- ID:
- ivo://CDS.VizieR/J/AJ/115/1856
- Title:
- Dwarf Cepheids in Carina
- Short Name:
- J/AJ/115/1856
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have discovered 20 dwarf Cepheids (DCs) in the Carina dwarf spheroidal galaxy from an analysis of individual CCD images obtained for a deep photometric study of the system. These short-period pulsating variable stars are by far the most distant (~100kpc) and faintest (V~23.0) DCs known. The Carina DCs obey a well-defined period-luminosity relation, allowing us to readily distinguish between overtone and fundamental pulsators in nearly every case. Unlike RR Lyrae stars, the pulsation mode turns out to be uncorrelated with light-curve shape, and the overtone pulsators do not tend toward shorter periods compared with the fundamental pulsators. Using the period-luminosity relations from Nemec, Nemec, & Lutz (1994, Cat. <J/AJ/108/222> and McNamara (1995AJ....109.1751M), we derive (m-M)_0_=20.06+/-0.12, for E(B-V)=0.025 and [Fe/H]=-2.0, in good agreement with recent, independent estimates of the distance/reddening of Carina. The error reflects the uncertainties in the DC distance scale, and in the metallicity and reddening of Carina. The frequency of DCs among upper-main-sequence stars in Carina is approximately 3%. The ratio of dwarf Cepheids to RR Lyrae stars in Carina is 0.13+/-0.10, though this result is highly sensitive to the star formation history of Carina and the evolution of the horizontal branch.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/813/L15
- Title:
- Dwarf galaxies in Fornax cluster from NGFS
- Short Name:
- J/ApJ/813/L15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of 158 previously undetected dwarf galaxies in the Fornax cluster central regions using a deep coadded u-, g-, and i-band image obtained with the Dark Energy Camera wide-field camera mounted on the 4-m Blanco telescope at the Cerro Tololo Interamerican Observatory as part of the Next Generation Fornax Survey (NGFS). The new dwarf galaxies have quasi-exponential light profiles, effective radii 0.1<r_e_<2.8kpc, and average effective surface brightness values 22.0<{mu}_i_<28.0mag/arcsec2. We confirm the existence of ultra-diffuse galaxies (UDGs) in the Fornax core regions that resemble counterparts recently discovered in the Virgo and Coma galaxy clusters. We also find extremely low surface brightness NGFS dwarfs, which are several magnitudes fainter than the classical UDGs. The faintest dwarf candidate in our NGFS sample has an absolute magnitude of M_i_=-8.0mag. The nucleation fraction of the NGFS dwarf galaxy sample appears to decrease as a function of their total luminosity, reaching from a nucleation fraction of >75% at luminosities brighter than M_i_~=-15.0mag to 0% at luminosities fainter than M_i_~=-10.0mag. The two-point correlation function analysis of the NGFS dwarf sample shows an excess on length scales below ~100 kpc, pointing to the clustering of dwarf galaxies in the Fornax cluster core.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/1484
- Title:
- Early optical afterglow catalog
- Short Name:
- J/ApJ/693/1484
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolor optical observations of long-duration {gamma}-ray bursts (GRBs) made over a three-year period with the robotic Palomar 60 inch telescope (P60). Our sample consists of all 29 events discovered by Swift for which P60 began observations less than 1hr after the burst trigger. We were able to recover 80% of the optical afterglows from this prompt sample, and we attribute this high efficiency to our red coverage. Like Melandri et al. (2008, Cat. J/ApJ/686/1209), we find that a significant fraction (~50%) of Swift events show a suppression of the optical flux with regard to the X-ray emission (the so-called "dark" bursts). Our multicolor photometry demonstrates this is likely due in large part to extinction in the host galaxy. We argue that previous studies, by selecting only the brightest and best-sampled optical afterglows, have significantly underestimated the amount of dust present in typical GRB environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/61
- Title:
- Early-type EBs with intermediate orbital periods
- Short Name:
- J/ApJ/810/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze 221 eclipsing binaries (EBs) in the Large Magellanic Cloud with B-type main-sequence (MS) primaries (M_1_~4-14 M_{sun}_) and orbital periods P=20-50 days that were photometrically monitored by the Optical Gravitational Lensing Experiment. We utilize our three-stage automated pipeline to (1) classify all 221 EBs, (2) fit physical models to the light curves of 130 detached well-defined EBs from which unique parameters can be determined, and (3) recover the intrinsic binary statistics by correcting for selection effects. We uncover two statistically significant trends with age. First, younger EBs tend to reside in dustier environments with larger photometric extinctions, an empirical relation that can be implemented when modeling stellar populations. Second, younger EBs generally have large eccentricities. This demonstrates that massive binaries at moderate orbital periods are born with a Maxwellian "thermal" orbital velocity distribution, which indicates they formed via dynamical interactions. In addition, the age-eccentricity anticorrelation provides a direct constraint for tidal evolution in highly eccentric binaries containing hot MS stars with radiative envelopes. The intrinsic fraction of B-type MS stars with stellar companions q=M_2_/M_1_>0.2 and orbital periods P=20-50 days is (7+/-2)%. We find early-type binaries at P=20-50 days are weighted significantly toward small mass ratios q~0.2-0.3, which is different than the results from previous observations of closer binaries with P<20 days. This indicates that early-type binaries at slightly wider orbital separations have experienced substantially less competitive accretion and coevolution during their formation in the circumbinary disk.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/1879
- Title:
- EC Blue Object survey. -40{deg}>b>-50{deg}
- Short Name:
- J/MNRAS/453/1879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results for Zone 3 of the Edinburgh-Cape (EC) Blue Object survey are presented. This zone covers that part of the South Galactic Cap between 40{deg} and 50{deg} from the Galactic plane and south of about -12.3{deg} of declination. EC Zone 3 contains 53 UK Schmidt Telescope fields covering about 1400 deg2 in which we find some 534 blue objects, including hot subdwarfs (~39 percent), white dwarfs (~21 percent), cataclysmic variables (~2 percent) and some star-like galaxies (~9 percent). A further 178 cooler stars observed in the survey, including low-metallicity F- and G-type stars, are also listed. Both low-dispersion spectroscopic classification and UBV photometry are presented for almost all of the hot objects and either spectroscopy or photometry (sometimes both) for the cooler ones.
