of the Sloan Digital Sky Survey. Follow-up Hubble Space Telescope (HST) imaging observations confirm that 40 candidates are definite strong lenses with multiple lensed images. The foreground-lens galaxies are found to be early-type galaxies (ETGs) at redshifts 0.06-0.44, and background sources are emission-line galaxies at redshifts 0.22-1.29. As an extension of the SLACS Survey, the S4TM Survey is the first attempt to preferentially search for strong-lens systems with relatively lower lens masses than those in the pre-existing strong-lens samples. By fitting HST data with a singular isothermal ellipsoid model, we find that the total projected mass within the Einstein radius of the S4TM strong-lens sample ranges from 3x10^10^M_{sun}_ to 2x10^11^M_{sun}_. In Shu+ (2015ApJ...803...71S), we have derived the total stellar mass of the S4TM lenses to be 5x10^10^M_{sun}_ to 1x10^12^M_{sun}_. Both the total enclosed mass and stellar mass of the S4TM lenses are on average almost a factor of 2 smaller than those of the SLACS lenses, which also represent the typical mass scales of the current strong-lens samples. The extended mass coverage provided by the S4TM sample can enable a direct test, with the aid of strong lensing, for transitions in scaling relations, kinematic properties, mass structure, and dark-matter content trends of ETGs at intermediate-mass scales as noted in previous studies.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A90
- Title:
- SN 2020cxd multi-photometry
- Short Name:
- J/A+A/655/A90
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present observations and analysis of SN 2020cxd, a low-luminosity (LL), long-lived Type IIP supernova (SN). This object was a clear outlier in the magnitude-limited SN sample recently presented by the Zwicky Transient Facility (ZTF) Bright Transient Survey. We demonstrate that SN 2020cxd is an additional member of the group of LL SNe, and discuss the rarity of LL SNe in the context of the ZTF survey, and how further studies of these faintest members of the core-collapse (CC) SN family might help understand the underlying initial mass function for stars that explode. We present optical light curves (LCs) from the ZTF in the $gri$ bands and several epochs of ultra-violet data from the Neil Gehrels Swift Observatory as well as a sequence of optical spectra. We construct colour curves, a bolometric LC, compare ejecta-velocity and black-body temperature evolutions for LL SNe, as well as for typical Type II SNe. Furthermore, we adopt a Monte Carlo code that fits semi-analytic models to the LC of SN 2020cxd, which allows the estimation of physical parameters. Using our late-time nebular spectra, we also compare against SN II spectral synthesis models from the literature to constrain the progenitor properties of SN 2020cxd. The LCs of SN 2020cxd show great similarity with those of LL SNe IIP, in luminosity, timescale and colours. Also the spectral evolution of SN 2020cxd is that of a Type IIP SN. The spectra show prominent and narrow P-Cygni lines, indicating low expansion velocities. This is one of the faintest LL SNe observed, with an absolute plateau magnitude of M_r_=-14.5mag, and also one with the longest plateau lengths, with a duration of 118 days. Finally, the velocities measured from the nebular emission lines are among the lowest ever seen in a SN, with intrinsic Full Width at Half Maximum of 478km/s. The underluminous late-time exponential LC tail indicates that the mass of ^56^Ni ejected during the explosion is much smaller than the average of normal SNe IIP, we estimate M_^56^Ni_=0.003M+{sun+_. The Monte Carlo fitting of the bolometric LC suggests that the progenitor of SN 2020cxd had a radius of R_0_=1.3x10^13^cm, kinetic energy of E_kin_=4.3x10^50^erg, and ejecta mass M_ej_=9.5M_{sun}_. From the bolometric LC, we estimate the total radiated energy E_rad_=1.52x10^48^erg. Using our late-time nebular spectra, we compare against SN II spectral synthesis models to constrain the progenitor Zero-age Main-sequence mass and found it likely to be <~15M_{sun}+. SN 2020cxd is a LL Type IIP SN. The inferred progenitor parameters and the features observed in the nebular spectrum favour a low-energy, Ni-poor, iron CC SN from a low mass ~12M_{sun}_ red supergiant.
- ID:
- ivo://CDS.VizieR/J/ApJS/233/6
- Title:
- SNe II light curves & spectra from the CfA
- Short Name:
- J/ApJS/233/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multiband photometry of 60 spectroscopically confirmed supernovae (SNe): 39 SNe II/IIP, 19 IIn, 1 IIb, and 1 that was originally classified as a IIn but later as a Ibn. Of these, 46 have only optical photometry, 6 have only near-infrared (NIR) photometry, and 8 have both optical and NIR. The median redshift of the sample is 0.016. We also present 195 optical spectra for 48 of the 60 SN. There are 26 optical and 2 NIR light curves of SNe II/IIP with redshifts z>0.01, some of which may give rise to useful distances for cosmological applications. All photometry was obtained between 2000 and 2011 at the Fred Lawrence Whipple Observatory (FLWO), via the 1.2m and 1.3m PAIRITEL telescopes for the optical and NIR, respectively. Each SN was observed in a subset of the u'UBVRIr'i'JHK_s_ bands. There are a total of 2932 optical and 816 NIR light curve points. Optical spectra were obtained using the FLWO 1.5m Tillinghast telescope with the FAST spectrograph and the MMT Telescope with the Blue Channel Spectrograph. Our photometry is in reasonable agreement with select samples from the literature: two-thirds of our star sequences have average V offsets within +/-0.02mag and roughly three-quarters of our light curves have average differences within +/-0.04mag. The data from this work and the literature will provide insight into SN II explosions, help with developing methods for photometric SN classification, and contribute to their use as cosmological distance indicators.