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23601. Variations of O-B stars in Mercator observations
ID:
ivo://CDS.VizieR/J/A+A/463/243
Title:
Variations of O-B stars in Mercator observations
Short Name:
J/A+A/463/243
Date:
21 Oct 2021
Publisher:
CDS
Description:
We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, beta Cep, and Maia stars after the analysis of their Hipparcos data. We analysed both the Hipparcos data and our new seven passband Geneva data collected for these stars during the first three years of scientific operations of the Mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality Mercator observations to improve their variability classification. We searched for frequencies by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. In total we detected 60 frequencies, among which 32 new ones. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid beta Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant stars. For the 27 confirmed variable stars in our sample, we give the values and the corresponding standard errors of the accepted frequencies, the amplitudes, the phases, the constant terms, and the residual standard deviations as found in the seven filters of the Geneva photometric system and in the Hp filter of the Hipparcos photometric system by fitting the data with a superposition of sinusoidal models with reference epoch HJD=2450000.
23602. Variations of RS CVn primaries. II. o Dra
ID:
ivo://CDS.VizieR/J/ApJ/809/159
Title:
Variations of RS CVn primaries. II. o Dra
Short Name:
J/ApJ/809/159
Date:
21 Oct 2021
Publisher:
CDS
Description:
To measure the stellar and orbital properties of the metal-poor RS CVn binary o Draconis (o Dra), we directly detect the companion using interferometric observations obtained with the Michigan InfraRed Combiner at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array. The H-band flux ratio between the primary and secondary stars is the highest confirmed flux ratio (370+/-40) observed with long-baseline optical interferometry. These detections are combined with radial velocity data of both the primary and secondary stars, including new data obtained with the Tillinghast Reflector Echelle Spectrograph on the Tillinghast Reflector at the Fred Lawrence Whipple Observatory and the 2m Tennessee State University Automated Spectroscopic Telescope at Fairborn Observatory. We determine an orbit from which we find model-independent masses and ages of the components (M_A_=1.35+/-0.05M_{sun}_, M_B_=0.99+/-0.02M_{sun}_, system age =3.0+-0.5Gyr). An average of a 23-year light curve of o Dra from the Tennessee State University Automated Photometric Telescope folded over the orbital period newly reveals eclipses and the quasi-sinusoidal signature of ellipsoidal variations. The modeled light curve for our system's stellar and orbital parameters confirm these ellipsoidal variations due to the primary star partially filling its Roche lobe potential, suggesting most of the photometric variations are not due to stellar activity (starspots). Measuring gravity darkening from the average light curve gives a best-fit of {beta}=0.07+/-0.03, a value consistent with conventional theory for convective envelope stars. The primary star also exhibits an anomalously short rotation period, which, when taken with other system parameters, suggests the star likely engulfed a low-mass companion that had recently spun-up the star.
23603. Variations of the fine-structure constant
ID:
ivo://CDS.VizieR/J/other/MmSAI/80.833
Title:
Variations of the fine-structure constant
Short Name:
J/other/MmSAI/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Keck telescope's High Resolution Spectrograph (HIRES) has previously provided evidence for a smaller fine-structure constant, {alpha}, compared to the current laboratory value, in a sample of 143 quasar absorption systems: {Delta}{alpha}/{alpha}=(-0.57+/-0.11)10^-5^. The analysis was based on a variety of metal-ion transitions which, if alpha varies, experience different relative velocity shifts. This result is yet to be robustly contradicted, or confirmed, by measurements on other telescopes and spectrographs; it remains crucial to do so.
23604. Variations on debris disks. II.
ID:
ivo://CDS.VizieR/J/ApJS/188/242
Title:
Variations on debris disks. II.
Short Name:
J/ApJS/188/242
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe comprehensive calculations of the formation of icy planets and debris disks at 30-150AU around 1-3M_{sun}_ stars. Disks composed of large, strong planetesimals produce more massive planets than disks composed of small, weak planetesimals. The maximum radius of icy planets ranges from ~1500km to 11500km. The formation rate of 1000km objects-"Plutos"-is a useful proxy for the efficiency of icy planet formation. Plutos form more efficiently in massive disks, in disks with small planetesimals, and in disks with a range of planetesimal sizes. Although Plutos form throughout massive disks, Pluto production is usually concentrated in the inner disk. Despite the large number of Plutos produced in many calculations, icy planet formation is inefficient. At the end of the main sequence lifetime of the central star, Plutos contain less than 10% of the initial mass in solid material. This conclusion is independent of the initial mass in the disk or the properties of the planetesimals. Debris disk formation coincides with the formation of planetary systems containing Plutos. As Plutos form, they stir leftover planetesimals to large velocities. A cascade of collisions then grinds the leftovers to dust, forming an observable debris disk. In disks with small (<~1-10km) planetesimals, collisional cascades produce luminous debris disks with maximum luminosity ~10-2 times the stellar luminosity. Disks with larger planetesimals produce debris disks with maximum luminosity ~5x10^-4^ (10km) to 5x10^-5^ (100km) times the stellar luminosity. Following peak luminosity, the evolution of the debris disk emission is roughly a power law, f{propto}t^-n^ with n~0.6-0.8. Observations of debris disks around A-type and G-type stars strongly favor models with small planetesimals. In these models, our predictions for the time evolution and detection frequency of debris disks agree with published observations. We suggest several critical observations that can test key features of our calculations.
