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791. BVRI light curves of GR Boo
ID:
ivo://CDS.VizieR/J/other/NewA/53.39
Title:
BVRI light curves of GR Boo
Short Name:
J/other/NewA/53.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present BVRI light curves with complete phase coverage for the short-period (p=0.377day) eclipsing binary star GR Boo. We carried out the observations using the SARA 90cm telescope located at Kitt Peak National Observatory. We obtained six new light curve minimum times. By fitting all of the available O-C minimum times, we obtained an updated ephemeris that shows the orbital period of GR Boo is decreasing at a rate of dP/dt=-2.36x10^-7^days/year. This decrease in its period can be explained by either mass transfer from the more massive component to the less massive one, or angular momentum exchange due to magnetic activities. We also obtained a set of revised orbital parameters using the Wilson & Devinney program. And finally, we concluded that GR Boo is a contact binary with a dark spot.
792. BVRI light curves of GSC2314-0530
ID:
ivo://CDS.VizieR/J/MNRAS/406/2559
Title:
BVRI light curves of GSC2314-0530
Short Name:
J/MNRAS/406/2559
Date:
21 Oct 2021
Publisher:
CDS
Description:
CD photometric observations in VRI colours and spectroscopic observations of the newly discovered eclipsing binary GSC 2314-0530 (NSVS 6550671) with dMe components and a very short period of P=0.192636d are presented. The simultaneous light-curve solution and radial velocity solution allow us to determine the global parameters of GSC 2314-0530: T1=3735K; T2=3106K; M1=0.51M_{sun}_; M2=0.26M_{sun}_; R1=0.55R_{sun}_; R2=0.29R_{sun}_; L1=0.053L_{sun}_; L2=0.007L_{sun}_; i=72.5{swg}; a=1.28R_{sun}_; d=59pc.
793. BVRI light curves of KIC 6382916
ID:
ivo://CDS.VizieR/J/MNRAS/433/394
Title:
BVRI light curves of KIC 6382916
Short Name:
J/MNRAS/433/394
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a multisite photometric campaign on the high-amplitude {delta} Scuti star KIC 6382916 in the Kepler field. The star was observed over a 85-d interval at five different sites in North America and Europe during 2011. Kepler photometry and ground-based multicolour light curves of KIC 6382916 are used to investigate the pulsational content and to identify the principal modes. High-dispersion spectroscopy was also obtained in order to derive the stellar parameters and projected rotational velocity. From an analysis of the Kepler time series, three independent frequencies and a few hundred combination frequencies are found. The light curve is dominated by two modes with frequencies f1=4.9107d^-1^ and f2=6.4314d^-1^. The third mode with f3=8.0350d^-1^ has a much lower amplitude. We attempt mode identification by examining the amplitude ratios and phase differences in different wavebands from multicolour photometry and comparing them to calculations for different spherical harmonic degree, l. We find that the theoretical models for f1 and f2 are in a best agreement with the observations and lead to value of l=1 modes, but the mode identification of f3 is uncertain due to its low amplitude. Non-adiabatic pulsation models show that frequencies below 6d^-1^ are stable, which means that the low frequency of f1 cannot be reproduced. This is a further confirmation that current models predict a narrower pulsation frequency range than actually observed.
794. BVRI light curves of KIC Cepheids
ID:
ivo://CDS.VizieR/J/MNRAS/413/2709
Title:
BVRI light curves of KIC Cepheids
Short Name:
J/MNRAS/413/2709
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch, 40 candidates were selected from previous surveys and data bases. The analysis of the first 322d of Kepler photometry, and recent ground-based follow-up multicolour photometry and spectroscopy allowed us to confirm that one of these stars, V1154 Cyg (KIC 7548061), is indeed a 4.9d Cepheid. Using the phase lag method, we show that this star pulsates in the fundamental mode. New radial velocity data are consistent with previous measurements, suggesting that a long-period binary component is unlikely. No evidence is seen in the ultraprecise, nearly uninterrupted Kepler photometry for non-radial or stochastically excited modes at the micromagnitude level. The other candidates are not Cepheids, but an interesting mix of possible spotted stars, eclipsing systems and flare stars.
795. BVRI light curves of KZ Pav
ID:
ivo://CDS.VizieR/J/MNRAS/407/497
Title:
BVRI light curves of KZ Pav
Short Name:
J/MNRAS/407/497
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from analysing new spectroscopic and photometric observations of the KZ Pav (IDS 20490-7048 A-BC) multiple system. High-resolution spectra were taken at the Mt John University Observatory in 2007 and 2008. Radial velocities for the close binary were determined from cross-correlation and spectral disentangling methods.
