- 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.
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Search Results
- 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.
- 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.
- 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.
20545. 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A170
- Title:
- V-band differential photometry for V889 Her
- Short Name:
- J/A+A/622/A170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. This gives crucial information of the underlying dynamo process. Comparisons with the solar cycle enable us to infer knowledge about how the solar dynamo has evolved during the Sun's lifetime. Here we study the correlation between photometric brightness variations, spottedness and mean temperature in V889 Her, a young solar analogue. Our data covers 18 years of spectroscopic and 25 years of photometric observations. We use Doppler imaging to derive temperature maps from high-resolution spectra. We use the Continuous Period Search method to retrieve mean V-magnitudes from photometric data. Our Doppler imaging maps show a persistent polar spot structure varying in strength. This structure is centered slightly off the rotational pole. The mean temperature derived from the maps shows an overall decreasing trend, as does the photometric mean brightness, until it reaches its minimum around 2017. The filling factor of cool spots, however, shows only a weak tendency to anti-correlate with the decreasing mean brightness. We interpret V889 Her to have entered into a grand maximum in its activity. The clear relation between the mean temperature of the Doppler imaging surface maps and the mean magnitude supports the reliability of the Doppler images. The lack of correlation between the mean magnitude and the spottedness may indicate that bright features in the Doppler images are real.
- ID:
- ivo://CDS.VizieR/J/AJ/159/121
- Title:
- V-band light curve & RVs of the Cepheid V473Lyr
- Short Name:
- J/AJ/159/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V473Lyr is a classical Cepheid that is unique in having substantial amplitude variations with a period of approximately 3.3yr, thought to be similar to the Blazhko variations in RR Lyrae stars. We obtained an X-ray Multi-Mirror Mission (XMM)-Newton observation of this star to follow up a previous detection in X-rays. Rather than the X-ray burst and rapid decline near maximum radius seen in {delta}Cephei itself, the X-ray flux in V473Lyr remained constant for a third of the pulsation cycle covered by the observation. Thus the X-rays are probably not produced by the changes around the pulsation cycle. The X-ray spectrum is soft (kT=0.6keV), with X-ray properties consistent with a young low-mass companion. Previously there was no evidence of a companion in radial velocities or in Gaia and Hipparcos proper motions. While this rules out companions that are very close or very distant, a binary companion at a separation between 30 and 300au is possible. This is an example of an X-ray observation revealing evidence of a low-mass companion, which is important in completing the mass ratio statistics of binary Cepheids. Furthermore, the detection of a young X-ray bright companion is a further indication that the Cepheid (primary) is a Population I star, even though its pulsation behavior differs from other classical Cepheids.
- ID:
- ivo://CDS.VizieR/J/AcA/63/91
- Title:
- V-band light curves of variables in M80
- Short Name:
- J/AcA/63/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for variable stars in the globular cluster M 80. Application of the image subtraction method to the ground-based times-series of CCD frames resulted in finding nine new RR Lyr stars, six of the RRc and three of the RRab type, and four SX Phe variables.
