- 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.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/344/943
- Title:
- Sh 138 BVRIJHK photometry
- Short Name:
- J/A+A/344/943
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric and spectroscopic study of the compact HII region Sh 138 and its associated stellar cluster. The positions and BVRIJHK magnitudes are obtained for more than 400 stars over a field of about 4' square centred on the HII region. Sh 138 is excited by a cluster of young massive stars. At the cluster's very centre are at least four O-B2 stars separated by less than 4". The brightest of these, both in the visible and the near infrared, exhibits a spectrum similar to those of the more massive Herbig Ae/Be stars. This star, our No. 183, is overluminous by a factor of 2.5 in the visible and four in the near IR with respect to the O9.5V star required to account for the ionization level of the HII region. However star 183's position in the J-H versus H-K diagram does not indicate a near-IR excess. We suggest that this star is a young massive object belonging to a binary or multiple system. The stellar cluster associated with Sh 138 is very reminiscent of the Orion Trapezium cluster: it is centrally peaked around several massive stars, and is dense - more than 550stars/pc^2^ at its centre. The visual extinction in the cluster varies between 5mag and more than 35mag; large variations are observed over very small scales (for example, more than 20mag over less than 4" among the central massive stars).
- 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/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/ApJ/883/88
- Title:
- Short-duration stellar flares from GALEX & Kepler
- Short Name:
- J/ApJ/883/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a population of short-duration near-ultraviolet (NUV) flares in stars observed by the Kepler and Galaxy Evolution Explorer (GALEX) missions. We analyzed the NUV light curves of 34276 stars observed from 2009 to 2013 by both the GALEX (NUV) and Kepler (optical) space missions with the eventual goal of investigating multiwavelength flares. From the GALEX data, we constructed light curves with a 10s cadence, and we ultimately detected 1904 short-duration flares on 1021 stars. The vast majority (94.5%) of these flares have durations less than 5 minutes, with flare flux enhancements above the quiescent flux level ranging from 1.5 to 1700. The flaring stars are primarily solar-like, with Teff ranging from 3000 to 11000K and radii between 0.5 and 15R_{sun}_. This set of flaring stars is almost entirely distinct from that of previous flare surveys of Kepler data and indicates a previously undetected collection of small flares contained within the Kepler sample. The range in flare energies spans 1.8x10^32^-8.9x10^37^erg, with associated relative errors spanning 2%-87%. The flare frequency distribution by energy follows a power law with index {alpha}=1.72+/-0.05, consistent with results of other solar and stellar flare studies at a range of wavelengths. This supports the idea that the NUV flares we observed are governed by the same physical processes present in solar and optical flares. The relationship between flare duration and associated flare energy extends results found for solar and stellar white-light flares, and suggests that these flares originate in regions with magnetic field strengths of several hundred Gauss, and length scales of the order of 10^10^cm.
3297. Short-period Cepheids
- ID:
- ivo://CDS.VizieR/J/AJ/111/902
- Title:
- Short-period Cepheids
- Short Name:
- J/AJ/111/902
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVRI data on 36 short-period (P<5days) Cepheids is given. The observing techniques and reduction procedures are described. A consistent set of finding charts, a set of standard stars for each Cepheid, and improved coordinates are also presented.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/31
- Title:
- Short period spec. & EBs (LPSEB) from LAMOST & PTF
- Short Name:
- J/ApJS/249/31
- Date:
- 10 Dec 2021 16:35:10
- Publisher:
- CDS
- Description:
- Binaries play key roles in determining stellar parameters and exploring stellar evolution models. We build a catalog of 88 eclipsing binaries with spectroscopic information, taking advantage of observations from both the Large Sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) and the Palomar Transient Factory (PTF) surveys. A software pipeline is constructed to identify binary candidates by examining their light curves. The orbital periods of binaries are derived from the Lomb-Scargle method. The key distinguishing features of eclipsing binaries are recognized by a new filter, Flat Test. We classify the eclipsing binaries by applying a Fourier analysis on the light curves. Among all the binary stars, 13 binaries are identified as eclipsing binaries for the first time. The catalog contains the following information: the position, primary eclipsing magnitude and time, eclipsing depth, the number of photometry and radial velocity observations, largest radial velocity difference, binary type, the effective temperature of the observable star Teff, and surface gravity of the observable star logg. The false-positive probability is calculated by using both a Monte Carlo simulation and real data from the Sloan Digital Sky Survey Stripe 82 Standard Catalog. The binaries in the catalog are mostly with a period of less than one day. The period distribution shows a 0.22 day cutoff, which is consistent with the low probability of an eclipsing binary rotating with such a period.
- ID:
- ivo://CDS.VizieR/J/AJ/158/68
- Title:
- Short-period variables in young open cluster Stock 8
- Short Name:
- J/AJ/158/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present time-series photometry in the field of Stock 8 and identified 130 short-period variable stars. Twenty-eight main-sequence and 23 pre-main-sequence variables are found to be part of cluster Stock 8. The main-sequence variables are classified as slow pulsators of the B-type, {beta} Cep, and {delta} Scuti stars. Fourteen main-sequence stars could be new class variables as discussed by Mowlavi et al. (2013, J/A+A/554/A108) and Lata et al. (2011MNRAS.418.1346L; 2012MNRAS.427.1449L; 2014, J/MNRAS/442/273; 2016MNRAS.456.2505L). The age and mass of pre-main-sequence variables are found to be ~<5 Myr and in the mass range of 0.5-2.8 M_{sun}_, respectively. These pre-main-sequence stars could be T-Tauri variables. We have found 5 and 2 of 23 pre-main-sequence variables as classical T-Tauri stars and Herbig Ae/Be stars, respectively, whereas 16 pre-main-sequence stars are classified as weak-line T-Tauri stars.
- ID:
- ivo://CDS.VizieR/J/A+A/467/73
- Title:
- 3{sigma} hard sample of XMDS survey
- Short Name:
- J/A+A/467/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our goal is to probe the populations of obscured and unobscured AGN investigating their optical-IR and X-ray properties as a function of X-ray flux, luminosity and redshift within a hard X-ray selected sample with wide multiwavelength coverage. We selected a sample of 136 X-ray sources detected at a significance of >=3{sigma} in the 2-10keV band (F_2-10_>~10^-14^erg/cm^2^/s) in a ~1deg^2^ area in the XMM Medium Deep Survey (XMDS, Cat. <J/A+A/439/413>). The XMDS area is covered with optical photometry from the VVDS and CFHTLS surveys and infrared Spitzer data from the SWIRE survey. Based on the X-ray luminosity and X-ray to optical ratio, 132 sources are likely AGN, of which 122 have unambiguous optical - IR identification. The observed optical and IR spectral energy distributions of all identified sources are fitted with AGN/galaxy templates in order to classify them and compute photometric redshifts. X-ray spectral analysis is performed individually for sources with a sufficient number of counts and using a stacking technique for subsamples of sources at different flux levels. Hardness ratios are used to estimate X-ray absorption in individual weak sources.