- ID:
- ivo://CDS.VizieR/J/ApJ/796/60
- Title:
- ECDFS galaxies photometric redshifts & counterparts
- Short Name:
- J/ApJ/796/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). This work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy Survey (CANDELS) and the Taiwan ECDFS Near-Infrared Survey (TENIS) in addition to other data. We also revisit multi-wavelength counterparts for published X-ray sources from the 4Ms CDFS and 250ks ECDFS surveys, finding reliable counterparts for 1207 out of 1259 sources (~96%). Data used for photometric redshifts include intermediate-band photometry deblended using the TFIT method, which is used for the first time in this work. Photometric redshifts for X-ray source counterparts are based on a new library of active galactic nuclei/galaxy hybrid templates appropriate for the faint X-ray population in the CDFS. Photometric redshift accuracy for normal galaxies is 0.010 and for X-ray sources is 0.014 and outlier fractions are 4% and 5.2%, respectively. The results within the CANDELS coverage area are even better, as demonstrated both by spectroscopic comparison and by galaxy-pair statistics. Intermediate-band photometry, even if shallow, is valuable when combined with deep broadband photometry. For best accuracy, templates must include emission lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/L13
- Title:
- ECDFS MUSYC galaxies UBVRIzNB5000 photometry
- Short Name:
- J/ApJ/642/L13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We selected 40 candidate Ly{alpha}-emitting galaxies (LAEs) at z~3.1 with observed-frame equivalent widths greater than 150{AA} and inferred emission-line fluxes above 2.5x10^-17^ergs/cm^2^/s from deep narrowband and broadband MUSYC images of the Extended Chandra Deep Field South. Covering 992-arcmin^2^, this is the largest "blank field" surveyed for LAEs at z~3, allowing an improved estimate of the space density of this population of (3+/-1)x10^4^h/Mpc^3^. Spectroscopic follow-up of 23 candidates yielded 18 redshifts, all at z~3.1. Over 80% of the LAEs are dimmer in continuum magnitude than the typical Lyman break galaxy (LBG) spectroscopic limit of R=25.5 (AB), with a median continuum magnitude R~27 and very blue continuum colors, V-z~=0.
- ID:
- ivo://CDS.VizieR/J/A+A/506/501
- Title:
- Eclipsing binaries in CoRoT-LRc01 field
- Short Name:
- J/A+A/506/501
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present here the list of planetary transit candidates detected in the first long run observed by CoRoT: LRc01, towards the galactic center in the direction of Aquila, which lasted from May to October 2007. We analyzed 3719 (33%) sources in the chromatic bands and 7689 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, on which subsequently several transit search algorithms were applied. Forty two sources were classified as planetary transit candidates and up to now 26 cases have been solved. One planet (CoRoT-2b) and one brown-dwarf (CoRoT-3b) have been the subjects of detailed publications.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/89
- Title:
- Eclipsing LMXB at the center of 3FGL J0427.9-6704
- Short Name:
- J/ApJ/831/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of an eclipsing low-mass X-ray binary at the center of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope {gamma}-ray source 3FGL J0427.9-6704. Photometry from OGLE and the SMARTS 1.3m telescope and spectroscopy from the SOAR telescope have allowed us to classify the system as an eclipsing low-mass X-ray binary (P=8.8hr) with a main-sequence donor and a neutron-star accretor. Broad double-peaked H and He emission lines suggest the ongoing presence of an accretion disk. Remarkably, the system shows separate sets of absorption lines associated with the accretion disk and the secondary, and we use their radial velocities to find evidence for a massive (~1.8-1.9M_{sun}_) neutron-star primary. In addition to a total X-ray eclipse with a duration of ~2200s observed with NuSTAR, the X-ray light curve also shows properties similar to those observed among known transitional millisecond pulsars: short-term variability, a hard power-law spectrum ({Gamma}~1.7), and a comparable 0.5-10keV luminosity (~2.4x10^33^erg/s). We find tentative evidence for a partial (~60%) {gamma}-ray eclipse at the same phase as the X-ray eclipse, suggesting the {gamma}-ray emission may not be confined to the immediate region of the compact object. The favorable inclination of this binary is promising for future efforts to determine the origin of {gamma}-rays among accreting neutron stars.
- ID:
- ivo://CDS.VizieR/J/A+A/492/637
- Title:
- Eddington ratios of faint AGN
- Short Name:
- J/A+A/492/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use one of the deepest spectroscopic samples of broad-line active galactic nuclei (AGN) currently available, extracted from the VIMOS VLT Deep Survey (VVDS, Cat. <III/250>), to compute the MgII and CIV virial-mass estimates of 120 super-massive black holes in the redshift range 1.0<z<1.9 and 2.6<z<4.3.