23605. Varstrometry of SDSS quasars with Gaia DR2 data
ID:
ivo://CDS.VizieR/J/ApJ/888/73
Title:
Varstrometry of SDSS quasars with Gaia DR2 data
Short Name:
J/ApJ/888/73
Date:
18 Nov 2021 08:43:02
Publisher:
CDS
Description:
Gaia's precision astrometry allows systematic identification of optically selected subkiloparsec dual active galactic nuclei (AGNs), off-nucleus AGNs, and small-scale lensed quasars by "varstrometry"-where variability-induced astrometric jitter, i.e., temporal displacements of photocenter in unresolved sources, can be reasonably well detected or constrained. This approach extends systematic searches for small-scale (>=mas) dual and off-nucleus AGNs to the poorly explored regime between ~10pc and ~1kpc, with Gaia's full sky coverage and depth to G~21. We outline the general principles of this method and calculate the expected astrometric signals from the full time series of photocenter measurements and light curves. We demonstrate the feasibility of varstrometry by using Gaia DR2 data on a sample of variable pre-main-sequence stars with known close companions. We find that extended host galaxies have a significant impact on the accuracy of astrometric and photometric variability in Gaia DR2, a situation to be improved in future Gaia releases. Using spectroscopically confirmed Sloan Digital Sky Survey quasars, we present several examples of candidate subkiloparsec off-nucleus or dual AGNs selected from Gaia DR2. We discuss the merits and limitations of this method and a follow-up strategy for promising candidates. We highlight Gaia's potential of systematically discovering and characterizing the subkiloparsec off-nucleus and dual AGN population in the entire optical sky.
23606. VAST Survey. A-type stars multiplicity
ID:
ivo://CDS.VizieR/J/MNRAS/437/1216
Title:
VAST Survey. A-type stars multiplicity
Short Name:
J/MNRAS/437/1216
Date:
21 Oct 2021
Publisher:
CDS
Description:
With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D<=75pc) multiplicity survey of A-type stars, sensitive to companions beyond 30AU. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45000AU. A total of 137 stellar companions were resolved, including 64 new detections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of 387^+132^_-98_AU. Integrating the fit to the distribution over the 30 to 10000AU observed range, the companion star fraction for A-type stars is estimated as 33.8+/-2.6%. The mass ratio distribution of closer (<125AU) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9+/-7.0%. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of 56.4_-4.0_^+3.8^, 32.1_-3.5_^+3.9^, 9.0_-1.8_^+2.8^, 1.9_-0.6_^+1.8^ and 0.6_-0.2_^+1.4^ percent, respectively.
23607. Vatican AC Zone Data Reduced to ACRS
ID:
ivo://CDS.VizieR/I/226
Title:
Vatican AC Zone Data Reduced to ACRS
Short Name:
I/226
Date:
21 Oct 2021
Publisher:
CDS
Description:
The U.S. Naval Observatory is in the process of making new reductions of the Astrographic Catalogue (AC) using a modern reference system, the ACRS, which represents the system of the FK5. The data from the Vatican Zone, whose plates are centered between declinations +55 and +64 degrees (eq. 1900), have been analyzed for scale, rotation, tilt, coma, magnitude equation, radial distortion and distortions introduced by the use of reseaux in the Carte du Ciel program. The result is a positional catalog of over 256,000 stars on eq. J2000.0, epoch of observation. Additionally, all stars have been matched with the Tycho Input Catalog (revised); those numbers have been added for additional identification purposes.