796. BVRI light curves of 3 massive binaries
ID:
ivo://CDS.VizieR/J/A+A/601/A133
Title:
BVRI light curves of 3 massive binaries
Short Name:
J/A+A/601/A133
Date:
21 Oct 2021
Publisher:
CDS
Description:
The role of mass and momentum exchanges in close massive binaries is very important in the subsequent evolution of the components. Such exchanges produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again. We investigated these effects for the close O-star binary LSS 3074 (O4f+O6-7:(f):), which is a good candidate for a past Roche lobe overflow (RLOF) episode because of its very short orbital period, P=2.185-days, and the luminosity classes of both components. We determined a new orbital solution for the system. We studied the photometric light curves to determine the inclination of the orbit and Roche lobe filling factors of both stars. Using phase-resolved spectroscopy, we performed the disentangling of the optical spectra of the two stars. We then analysed the reconstructed primary and secondary spectra with the CMFGEN model atmosphere code to determine stellar parameters, such as the effective temperatures and surface gravities, and to constrain the chemical composition of the components. We confirm the apparent low stellar masses and radii reported in previous studies. We also find a strong overabundance in nitrogen and a strong carbon and oxygen depletion in both primary and secondary atmospheres, together with a strong enrichment in helium of the primary star. We propose several possible evolutionary pathways through a RLOF process to explain the current parameters of the system. We confirm that the system is apparently in overcontact configuration and has lost a significant portion of its mass to its surroundings. We suggest that some of the discrepancies between the spectroscopic and photometric properties of LSS 3074 could stem from the impact of a strong radiation pressure of the primary.
797. BVRI light curves of NGC 247 Cepheids
ID:
ivo://CDS.VizieR/J/ApJ/694/1237
Title:
BVRI light curves of NGC 247 Cepheids
Short Name:
J/ApJ/694/1237
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report VRI CCD observations of nine Cepheids in the South Polar (Sculptor) Group spiral galaxy NGC 0247. Periods of these Cepheids range from 20 to 70 days. Over the past 20 years, the brightest Cepheid in our sample, NGC 0247:[MF09] C1, has decreased its period by 6%, faded by 0.8mag in the V band, and become bluer by 0.23mag in (V-I).
798. BVRI light curves of Nova V723 Cas
ID:
ivo://CDS.VizieR/J/MNRAS/454/123
Title:
BVRI light curves of Nova V723 Cas
Short Name:
J/MNRAS/454/123
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical spectroscopy collected at seven epochs and BVRcIc photometry obtained at 1227 epochs of nova V723 Cas, covering the time interval between 2007 and 2015. The mean magnitude during this period, stable at ~3mag brighter than in quiescence, and the continuous presence of strong [FeX] and other high-ionization emission lines, indicates that the nuclear burning at the surface of the white dwarf is continuing 20-years past the initial outburst. The light curve shows a large amplitude (2mag) orbital modulation, which is governed by the visibility of the irradiated side of the secondary star. Our observations do not confirm the reported increase with time of the orbital period of V723 Cas, a period of P=16.638383+/-0.000025h satisfying equally well all available observations in all bands. Our observations also do not confirm the presence of an additional periodicity around P=15.2397h from which V723 Cas was classified as an intermediate-polar system.
799. BVRI light curves of PG 1553+113
ID:
ivo://CDS.VizieR/J/A+A/645/A137
Title:
BVRI light curves of PG 1553+113
Short Name:
J/A+A/645/A137
Date:
21 Oct 2021
Publisher:
CDS
Description:
The TeV BL Lac object PG 1553+113 is one of the primary candidates for a binary supermassive black hole system. We study the flux and spectral variability of PG 1553+113 on intra-night to long-term timescales using (i) BVRI data collected over 76 nights from January 2016 to August 2019 involving nine optical telescopes and (ii) historical VR data (including ours) obtained for the period from 2005 to 2019. We analysed the light curves using various statistical tests, fitting and cross-correlation techniques, and methods for the search for periodicity. We examined the colour-magnitude diagrams before and after the corresponding light curves were corrected for the long-term variations. Our intra-night monitoring, supplemented with literature data, result in a low duty cycle of ~(10-17)%. In April 2019, we recorded a flare, which marks the brightest state of PG 1553+113 for the period from 2005 to 2019: R~13.2mag. This flare is found to show a clockwise spectral hysteresis loop on its VR colour-magnitude diagram and a time lag in the sense that the V-band variations lead the R-band ones. We obtain estimates of the radius, the magnetic field strength, and the electron energy that characterize the emission region related to the flare. We find a median period of (2.21+/-0.04) years using the historical light curves. In addition, we detect a secondary period of about 210 days using the historical light curves corrected for the long-term variations. We briefly discuss the possible origin of this period.
800. BVRI light curves of S5 0716+714
ID:
ivo://CDS.VizieR/J/AJ/136/1846
Title:
BVRI light curves of S5 0716+714
Short Name:
J/AJ/136/1846
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical photometry (B, V, R, and I) of the BL Lac object S5 0716+714 (z>0.3), which were observed with the 1m telescope at Yunnan Astronomical Observatory and the 1.56m telescope at Shanghai Astronomical Observatory from 2001 February to 2006 April.