- 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).
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/415/283
- Title:
- BV light curves of NN Vir
- Short Name:
- J/A+A/415/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric BV light curves of the recently discovered eclipsing binary NN Vir were studied for the first time to derive the physical parameters of the system. The light curves were obtained at the Ankara University Observatory during three nights in May, 2002. The solutions made by using Djurasevic's inverse problem method describe the NN Vir system as a high overcontact configuration (f_over_~58%) with a relatively small temperature differences between the components ({Delta}T=T_h_-T_c_~160K). These solutions suggest a significant mass and energy transfer from the more massive primary onto the less massive secondary. The hot area on the less massive star, near the neck region, can be taken as a consequence of this mass and energy exchange between the components through the connecting neck of the common envelope.
- ID:
- ivo://CDS.VizieR/J/AJ/139/2014
- Title:
- BV light curves of 11 RR Lyrae
- Short Name:
- J/AJ/139/2014
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is not easy to identify and classify low-amplitude variables, but it is important that the classification is done correctly. We use photometry and spectroscopy to classify low-amplitude variables in a 246deg^2^ part of the Akerlof et al. (2000, Cat. J/AJ/119/1901) field. Akerlof and Collaborators found that 38% of the RR Lyrae stars in their 2000deg^2^ test field were RR1 (type c). This suggests that these RR Lyrae stars belong to an Oosterhoff Type II population, while their period distribution is primarily Oosterhoff Type I. Our observations support their RR0 (type ab) classifications; however, six of the seven stars that they classified as RR1 (type c) are eclipsing binaries. Our classifications are supported by spectroscopic metallicities, line-broadening, and Galactic rotation measurements. Our 246deg^2^ field contains 16 RR Lyrae stars that are brighter than m_R_=14.5; only four of these are RR1 (type c). This corresponds to an Oosterhoff Type I population in agreement with the period distribution.
- ID:
- ivo://CDS.VizieR/J/AJ/144/136
- Title:
- BV light curves of the Algol-type binary V1241 Tauri
- Short Name:
- J/AJ/144/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometry for the eclipsing binary V1241 Tau, which was obtained on six nights between 2011 December and 2012 January using the 85cm telescope at the Xinglong station of the National Astronomical Observatories of China. By using the updated Wilson-Devinney code, photometric models with third lights were deduced from two sets of light curves. The result implies that V1241 Tau is an Algol-type near-contact binary (NCB), whose mass ratio and filling-out of the primary are q=0.545(+/-0.003) and f_1_=82.4% (+/-0.2%), respectively. Based on all available times of minimum light spanning over 80yr, the O-C curve of V1241 Tau appears to show a quasi-sinusoidal oscillation, i.e., a light-time orbit. The modulated period and amplitude are P_mod_=47.4(+/-1.7)yr and A=0.0087(+/-0.0005)days, respectively. This kind of period variation may be more likely attributed to the light-time effect via a presence of an unseen third body. From an analysis of 23 Algol-type NCBs with EB-type light curves, we determine that the fill-out for the primary f_1_ will increase as the orbital period P decreases. With angular momentum loss, the orbit of the binary will shrink, which causes f_1_ to increase. The primary component finally fills its Roche lobe, and the binary evolves into contact configuration. Therefore, this kind of Algol-type NCB with EB-type light curves, such as V1241 Tau, may be a progenitor of the A-type W UMa binary.
- ID:
- ivo://CDS.VizieR/J/A+A/383/197
- Title:
- BV light curves of V511 Lyr in 1994-1996
- Short Name:
- J/A+A/383/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our time series analysis of sixteen BV light curves of the chromospherically active binary V511 Lyr confirmed the 2.7days rotation period uniquely. The seasonal periodicity changes of 3.8% indicated the presence of detectable surface differential rotation. The significant 2.67455days periodicity in the light curve minimum epochs suggested that the strongest starspot formation in V511 Lyr was concentrated on one stable active longitude. The differential BV photometry of V511 Lyr was made between May 1994 and June 1996 with the Vanderbilt-Tennessee State 0.4m Automated Photoelectric Telescope (APT). The comparison and check stars were HDE 337663 (C1) and HD 179422 (C2).
- ID:
- ivo://CDS.VizieR/J/A+A/418/249
- Title:
- BV light curves of WX Eridani
- Short Name:
- J/A+A/418/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- WX Eri is an eclipsing binary system for which one component was reported to show Delta Scuti type pulsations with periods close to integer fractions of the orbital period. This makes it an interesting candidate for investigating the interaction between binarity and pulsation and a potential new member of the recently defined group of mass-accreting pulsating components (gainers) in semi-detached Algol binaries called 'oscillating EA' stars. We present new photometric time-series observations of this star. The Wilson-Devinney code was applied to find the best fitting model for the eclipsing binary's light curve. The aim of the observations was to investigate the short-period Delta Scuti type pulsations of WX Eri. However, no evidence for the presence of such oscillations was found in our data.
- ID:
- ivo://CDS.VizieR/J/other/PASA/23.154
- Title:
- BV light curves of XY Leo, EE Cet, AQ Psc
- Short Name:
- J/other/PASA/23.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New photoelectric BV light curves of three close eclipsing binaries XY Leo, EE Cet and AQ Psc were observed at the Rozhen National Astronomical Observatory, Bulgaria in the period October 2004 - February 2005, by using the 0.6-m Cassegrain telescope, equipped with an UBV, single-channel, photon-counting, computer controlled photometer. Integration time of 10 seconds was chosen.
- ID:
- ivo://CDS.VizieR/J/A+AS/105/47
- Title:
- B,V photoelectric obs. of V505 Sgr
- Short Name:
- J/A+AS/105/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
