- ID:
- ivo://CDS.VizieR/J/AJ/124/1651
- Title:
- Faint high-latitude carbon stars SDSS photometry
- Short Name:
- J/AJ/124/1651
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 39 faint high-latitude carbon stars (FHLCs) from Sloan Digital Sky Survey (SDSS) commissioning data. The objects, each selected photometrically and verified spectroscopically, range over 16.6<r*<20.0 and show a diversity of temperatures as judged by both colors and NaD line strengths. Although a handful of these stars were previously known, these objects are, in general, too faint and too warm to be effectively identified in other modern surveys such as the Two Micron All Sky Survey, nor are their red/near-IR colors particularly distinctive. We present proper-motion measures for each object, indicating that the sample is a mixture of extremely distant (greater than 100kpc) halo giant stars, useful for constraining halo dynamics, and members of the recently recognized exotic class of very nearby dwarf carbon (dC) stars.
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- ID:
- ivo://CDS.VizieR/J/AJ/127/2838
- Title:
- Faint high-latitude carbon stars SDSS photometry
- Short Name:
- J/AJ/127/2838
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search of more than 3000deg^2^ of high-latitude sky by the Sloan Digital Sky Survey has yielded 251 faint high-latitude carbon stars (FHLCs), the large majority previously uncatalogued. We present homogeneous spectroscopy, photometry, and astrometry for the sample. The objects lie in the 15.6<r<20.8 range and exhibit a wide variety of apparent photospheric temperatures, ranging from spectral types near M to as early as F. Proper-motion measurements for 222 of the objects show that at least 50%, and quite probably more than 60%, of these objects are actually low-luminosity dwarf carbon (dC) stars, in agreement with a variety of recent, more limited investigations that show that such objects are the numerically dominant type of star with C_2_ in the spectrum. This SDSS homogeneous sample of ~110 dC stars now constitutes 90% of all known carbon dwarfs and will grow by another factor of 2-3 by the completion of the survey. As the spectra of the dC and the faint halo giant C stars are very similar (at least at spectral resolution of 10^3^), despite a difference of 10mag in luminosity, it is imperative that simple luminosity discriminants other than proper motion be developed. We use our enlarged sample of FHLCs to examine a variety of possible luminosity criteria, including many previously suggested, and find that, with certain important caveats, JHK photometry may segregate dwarfs and giants.
- ID:
- ivo://CDS.VizieR/J/AJ/152/91
- Title:
- Faint UBVRI standard stars at +50{deg} declination
- Short Name:
- J/AJ/152/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise and accurate CCD-based UBVRI photometry is presented for ~2000 stars distributed around the sky in a declination zone centered approximately at +50{deg}. Their photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems through observations of the UBVRI standard stars presented in the various works of Landolt. The magnitude and color range for these stars are 12<~V<~22 and -0.3<~(B-V)<~1.8, respectively. Each star averages 13 measures in each UBVRI filter from data taken on 41 different photometric nights obtained over a 21 month period. Hence, there now exists a network of faint UBVRI photometric standard stars centered on the declination zones {delta}=-50{deg}, 0{deg}, and +50{deg}.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/1672
- Title:
- Far-IR and H{alpha} fluxes in galaxies
- Short Name:
- J/ApJ/703/1672
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine H{alpha} emission-line and infrared (IR) continuum measurements of two samples of nearby galaxies to derive dust attenuation-corrected star formation rates (SFRs). We use a simple energy balance based method that has been applied previously to HII regions in the Spitzer Infrared Nearby Galaxies Survey, and extend the methodology to integrated measurements of galaxies. We find that our composite H{alpha}+IR based SFRs are in excellent agreement with attenuation-corrected SFRs derived from integrated spectrophotometry, over the full range of SFRs (0.01-80M_{sun}_/yr) and attenuations (0-2.5mag) studied. The calibrations differ significantly from those obtained for HII regions, with the difference attributable to a more evolved population of stars heating the dust. Our results are consistent with a significant component of diffuse dust (the "IR cirrus" component) that is heated by a non-star-forming population.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/1880
- Title:
- Far-IR properties of VCC galaxies
- Short Name:
- J/MNRAS/428/1880
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Virgo Cluster Survey (HeViCS) is the deepest, confusion-limited survey of the Virgo Cluster at far-infrared (FIR) wavelengths. The entire survey at full depth covers ~55deg^2^ in five bands (100-500um), encompassing the areas around the central dominant elliptical galaxies (M87, M86 and M49) and extends as far as the NW cloud, the W cloud and the Southern extension. The survey extends beyond this region with lower sensitivity so that the total area covered is 84 deg2. In this paper we describe the data, the data acquisition techniques and present the detection rates of the optically selected Virgo Cluster Catalogue (VCC). We detect 254 (34%) of 750 VCC galaxies found within the survey boundary in at least one band and 171 galaxies are detected in all five bands. For the remainder of the galaxies we have measured strict upper limits for their FIR emission.
