- ID:
- ivo://CDS.VizieR/J/A+A/629/A131
- Title:
- Reduced X-shooter spectra of GRB 190114A
- Short Name:
- J/A+A/629/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detections of molecular hydrogen (H_2_), vibrationally-excited H_2_ (H_2_*), and neutral atomic carbon (CI), an efficient tracer of molecular gas, in two new afterglow spectra of GRBs 181020A (z=2.938) and 190114A (z=3.376), observed with X-shooter at the Very Large Telescope (VLT). Both host-galaxy absorption systems are characterized by strong damped Lyman-alpha absorbers (DLAs) and substantial amounts of molecular hydrogen with logN(HI,H_2_)=22.20+/-0.05, 20.40+/-0.04 (GRB 181020A) and logN(HI, H_2_)=22.15+/-0.05, 19.44+/-0.04 (GRB 190114A). The DLA metallicites, depletion levels, and dust extinctions are within the typical regimes probed by GRBs with [Zn/H]=-1.57+/-0.06, [Zn/Fe]=0.67+/-0.03, and AV=0.27+/-0.02mag (GRB 181020A) and [Zn/H]=-1.23+/-0.07, [Zn/Fe]=1.06+/-0.08, and AV=0.36+/-0.02mag (GRB 190114A). In addition, we examine the molecular gas content of all known H2-bearing GRB-DLAs and explore the physical conditions and characteristics required to simultaneously probe CI and H_2_*. We confirm that H2 is detected in all CI- and H2*-bearing GRB absorption systems, but that these rarer features are not necessarily detected in all GRB H2 absorbers. We find that a large molecular fraction of f_H2_>~10^-3^ is required for CI to be detected. The defining characteristic for H_2_* to be present is less clear, though a large H_2_ column density is an essential factor. We also find that the observed line profiles of the molecular-gas tracers are kinematically "cold", with small velocity offsets of {delta}v<20km/s from the bulk of the neutral absorbing gas. We then derive the H_2_ excitation temperatures of the molecular gas and find that they are relatively low with Tex~=100-300K, however, there could be evidence of warmer components populating the high-J H_2_ levels in GRBs 181020A and 190114A. Finally, we demonstrate that even though the X-shooter GRB afterglow campaign has been successful in recovering several H2-bearing GRB-host absorbers, this sample is still hampered by a significant dust bias excluding the most dust-obscured H_2_ absorbers from identification. CI and H_2_* could open a potential route to identify molecular gas even in low-metallicity or highly dust-obscured bursts, though they are only efficient tracers for the most H2-rich GRB-host absorption systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/553/A81
- Title:
- Refraction of corundum, spinel, {alpha}-quartz
- Short Name:
- J/A+A/553/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. A high-temperature, high-pressure cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum ({alpha}-Al_2_O_3_), spinel (MgAl_2_O_4_), and {alpha}-quartz (SiO_2_), temperature-dependent optical constants were measured from 300K up to more than 900K. Small particle spectra were also calculated from these data.
- ID:
- ivo://CDS.VizieR/J/A+A/483/661
- Title:
- Refractive index for silicon carbide (SiC)
- Short Name:
- J/A+A/483/661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SiC optical constants are fundamental inputs for radiative transfer (RT) models of astrophysical dust environments. However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic ({beta}) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for {beta}- and {alpha}-SiC derived from single-crystal reflectance spectra and investigate quantitatively (i) whether there is any difference between {alpha}- and {beta}-SiC that can be seen in infrared (IR) spectra and optical functions and (ii) whether weak features from {lambda}~12.5-13.0{mu}m need to be fitted. We measured mid- and far-IR reflectance spectra for two samples of 3C ({beta}-)SiC and four samples of 6H ({alpha}-)SiC. For the latter group, we acquired polarized data (E{perpendicular.to}c, E{parallel.to}c orientations). We calculated the real and imaginary parts of the complex refractive index (n({lambda})+ik({lambda})) and the ideal absorption coefficients via classical dispersion fits to our reflectance spectra.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/85
- Title:
- RELICS: Reionization Lensing Cluster Survey
- Short Name:
- J/ApJ/884/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Large surveys of galaxy clusters with the Hubble Space Telescope (HST) and Spitzer, including the Cluster Lensing And Supernova survey with Hubble and the Frontier Fields, have demonstrated the power of strong gravitational lensing to efficiently deliver large samples of high-redshift galaxies. We extend this strategy through a wider, shallower survey named RELICS, the Reionization Lensing Cluster Survey, described here. Our 188-orbit Hubble Treasury Program observed 41 clusters at 0.182<=z<=0.972 with Advanced Camera for Surveys (ACS) and WFC3/IR imaging spanning 0.4-1.7{mu}m. We selected 21 of the most massive clusters known based on Planck PSZ2 estimates and 20 additional clusters based on observed or inferred lensing strength. RELICS observed 46 WFC3/IR pointings (~200arcmin^2^) each with two orbits divided among four filters (F105W, F125W, F140W, and F160W) and ACS imaging as needed to achieve single-orbit depth in each of three filters (F435W, F606W, and F814W). As previously reported by Salmon+ (2020ApJ...889..189S), we discovered over 300 z~6-10 candidates, including the brightest z~6 candidates known, and the most distant spatially resolved lensed arc known at z~10. Spitzer IRAC imaging (945hr awarded, plus 100 archival, spanning 3.0-5.0{mu}m) has crucially enabled us to distinguish z~10 candidates from z~2 interlopers. For each cluster, two HST observing epochs were staggered by about a month, enabling us to discover 11 supernovae, including 3 lensed supernovae, which we followed up with 20 orbits from our program.
