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- ID:
- ivo://CDS.VizieR/J/A+A/483/263
- Title:
- BV light curve of V570 Per
- Short Name:
- J/A+A/483/263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per are derived using Asiago Echelle high-resolution and high S/N spectroscopy, and B, V photo-electric photometry. Effective temperatures, gravities, rotational velocities, and metallicities of both components are also obtained from atmospheric chi^2^ analysis. The observed properties of V570 Per components are compared to available families of stellar evolutionary tracks, in particular to BaSTI models computed on purpose for exactly the observed masses and varied chemical compositions.
- ID:
- ivo://CDS.VizieR/J/A+A/452/959
- Title:
- BV light curve of V781 Tau
- Short Name:
- J/A+A/452/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze light curves of the W UMa type eclipsing binary V781 Tauri from three epochs and radial velocity curves from two epochs simultaneously, including previously unpublished B and V data. The overall time span is from 1983 to 2000 and the solution is done coherently in time (not phase) with five light curves and two sets of primary and secondary velocity curves. Minor systematic differences among the individual light curves are not large enough to undermine the value of a coherent solution that represents 18 years of observations. Times of minima confirm a period of 0.34491d and the general solution finds a small period change, dP/P, of (5.08+/-04)*10^-11^ that represents recent behavior. The eclipse timings cover the last half-century and find dP/P about four times smaller, corresponding to a period change time scale, P/(dP/dt) of about 6 million years. The system is over-contact with a filling factor of 0.205. The solution produces a temperature difference of about 260K between the components, an inclination of 65.9{deg}, and a mass ratio M_2_/M_1_=2.47. Separate solutions of the several light curves that incorporate dark spots find parameters that differ little from curve to curve. Absolute masses, luminosities, radii and the distance are derived, with luminosities and distance based on star 1 being of type G0V. The orbital angular momentum is compared with those of other W UMa type binaries and is normal. The star to star mass flow that one can infer from dP/dt is opposite to that expected from TRO (Thermal Relaxation Oscillator) theory, but pertains to a time span that is very short compared to the time scale of TRO oscillations.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/44
- Title:
- BV light curves of 33 ASAS-3 Cepheids
- Short Name:
- J/PAZh/35/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cepheids, the principal distance indicators, point to the existence of two inner Galactic spiral arms in the immediate solar neighborhood (within 5kpc). However, the available Cepheids are clearly insufficient for a detailed study of the structure of these arms. Fortunately, southern-sky monitoring (the ASAS project) has led to the discovery of many new variable stars, more than one thousand of which have been identified as possible Cepheids. To improve the classification and to construct reliable light curves for new Cepheids, we have begun their regular photometric observations. Here, we present the first results: 1192 photoelectric BVIc observations were performed for 33 classicalCepheidswith the 76-cm telescope of the South-African Astronomical Observatory (SAAO, the South-African Republic) from December 2006 to January 2008.We provide tables of observations and V light and B-V and V-Ic color curves. The new observations together with ASAS-3 data have been used to improve the elements of the light variations.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/115
- Title:
- BV light curves of AU Ser
- Short Name:
- J/A+AS/131/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the Table 1 shown are the Heliocentric Julian Days at the start and at the end of the observation runs and the numbers of the observations for each color. Since the observations in 1991 have been published in Li et al. (1992IBVS.3802....1L), only those in 1992 and 1995 are listed in Table 2a and 2b for yellow and blue light respectively, where the Heliocentric Julian Days and the magnitude differences(the variable minus the comparison) are given. The normal points producing the light curves in Fig. 2 can found in Table 3 through 5.
- ID:
- ivo://CDS.VizieR/J/AJ/134/642
- Title:
- BV light curves of BB Pegasi
- Short Name:
- J/AJ/134/642
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based photometry of the low-temperature contact binary BB Peg. We collected all the times of mid-eclipse available in the literature and combined them with those obtained in this study.
