- ID:
- ivo://CDS.VizieR/J/ApJS/191/124
- Title:
- Optical spectroscopy of ECDF-S X-ray sources
- Short Name:
- J/ApJS/191/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2Ms area. New spectroscopic redshifts, up to z=4, are measured for 283 counterparts to Chandra sources with deep exposures (t~2-9hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since our new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250ks coverage, we provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. Our redshift catalog includes 17 type-2 QSOs at 1<~z<~3.5. Based on our deepest (9 hr) VLT/VIMOS observation, we identify "elusive" optically faint galaxies (Rmag~25) at z~2-3 based upon the detection of interstellar absorption lines (e.g., OII+SiIV, CII], CIV).
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- ID:
- ivo://CDS.VizieR/J/ApJ/860/49
- Title:
- Optical spectroscopy of young {alpha}-rich stars
- Short Name:
- J/ApJ/860/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report chemical abundances of 14 young {alpha}-rich stars including neutron-capture elements based on high-quality optical spectra from HIRES/Keck I and differential line-by-line analysis. From a comparison of the abundance patterns of young {alpha}-rich stars to those of nearby bright red giants with a similar metallicity range (-0.7<[Fe/H]{<}-0.2), we confirm their high {alpha}-element abundances reported by previous studies based on near-infrared spectroscopy. We reveal for the first time low abundances of s-process elements and high abundances of r-process elements. All the abundances are consistent with those seen in the typical {alpha}-rich population of the Galactic disk, and no abundance anomalies are found except for Li-enhancement in one object previously reported and mild enhancement of Na in two stars. In particular, the lack of s-process enhancement excludes the hypothesis that mass transfer from asymptotic giant branch stars plays an important role in the formation of young {alpha}-rich stars. The high frequency of radial velocity variation (more than 50%) is also confirmed. We argue that mass transfer from low-mass red giants is the likely dominant formation mechanism for young {alpha}-rich stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/138
- Title:
- Optical spectroscopy toward Orion B fields
- Short Name:
- J/ApJ/844/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from high-resolution optical spectra toward 66 young stars in the Orion B molecular cloud to study their kinematics and other properties. Observations of the H{alpha} and Li I 6707{AA} lines are used to check membership and accretion properties. While the stellar radial velocities of NGC 2068 and L1622 are in good agreement with that of the molecular gas, many of the stars in NGC 2024 show a considerable offset. This could be a signature of either the expansion of the cluster, the high degree of the ejection of the stars from the cluster through dynamical interaction, or the acceleration of the gas due to stellar feedback.
- ID:
- ivo://CDS.VizieR/J/ApJ/895/49
- Title:
- Optical spectrum of ZTF18abvkwla and its host galaxy
- Short Name:
- J/ApJ/895/49
- Date:
- 16 Mar 2022 00:26:26
- Publisher:
- CDS
- Description:
- We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT2018cow: blue colors at peak (g-r~-0.5mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity (M_g.peak_~-20.6mag), a hot (>~40000K) featureless spectrum at peak light, and a luminous radio counterpart. At late times ({Delta}>80days), the radio luminosity of ZTF18abvkwla ({nu}L_{nu}_>~10^40^erg/s at 10GHz, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy (M~5x10^8^M{odot}, SFR~7M{odot}/yr) that is moderately metal-enriched (log[O/H]~8.5), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast- moving ejecta ({Gamma}{beta}c>0.38c) and the optical from shock-interaction with confined dense material (<0.07M{sun} in ~10^15^cm). Compiling transients in the literature with t_rise_<5days and M_peak_<-20mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, as well as prospects for detecting accompanying X-ray and radio emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/3
- Title:
- Optical & Spitzer photometry in IC 1805
- Short Name:
- J/ApJS/230/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep wide-field optical CCD photometry and mid-infrared Spitzer/IRAC and MIPS 24{mu}m data for about 100000 stars in the young open cluster IC 1805. The members of IC 1805 were selected from their location in the various color-color and color-magnitude diagrams, and the presence of H{alpha} emission, mid-infrared excess emission, and X-ray emission. The reddening law toward IC 1805 is nearly normal (R_V_=3.05+/-0.06). However, the distance modulus of the cluster is estimated to be 11.9+/-0.2mag (d=2.4+/-0.2kpc) from the reddening-free color-magnitude diagrams, which is larger than the distance to the nearby massive star-forming region W3(OH) measured from the radio VLBA astrometry. We also determined the age of IC 1805 ({tau}_MSTO_=3.5Myr). In addition, we critically compared the age and mass scale from two pre-main-sequence evolution models. The initial mass function with a Salpeter-type slope of {Gamma}=-1.3+/-0.2 was obtained and the total mass of IC 1805 was estimated to be about 2700+/-200M_{sun}_. Finally, we found our distance determination to be statistically consistent with the Tycho-Gaia Astrometric Solution Data Release 1, within the errors. The proper motion of the B-type stars shows an elongated distribution along the Galactic plane, which could be explained by some of the B-type stars being formed in small clouds dispersed by previous episodes of star formation or supernova explosions.