- ID:
- ivo://CDS.VizieR/J/A+A/365/545
- Title:
- Remnant disks around main-sequence stars IR flux
- Short Name:
- J/A+A/365/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric ISO 60 and 170{mu}m measurements, complemented by some IRAS data at 60{mu}m, of a sample of 84 nearby main-sequence stars of spectral class A, F, G and K in order to determine the incidence of dust disks around such main-sequence stars. Fifty stars were detected at 60{mu}m; 36 of these emit a flux expected from their photosphere while 14 emit significantly more. The excess emission we attribute to a circumstellar disk like the ones around Vega and {beta} Pictoris. Thirty four stars were not detected at all; the expected photospheric flux, however, is so close to the detection limit that the stars cannot have an excess stronger than the photospheric flux density at 60{mu}m. Of the stars younger than 400Myr one in two has a disk; for the older stars this is true for only one in ten. We conclude that most stars arrive on the main sequence surrounded by a disk; this disk then decays in about 400Myr. Because (i) the dust particles disappear and must be replenished on a much shorter time scale and (ii) the collision of planetesimals is a good source of new dust, we suggest that the rapid decay of the disks is caused by the destruction and escape of planetesimals. We suggest that the dissipation of the disk is related to the heavy bombardment phase in our Solar System. Whether all stars arrive on the main sequence surrounded by a disk cannot be established: some very young stars do not have a disk. And not all stars destroy their disk in a similar way: some stars as old as the Sun still have significant disks.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A85
- Title:
- Resolved IR spectra of pure CO2 ice (15-75K)
- Short Name:
- J/A+A/555/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The v2 bending mode of pure CO_2_ ice around 15.2um exhibits a fine double-peak structure that offers a sensitive probe to study the physical and chemical properties of solid CO_2_ in space. Current laboratory spectra do not fully resolve the CO_2_ ice features. To improve the fitting of the observed CO_2_ features, high-resolution solid-state infrared spectra of pure CO_2_ ice are recorded in the laboratory for a series of astronomically relevant temperatures and at an unprecedented level of detail. The infrared spectra of pure CO_2_ ice were recorded in the 4000 to 400cm^-1^ (2.5-25um) region at a resolution of 0.1cm^-1^ using Fourier transform infrared spectroscopy. Accurate band positions and band widths (FWHM) of pure CO_2_ ice are presented for temperatures of 15, 30, 45, 60, and 75K. The focus of this spectroscopic work is on the CO_2_ (v2) bending mode, but more accurate data are also reported for the ^12^CO_2_ and ^13^CO_2_ (v3) stretching mode, and CO_2_ (v1+v3) and (2v2+v3) combination bands.
- ID:
- ivo://CDS.VizieR/III/237A
- Title:
- Revised Byurakan-IRAS stars (BIS) catalog
- Short Name:
- III/237A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Five lists of late-type stars were published in Astrophysics in 1997-2001, found in the First Byurakan Survey low-dispersion spectroscopic plates as optical identifications of unidentified IRAS sources. These identifications were carried out in the region with DE>+61 and |b|>15 with a surface of 1504deg^2^. As a result, the catalog of the Byurakan-IRAS Stars (BIS) was compiled. Its preliminary version was available at CDS since 2003, Cat. <III/237>. We have revised and updated the BIS catalog with the new data from recently published optical and infrared catalogs to give access to all available data and make possible further comparative studies of the properties of these objects. Cross-correlations of the BIS catalogue with the MAPS, USNO-B1.0 and 2MASS are made, updated SIMBAD data for the BIS objects are added, and accurate DSS1 and DSS2 positions and revised photometry are provided. The objects were checked for proper motion and variability as well. A refined classification from the Digitized First Byurakan Survey (DFBS) low-dispersion spectra was carried out. The revised and updated catalogue of 276 Byurakan-IRAS stars (BIS) is presented. The BIS catalogue can be used for a study of a complete sample of IRAS selected stars and for investigation of individual objects.