- ID:
- ivo://CDS.VizieR/J/AJ/141/195
- Title:
- BV light curves of FT Ori
- Short Name:
- J/AJ/141/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate absolute properties are determined for the first time for the 3.15 day period eccentric eclipsing binary star FT Ori based on new absolute photometry, five differential light curves, and a radial velocity curve. The stars appear to be normal for their spectral types, A0+A2. The orbit is highly eccentric (e=0.409) and shows apsidal motion with a period of 536-years. The absolute properties and the degree of central mass concentration of the stars are consistent with current theoretical models at an age of 190Myr.
- ID:
- ivo://CDS.VizieR/J/ApJ/647/1375
- Title:
- BV light curves of {gamma} Cas
- Short Name:
- J/ApJ/647/1375
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gamma Cas is an unusual classical Be star for which the optical-band and hard X-ray fluxes vary on a variety of timescales. We report results of a 9yr monitoring effort on this star with a robotic ground-based (APT) telescope in the B, V filter system, as well as simultaneous observations in 2004 November with this instrument and the RXTE. Our observations disclosed no correlated optical response to the rapid X-ray flares in this star, nor did the star show any sustained flux changes any time during two monitored nights in either wavelength regime. Consistent with an earlier study by Robinson et al. (2002ApJ...575..435R), optical light curves obtained in our new APT program revealed that Cas undergoes ~3% amplitude cycles with lengths of 50-91days. Our observations in 2004 showed a similar optical cycle. Over the 9 days we monitored the star with the RXTE, the X-ray flux varied in phase with its optical cycle and with an amplitude predicted from the data in Robinson et al. (2002ApJ...575..435R).
- ID:
- ivo://CDS.VizieR/J/ApJ/760/10
- Title:
- BV light curves of {gamma} Cas (1997-2011)
- Short Name:
- J/ApJ/760/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The B0.5 IVe star {gamma} Cas is of great interest because it is the prototype of a small group of classical Be stars having hard X-ray emission of unknown origin. We discuss results from ongoing B and V observations of the {gamma} Cas star-disk system acquired with an Automated Photometric Telescope during the observing seasons 1997-2011. In an earlier study, Smith, Henry, & Vishniac (Cat. J/ApJ/647/1375) showed that light variations in {gamma} Cas are dominated by a series of comparatively prominent cycles with amplitudes of 0.02-0.03mag and lengths of 2-3 months, superimposed on a 1.21 day periodic signal some five times smaller, which they attributed to rotation. The cycle lengths clustered around 70 days, with a total range of 50-91 days. Changes in both cycle length and amplitude were observed from year to year. These authors also found the V-band cycles to be 30%-40% larger than the B-band cycles. In the present study, we find continued evidence for these variability patterns and for the bimodal distribution of the {Delta}B/{Delta}V amplitude ratios in the long cycles. During the 2010 observing season, {gamma} Cas underwent a mass-loss event ("outburst"), as evidenced by the brightening and reddening seen in our new photometry. This episode coincided with a waning of the amplitude in the ongoing cycle. The Be outburst ended the following year, and the light-curve amplitude returned to pre-outburst levels. This behavior reinforces the interpretation that cycles arise from a global disk instability. We have determined a more precise value of the rotation period, 1.215811+/-0.000030 days, using the longer 15-season data set and combining solutions from the V and B light curves. Remarkably, we also find that both the amplitude and the asymmetry of the rotational waveform changed over the years. We review arguments for this modulation arising from transits of a surface magnetic disturbance. Finally, to a limit of 5 mmag, we find no evidence for any photometric variation corresponding to the {gamma} Cas binary period, 203.55 days, or to the first few harmonics.
- ID:
- ivo://CDS.VizieR/J/PASP/122/17
- Title:
- BV light curves of 2MASS J06451725+4122158
- Short Name:
- J/PASP/122/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of extensive time-series photometry of a new variable star, 2MASS 06451725+4122158, are presented. The B, V observations (over 4000 individual measurements) were made over 23 nights between 2006 and 2007. To investigate the star's physical characteristics additional Stroemgren photometric observations (uvbyHbeta) were made on another four nights in 2007 and 2009. Thirteen frequencies were found from a multifrequency analysis of the V and B photometry. All but two of the frequencies, 19.99716cycles/d (corresponding to the pulsation period of 0.0500071d) and 25.84662cycles/d (0.0386898d), have been identified as combination frequencies.