- ID:
- ivo://CDS.VizieR/J/A+A/384/491
- Title:
- Fast-rotating nearby solar-type stars. I.
- Short Name:
- J/A+A/384/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of high-resolution spectroscopic and high-precision photometric observations on a sample of 129 late-F and G-type nearby stars selected on the basis of their large rotational velocity. Using also data from the Hipparcos satellite, CORAVEL and from the ROSAT satellite database, we infer spectral types, compute radial velocities, vsini, Li abundances and X-ray luminosities and investigate the single or binary nature of the sample stars. Such a careful analysis of our sample shows a large fraction of binaries (~62%) and of young single disk stars. In particular, at least 9 stars can be considered bona-fide PMS or ZAMS objects, and 30 stars are identified as SBs for the first time. Information on the presence of Ca II K emission and on optical variability is given for some of the stars of the sample. The photometry has been obtained at the European Southern Observatory (ESO-La silla, Chile) during several observing runs (19/11-03/12 1993, 24/11-04/12 1994, 15-28/01/1995 and 1-12/10/1995), by using the 50cm ESO telescope. The figures were published in paper II.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/52
- Title:
- 8 Fermi GRB afterglows follow-up
- Short Name:
- J/ApJ/806/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi Gamma-ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi GRB Monitor instrument have posed a formidable obstacle to locating the bursts' host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target-of-opportunity (TOO) mode for the intermediate Palomar Transient Factory (iPTF) in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: 8 afterglow discoveries out of 35 searches. Two of the bursts with detected afterglows (GRBs 130702A and 140606B) were at low redshift (z=0.145 and 0.384, respectively) and had spectroscopically confirmed broad-line Type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samples. We identify one new outlier on the Amati relation. We find that two bursts are consistent with a mildly relativistic shock breaking out from the progenitor star rather than the ultra-relativistic internal shock mechanism that powers standard cosmological bursts. Finally, in the context of the Zwicky Transient Facility, we discuss how we will continue to expand this effort to find optical counterparts of binary neutron star mergers that may soon be detected by Advanced LIGO and Virgo.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/197
- Title:
- F, G and K stars BVRI photometry
- Short Name:
- J/A+AS/131/197
- Date:
- 15 Dec 2021 08:12:40
- Publisher:
- CDS
- Description:
- We present accurate BV(RI)c photometry for a sample of F, G and K stars detected in selected areas of the ROSAT all-sky survey (RASS). We have used the photometry, in addition to low-resolution spectroscopy, to estimate spectral classifications, distances and X-ray luminosities. The log(L_X_/L_V_) in the sample lies below -2. Although the sample contains also nearby, inactive stars, it is dominated by active objects. The median X-ray luminosity in our sample is <L_X_>=29.88 and the mean value of the hardness ratios <HR1>=0.13+/-0.35. We compare the derived X-ray luminosity function with similar functions obtained from the serendipitous samples of the Einstein Observatory medium sensitivity survey (EMSS, Cat. <IX/15>) and EXOSAT (Cat. <J/A+AS/115/41>). Our sample is completely consistent with the EMSS sample of solar type stars, indicating that both our sources and the EMSS sources are representative of the high galactic latitude X-ray stellar population. We do not find extremely active stars (log(L_X_)>=32), as are found in the EMSS sample, and we argue that these objects are rare.
