- ID:
- ivo://CDS.VizieR/J/ApJS/190/166
- Title:
- Optical catalog of AKARI NEP-wide survey
- Short Name:
- J/ApJS/190/166
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the source catalog and the properties of the B-, R-, and I-band images obtained to support the AKARI North Ecliptic Pole Wide (NEP-Wide) survey. The NEP-Wide is an AKARI infrared imaging survey of the north ecliptic pole covering a 5.8deg^2^ area over 2.5-6um wavelengths. The optical imaging data were obtained at the Maidanak Observatory in Uzbekistan using the Seoul National University 4kx4k Camera on the 1.5m telescope. These images cover 4.9deg^2^ where no deep optical imaging data are available. Our B-, R-, and I-band data reach the depths of ~23.4, ~23.1, and ~22.3mag(AB) at 5{sigma}, respectively. The source catalog contains 96460 objects in the R band, and the astrometric accuracy is about 0.15" at 1{sigma} in each RA and DEC direction. These photometric data will be useful for many studies including identification of optical counterparts of the infrared sources detected by AKARI, analysis of their spectral energy distributions from optical through infrared, and the selection of interesting objects to understand the obscured galaxy evolution.
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- ID:
- ivo://CDS.VizieR/J/ApJS/214/10
- Title:
- Optical counterparts of Chandra GBS sources
- Short Name:
- J/ApJS/214/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ~2hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray sources have at least one potential optical counterpart. Twenty-seven percent of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and discuss the characteristics of the variable population.
- ID:
- ivo://CDS.VizieR/J/ApJ/876/115
- Title:
- Optical follow-up of ASAS-SN M dwarf flares
- Short Name:
- J/ApJ/876/115
- Date:
- 18 Jan 2022 15:06:46
- Publisher:
- CDS
- Description:
- The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g~18mag. Over the course of its first 4yr of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified T Tauri star, a young star with outbursts, and two objects too faint to confirm. A detailed examination of the 49 flare star light curves revealed an additional six flares on five stars, resulting in a total of 55 flares on 49 objects ranging in V-band contrast from {Delta}V=-1 to -10.2mag. Using an empirical flare model to estimate the unobserved portions of the flare light curve, we obtain lower limits on the V-band energy emitted during each flare, spanning log(E_V_/erg)=32-35, which are among the most energetic flares detected on M dwarfs. The ASAS-SN M dwarf flare stars show a higher fraction of H{alpha} emission, as well as stronger H{alpha} emission, compared to M dwarfs selected without reference to activity, consistent with belonging to a population of more magnetically active stars. We also examined the distribution of tangential velocities, finding that the ASAS-SN flaring M dwarfs are likely to be members of the thin disk and are neither particularly young nor old.
- ID:
- ivo://CDS.VizieR/J/MNRAS/238/1171
- Title:
- Optical/IR observ. of Radio Galaxies and QSOs
- Short Name:
- J/MNRAS/238/1171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog reports on an extensive optical and infrared study of the 178 radio sources in the Parkes Selected Regions (S > 100 mJy at 2.7 GHz). CCD observations have resulted in the essential completion (95 percent) of optical identifications and have provided B and R photometry. In addition, K photometry has been completed for four of the six selected regions.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A90
- Title:
- Optically bright post-AGB population of LMC
- Short Name:
- J/A+A/530/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a catalogue of the optically bright post-AGB stars in the LMC. The sample forms an ideal testbed for stellar evolution theory predictions of the final phase of low- and intermediate-mass stars, because the distance and hence luminosity and also the current and initial mass of these objects is well constrained.
- ID:
- ivo://CDS.VizieR/J/other/JAD/24.3
- Title:
- Optically Variable Quasars in AllWISE/PS1
- Short Name:
- J/other/JAD/24.3
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- This catalog presents a sample of 229236 optically variable quasar candidates identified in the AllWISE and Pan-STARRS1 data releases at 2-sigma and 3-sigma variability levels. Mid-IR bands (3.4, 4.6, 12 and 22um) are selected from the AllWISE data release, and 5 optical bands (grizy) are from Pan-STARRS1. 127350 quasars are found to be variable at the 3-sigma level.