23608. Vatican Emission-line stars
ID:
ivo://CDS.VizieR/III/256
Title:
Vatican Emission-line stars
Short Name:
III/256
Date:
21 Oct 2021
Publisher:
CDS
Description:
The survey represents a search for H{alpha} emission-line stars, and was conducted with a 12{deg} objective prism on the Vatican Schmidt telescope. The Vatican Emission Stars (VES) survey covers the galactic plane (|b|<=5{deg}) between galactic longitudes 58 and 174{deg}. The catalog was re-examined by B. Skiff (Lowell Observatory), and tne VES stars were cross-identified with modern surveys: GSC (Cat. I/255), Tycho-2 (I/256), 2MASS (II/246), IRAS point source catalog (II/125), MSX6C (V/114), CMC14 (I/304), GSC-2.3 (I/305), UCAC2 (I/289). Cross-identifications are also supplied with HD/BD/GCVS names, and with Dearborn catalog of red stars (II/68). Many of the stars in the first four papers are not early-type emission-line stars, but instead M giants, where the sharp TiO bandhead at 6544{AA} was mistaken for H-{alpha} emission on the objective-prism plates. Based on the revision of paper V and a later list prepared by Jack MacConnell, a column identifies the "non H-alpha" stars explicitly. The links with the Dearborn, IRAS, and MSX catalogues help identify the red stars. These and other identifications and comments are given in the remarks at the end of each line, or in longer notes in a separate file, indicated by an asterisk (*) next to the star number.
23609. V-band, 5100{AA} and broad emission LCs of Mrk 79
ID:
ivo://CDS.VizieR/J/ApJ/887/135
Title:
V-band, 5100{AA} and broad emission LCs of Mrk 79
Short Name:
J/ApJ/887/135
Date:
21 Oct 2021
Publisher:
CDS
Description:
We developed a spectroscopic monitoring project to investigate the kinematics of the broad-line region (BLR) in active galactic nuclei (AGNs) with ultrafast outflows (UFOs). Mrk 79 is a radio-quiet AGN with UFOs and warm absorbers and has been monitored by three reverberation mapping (RM) campaigns, but its BLR kinematics are not yet understood. In this paper, we report the results from a new RM campaign of Mrk 79, which was undertaken with the Lijiang 2.4m telescope. Mrk 79 appears to come out the faint state, with the mean flux approximately a magnitude fainter than the historical record. We successfully measured the lags of the broad emission lines including H{beta}{lambda}4861, H{gamma}{lambda}4340, HeII{lambda}4686, and HeI{lambda}5876 with respect to the varying AGN continuum. Based on the broad H{beta}{lambda}4861 line, we measured a black hole mass of M_{bullet}_=5.13_-1.55_^+1.57^x10^7^M_{sun}_, and an estimated accretion rate of dM/dt_{bullet}_=(0.05+/-0.02)L_Edd_c^-2^, indicating that Mrk 79 is a sub-Eddington accretor. We found that Mrk 79 deviates from the canonical Radius-Luminosity relationship. The marginal blueshift of the broad HeII{lambda}4686 line detected from the rms spectrum indicates outflow of high- ionization gas. The velocity-resolved lag profiles of the broad H{gamma}{lambda}4340, H{beta}{lambda}4861, and HeI{lambda}5876 lines show similar signatures such that the largest lag occurs in the red wing of the lines and then the lag decreases to both sides. These signatures may suggest that the BLR of Keplerian motion probably exists as outflow gas motion. All findings including UFOs, warm absorbers, and the kinematics of high- and low-ionization BLR, may provide indirect evidence that the BLR of Mrk 79 probably originates from a disk wind.
23610. V-band and H{beta} monitoring of Z299-15
ID:
ivo://CDS.VizieR/J/ApJ/732/121
Title:
V-band and H{beta} monitoring of Z299-15
Short Name:
J/ApJ/732/121
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Seyfert 1 galaxy Zw 229-015 is among the brightest active galaxies being monitored by the Kepler mission. In order to determine the black hole mass in Zw 229-015 from H{beta} reverberation mapping, we have carried out nightly observations with the Kast Spectrograph at the Lick 3m telescope during the dark runs from 2010 June through December, obtaining 54 spectroscopic observations in total. We have also obtained nightly V-band imaging with the Katzman Automatic Imaging Telescope at Lick Observatory and with the 0.9m telescope at the Brigham Young University West Mountain Observatory over the same period. We detect strong variability in the source, which exhibited more than a factor of two change in broad H{beta} flux. From cross-correlation measurements, we find that the H{beta} light curve has a rest-frame lag of 3.86^+0.69^_-0.90_ days with respect to the V-band continuum variations. We also measure reverberation lags for H{alpha} and H{gamma} and find an upper limit to the H{delta} lag. Combining the H{beta} lag measurement with a broad H{beta} width of {sigma}_line_=1590+/-47km/s measured from the rms variability spectrum, we obtain a virial estimate of M_BH_=1.00^+0.19^_-0.24_x10^7^M_{sun}_ for the black hole in Zw 229-015.

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