- 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.
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- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/23
- Title:
- V-band photometric follow-up of RR Lyrae from SEKBO
- Short Name:
- J/ApJ/756/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the steepening of the power-law slope beyond the Galactocentric radius of R~45kpc in the RR Lyrae (RRL) space density distribution found by Keller et al. (2008, Cat. J/ApJ/678/851). They identified 2016 RRL candidates derived from the analysis of archival observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey. Our aim is to verify the completeness of RRLs and ultimately the space density distribution function given by Keller et al. We followed up on a subset of 137 candidates with a range of magnitudes (V~14-20) using the Faulkes Telescope (FT) database and confirmed 57 candidates as real RRLs. A cross-match between SEKBO RRL survey and Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL candidates in common. Applying the color selection criteria proposed by Ivezi\'c et al. (2005AJ....129.1096I) resulted in 193 likely RRLs. The completeness as a function of magnitude was calculated empirically from the combined set of SEKBO RRL candidates from current FT data, SDSS cross-matched data, and the Prior et al. catalog (2009, Cat. J/ApJ/691/306). This resulted in a spatial density distribution characterized by two power laws with a break radius R within a range between 45kpc and 50kpc, similar to the results of Keller et al. We find the power-law slopes for the inner halo as n_inner_=-2.78+/-0.02 and for the outer halo as n_outer_=-5.0+/-0.2.
- ID:
- ivo://CDS.VizieR/J/ApJ/846/115
- Title:
- V-band photometry and RVs of V482 Persei system
- Short Name:
- J/ApJ/846/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic and differential photometric observations of the A-type system V482 Per, which reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One binary has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e=0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e=0.85) with a period of 16.67yr. Radial velocities are measured for all components from our quadruple-lined spectra and are combined with the light curves and measurements of times of minimum light for the 2.4 day binary to solve for the elements of the inner and outer orbits simultaneously. The line-of-sight inclination angles of the three orbits are similar, suggesting they may be close to coplanar. The available observations appear to indicate that the 6 day binary experiences significant retrograde apsidal motion in the amount of about 60 deg per century. We derive absolute masses for the four stars good to better than 1.5%, along with radii with formal errors of 1.1% and 3.5% for the 2.4 day binary and ~9% for the 6 day binary. A comparison of these and other physical properties with current stellar evolution models gives excellent agreement for a metallicity of [Fe/H]=-0.15 and an age of 360Myr.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A48
- Title:
- V-band photometry of asteroids from ASAS-SN
- Short Name:
- J/A+A/654/A48
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present V-band photometry of the 20000 brightest asteroids using data from the All-Sky Automated Survey for Supernovae (ASAS-SN) between 2012 and 2018. We were able to apply the convex inversion method to more than 5000 asteroids with more than 60 good measurements in order to derive their sidereal rotation periods, spin axis orientations, and shape models. We derive unique spin state and shape solutions for 760 asteroids, including 163 new determinations. This corresponds to a success rate of about 15%, which is significantly higher than the success rate previously achieved using photometry from surveys. We derive the first sidereal rotation periods for additional 69 asteroids. We find good agreement in spin periods and pole orientations for objects with prior solutions. We obtain a statistical sample of asteroid physical properties that is sufficient for the detection of several previously known trends, such as the underrepresentation of slow rotators in current databases, and the anisotropic distribution of spin orientations driven by the nongravitational forces. We also investigate the dependence of spin orientations on the rotation period. Since 2018, ASAS-SNhas been observing the sky with higher cadence and a deeper limiting magnitude, which will lead to many more new solutions in just a few years.