- ID:
- ivo://CDS.VizieR/J/A+A/431/779
- Title:
- Optical/near-IR atlas of OH/IR stars
- Short Name:
- J/A+A/431/779
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present optical and near-infrared finding charts, accurate astrometry (~1") and single-epoch near-infrared photometry for 371 IRAS sources, 96% of those included in the so-called "Arecibo sample of OH/IR stars" (Eder et al., 1988ApJS...66..183E; Lewis et al., 1990ApJ...362..634L; Chengalur et al., 1993, Cat. <J/ApJS/89/189>). The main photometric properties of the stars in the sample are presented and discussed as well as the problems found during the process of identification of the optical/near-infrared counterparts. In addition, we also identify suitable reference stars in each field to be used for differential photometry purposes in the future.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A60
- Title:
- Optical-NIR catalog of AKARI NEP Deep Field
- Short Name:
- J/A+A/566/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an 8-band (u*, g', r', i', z', Y, J, Ks) optical to near-infrared deep photometric catalogue based on the observations made with MegaCam and WIRCam at CFHT, and compute photometric redshifts, zph in the North Ecliptic Pole (NEP) region, where AKARI infrared satellite carried out deep survey at near to mid infrared wavelength. We designed the catalogue to include sources detected in z' band with counterparts in at least one of the other bands, and found 85797 sources in the NEP field. Comparing with galaxy spectroscopic redshifts, photometric redshift dispersion {sigma}({Delta}z/(1+z)) is 0.032 and catastrophic failure rate {Delta}z/(1+z)>0.15 is 5.8% at z<1. Our redshifts are highly accurate with z'<22 at zph<2.5 and for fainter sources with z'<24 at z<1.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/79
- Title:
- Optical photometry in 3 Local Group dwarf galaxies
- Short Name:
- J/ApJ/756/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep wide-field photometry of three recently discovered faint Milky Way (MW) satellites: Leo V, Pisces II, and Canes Venatici II. Our main goals are to study the structure and star formation history of these dwarfs; we also search for signs of tidal disturbance. The three satellites have similar half-light radii (~60-90pc) but a wide range of ellipticities. Both Leo V and CVn II show hints of stream-like overdensities at large radii. An analysis of the satellite color-magnitude diagrams shows that all three objects are old (>10Gyr) and metal-poor ([Fe/H]~-2), though neither the models nor the data have sufficient precision to assess when the satellites formed with respect to cosmic reionization. The lack of an observed younger stellar population (<~10Gyr) possibly sets them apart from the other satellites at Galactocentric distances >~150kpc. We present a new compilation of structural data for all MW satellite galaxies and use it to compare the properties of classical dwarfs to the ultra-faints. The ellipticity distribution of the two groups is consistent at the ~2{sigma} level. However, the faintest satellites tend to be more aligned toward the Galactic Center, and those satellites with the highest ellipticity (>~0.4) have orientations ({Delta}{theta}_GC_) in the range 20{deg}<~{Delta}{theta}_GC_<~40{deg}. This latter observation is in rough agreement with predictions from simulations of dwarf galaxies that have lost a significant fraction of their dark matter halos and are being tidally stripped.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/108
- Title:
- Optical photometry of 4 millisecond pulsars
- Short Name:
- J/ApJ/769/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified {gamma}-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in compact binaries with low-mass companions. These systems often show eclipses of the pulsar signal and are commonly known as black widows and redbacks because the pulsar is gradually destroying its companion. In this paper, we report on the optical discovery of four strongly irradiated millisecond pulsar companions. All four sources show modulations of their color and luminosity at the known orbital periods from radio timing. Light curve modeling of our exploratory data shows that the equilibrium temperature reached on the companion's dayside with respect to their nightside is consistent with about 10%-30% of the available spin-down energy from the pulsar being reprocessed to increase the companion's dayside temperature. This value compares well with the range observed in other irradiated pulsar binaries and offers insights about the energetics of the pulsar wind and the production of {gamma}-ray emission. In addition, this provides a simple way of estimating the brightness of irradiated pulsar companions given the pulsar spin-down luminosity. Our analysis also suggests that two of the four new irradiated pulsar companions are only partially filling their Roche lobe. Some of these sources are relatively bright and represent good targets for spectroscopic follow-up.