- ID:
- ivo://CDS.VizieR/J/ApJ/537/101
- Title:
- Optical Study for blazars. I.
- Short Name:
- J/ApJ/537/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric observations of AGNs are important to construct light curves and to study variability behavior over different timescales. In this paper, the historical optical data compiled from the published literature are presented in tabular form as an optical database for 28 radio-selected BL Lacertae objects. Maximum optical variations are found and compared with the infrared ones. The faintest, brightest, and averaged magnitudes are presented for individual object. The variation is found correlated with polarization. The light curves are shown in figures along with the relation between color index and magnitude. For the color-magnitude relation, two objects, 0735+178 and 0537-441, show evidence that the color index increases with magnitude, indicating that the spectrum flattens when the source brightens, while three objects (0219+428, 1514-241, 2200+420) show the opposite behavior; an object, 0235+164, shows a brightness-dependent color index- magnitude correlation, while the rest of the objects do not show any clear tendency.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/3094
- Title:
- Optical transit light curves of WASP-57
- Short Name:
- J/MNRAS/454/3094
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 transit light curves from professional facilities which confirm and refine this finding, and high-resolution imaging which show no evidence for nearby companions. We use these data to determine a new and precise orbital ephemeris, and measure the physical properties of the system. Our revised orbital period is 4.5 s shorter than found from the discovery data alone, which explains the early occurrence of the transits. We also find both the star and planet to be larger and less massive than previously thought. The measured mass and radius of the planet are now consistent with theoretical models of gas giants containing no heavy-element core, as expected for the subsolar metallicity of the host star. Two transits were observed simultaneously in four passbands. We use the resulting light curves to measure the planet's radius as a function of wavelength, finding that our data are sufficient in principle but not in practise to constrain its atmospheric properties. We conclude with a discussion of the current and future status of transmission photometry studies for probing the atmospheres of gas-giant transiting planets.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/725
- Title:
- Optical-UV-IR survey of North Celestial Cap
- Short Name:
- J/MNRAS/443/725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the final product of the North Celestial Cap Survey (NCCS) - the optical-UV-IR merged catalogue for the region within 10{deg} of the North Celestial Pole. The North Celestial Cap (NCC) region at {delta}>=80{deg} is poorly covered by modern CCD-based surveys. The optical part of the survey was observed in V, R and I with the Wide-field Infrared Survey Explorer (WISE) Observatory telescopes and was merged with GALEX UV and WISE IR data, producing the catalogue. More than four million objects were observed in at least one optical band. The final catalogue contains ~1.6 million sources observed in all three optical bands, of which some 1.4 million have WISE counterparts and ~300000 have GALEX counterparts. The astrometric accuracy of the optical NCCS data, derived from a comparison with the UCAC3 catalogue, is better than 0.2-arcsec and the photometry, when compared with Sloan Digital Sky Survey, is good to ~0.15mag for sources brighter than V=20.3, R=21.0 and I=19.2mag. The Sloan Digital Sky Survey point-extended source separation is reproduced with >92 per cent efficiency.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/403
- Title:
- Optical Variabilities in 3C 120
- Short Name:
- J/PAZh/35/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on our UBVRI observations and X-ray data from the RXTE satellite we have investigated the variabilities of the Seyfert Galaxy 3C 120 over the period 1996-2008.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/652
- Title:
- Optical variability in NGC 7469
- Short Name:
- J/PAZh/21/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of three-color UBV observations of rapid variability in the nucleus of the Seyfert galaxy NGC 7469 carried out in 1990-1994 are presented. The observations have been carried out during 15 different nights using the 60- and 125-cm telescopes with time resolution of 6-8min (50 hours monitoring) with the aperture of 27.5". The mean errors of one measurement are 1.8, 1.2 and 1.4% for U, B and V. The data set length during one night is from 2 up to 5h. The different nights show the variations at different level: from weak, when the standard deviation during the night exceeds the error of one measurement only by 10-20%, up to strong ones, when the standard deviation exceeds the error of the measurement by factor two.