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/1467
- Title:
- Field early-type galaxies at 0.2<z<0.8
- Short Name:
- J/MNRAS/393/1467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the properties of 24 field early-type galaxies in the redshift range 0.20<z<0.75 down to M_B<=-19.30 in a sample extracted from the FORS Deep Field and the William Herschel Deep Field. Target galaxies were selected on the basis of a combination of luminosity, spectrophotometric type, morphology and photometric redshift or broad-band colours. High signal-to-noise intermediate-resolution spectroscopy has been acquired at the Very Large Telescope, complemented by deep high-resolution imaging with the Advanced Camera for Surveys onboard the HST and additional ground-based multi-band photometry. All galaxy spectra were observed under sub-arcsecond conditions and allow to derive accurate kinematics and stellar population properties of the galaxies. To clarify the low level of star formation detected in some galaxies, we identify the amount of active galactic nuclei (AGN) activity in our sample using archive data of Chandra and XMM-Newton X-ray surveys. None of the galaxies in our sample were identified as secure AGN sources based on their X-ray emission. The rest-frame B and K-band scaling relations of the Faber-Jackson relation and the Fundamental Plane display a moderate evolution for the field early-type galaxies. Lenticular (S0) galaxies feature on average a stronger luminosity evolution and bluer rest-frame colours which can be explained that they comprise more diverse stellar populations compared to elliptical galaxies. The evolution of the FP can be interpreted as an average change in the dynamical (effective) mass-to-light ratio of our galaxies as <{Delta}log(M/L_B_)/z>=-0.74+/-0.08. The M/L evolution of these field galaxies suggests a continuous mass assembly of field early-type galaxies during the last 5Gyr, that gets support by recent studies of field galaxies up to z~1. Independent evidence for recent star formation activity is provided by spectroscopic (OII emission, Hdelta) and photometric (rest-frame broad-band colors) diagnostics. Based on the Hdelta absorption feature we detect a weak residual star formation for galaxies that accounts for 5%-10% in the total stellar mass of these galaxies. The co-evolution in the luminosity and mass of our galaxies favours a downsizing formation process. We find some evidence that our galaxies experienced a period of star formation quenching, possible triggered by AGN activity that is in good agreement with recent results on both observational and theoretical side.
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/2182
- Title:
- FIR bright sources of M83
- Short Name:
- J/MNRAS/432/2182
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate star formation and dust heating in the compact far-infrared (FIR) bright sources detected in the Herschel maps of M83. We use the source extraction code GETSOURCES to detect and extract sources in the FIR, as well as their photometry in the mid-infrared and H{alpha}. By performing infrared spectral energy distribution fitting and applying an H{alpha}-based star formation rate (SFR) calibration, we derive the dust masses and temperatures, SFRs, gas masses and star formation efficiencies (SFEs). The detected sources lie exclusively on the spiral arms and represent giant molecular associations, with gas masses and sizes of 106-108M{sun} and 200-300pc, respectively. The inferred parameters show little to no radial dependence and there is only a weak correlation between the SFRs and gas masses, which suggests that more massive clouds are less efficient at forming stars. Dust heating is mainly due to local star formation. However, although the sources are not optically thick, the total intrinsic young stellar population luminosity can almost completely account for the dust luminosity. This suggests that other radiation sources also contribute to the dust heating and approximately compensate for the unabsorbed fraction of UV light.