- ID:
- ivo://CDS.VizieR/III/266
- Title:
- Revised First Byurakan Survey of late-type stars
- Short Name:
- III/266
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1990 and 2010, 15 lists of late-type stars found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS) were published. The systematic search and selection was carried out on a surface of 16000 sq.deg. on almost the whole area of the FBS. As a result, a comprehensive catalogue of the late-type stars of the FBS was generated. Its preliminary version has been available at the CDS since 2007 (Cat. III/246). We have revised and updated the FBS catalogue of late-type stars with new data from recently published optical and multiwavelength catalogues to give access to all available data and to make further comparative studies of the properties of these objects possible. We have made cross-correlations with the Digitized First Byurakan Survey (DFBS, Cat. VI/116)), the United States Naval Observatory-B1.0 catalogue (Cat. I/284), the Guide Star Catalogue 2.3.2 (Cat. I/305), Tycho-2 (Cat. I/259), Sloan Digital Sky Survey Data Release 8 (Cat. II/306), the Two-Micron All-Sky Survey (2MASS, Cat. II/246)), the Wide-field Infrared Survey Explorer catalogue (WISE, Cat. II/311), the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue (IRAS Catalogs II/125, II/156), the AKARI catalogue (Cat. II/297), the ROSAT Bright Source Catalogue (IX/10) and Faint Source (IX/29) Catalogues, the General Catalogue of Variable Stars (B/gcvs) and the Northern Sky Variability Survey. Also, we have added updated SIMBAD data for the objects. We present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours and available proper motions for 1045 FBS late-type stars. The FBS revised and updated catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint carbon stars at high Galactic latitudes and M dwarfs in the vicinity of the Sun. We study the complete samples, as well as investigating individual interesting objects up to 16.0-16.5mag in visual.
- ID:
- ivo://CDS.VizieR/J/ApJS/112/109
- Title:
- Rho Oph Near-IR Positions and Photometry
- Short Name:
- J/ApJS/112/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the tabulated results from a three-color (JHK) near-Infrared imaging survey of the Rho Ophiuchi star-forming cloud core. The NIR imaging observations were acquired using the SQIID instrument on the Kitt Peak 1.3m telescope from June 4-10, 1993 and April 23-28, 1994. The survey covered one square degree (2.2pc by 2.2pc). The catalog contains 4495 sources with both J2000.0 and B1950.0 coordinates for each source and its J, H, and K magnitudes and/or upper their limits. The Rho Ophiuchi clouds are of great interest for star formation studies, since they include the nearest example of a currently forming star cluster. The absolute positions in RA and Dec were determined for each individual source by using a centering algorithm in the IRAF package APPHOT to obtain center positions in pixels which were then merged into a single common positional grid. Absolute stellar coordinates were determined by comparing the authors positional database with the positions of 36 HST Guide Star Catalog stars spread out over the survey field. These were used to determine a plate scale and rotation which was used to generate the final list of source positions. The position determination technique and the photometric data reduction and calibration is discussed in detail in the source reference.
980. RMS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/4029
- Title:
- RMS survey
- Short Name:
- J/MNRAS/452/4029
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of ammonia observations towards 66 massive star forming regions identified by the Red Midcourse Space Experiment Source survey. We have used the Green Bank Telescope and the K-Band Focal Plane Array to map the ammonia (NH_3_) (1,1) and (2,2) inversion emission at a resolution of 30 arcsec in 8 arcmin regions towards the positions of embedded massive star formation. We have identified a total of 115 distinct clumps, approximately two-thirds of which are associated with an embedded massive young stellar object or compact HII region, while the others are classified as quiescent. There is a strong spatial correlation between the peak NH3 emission and the presence of embedded objects. We derive the spatial distribution of the kinetic gas temperatures, line widths, and NH3 column densities from these maps, and by combining these data with dust emission maps we estimate clump masses, H_2_ column densities and ammonia abundances. The clumps have typical masses of ~1000M_{sun}_ and radii ~0.5pc, line widths of ~2km/s and kinetic temperatures of ~16-20K. We find no significant difference between the sizes and masses of the star-forming and quiescent subsamples; however, the distribution maps reveal the presence of temperature and line width gradients peaking towards the centre for the star-forming clumps while the quiescent clumps show relatively uniform temperatures and line widths throughout. Virial analysis suggests that the vast majority of clumps are gravitationally bound and are likely to be in a state of global free fall in the absence of strong magnetic fields. The similarities between the properties of the two subsamples suggest that the quiescent clumps are also likely to form massive stars in the future, and therefore provide an excellent opportunity to study the initial conditions of massive pre-stellar and protostellar clumps.
