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4471. VBLUW photometry of HD 93205
ID:
ivo://CDS.VizieR/J/A+A/397/921
Title:
VBLUW photometry of HD 93205
Short Name:
J/A+A/397/921
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 1982-1985 photometry (VBLUW system) of the O3V+O8V close binary HD 93205 has been rediscussed because of new insights into its true nature and orbital changes. By comparing this data set with the one obtained by Antokhina et al. (2000ApJ...529..463A) in 1993, and using the same ephemeris to construct the light curve in the phase diagram, the effect of the apsidal motion became obvious: a phase shift between the two light curves and a small change of the shape. A phase-locked light variation in the L passband (containing the higher Balmer lines) is clearly present in the 1982-1985 data set and is presumably due to absorption if the O8 star is seen through cooler inter-binary gas, e.g. the bow-shock between the two colliding winds.
4472. vby and BVI photometry of Omega Cen giants
ID:
ivo://CDS.VizieR/J/AJ/127/980
Title:
vby and BVI photometry of Omega Cen giants
Short Name:
J/AJ/127/980
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have obtained photometric observations in a 182arcmin^2 area, 25' to the north of the center of the globular cluster {omega} Centauri. The Stroemgren vby and broadband BI filters were used to obtain measurements for some 2500 stars. Preliminary examinations of parts of the data have been presented previously (Hughes & Wallerstein, 2000, Cat. <J/AJ/119/1225>; Hughes, Wallerstein, & van Leeuwen, 2002, in ASP Conf. Ser. 265, 73). Here we present the complete data set, study the giant branches, and use the B-I color index as a tool for assessing the ages of the populations within {omega} Cen.
4473. V392 Car light curve
ID:
ivo://CDS.VizieR/J/A+A/374/204
Title:
V392 Car light curve
Short Name:
J/A+A/374/204
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed study of an eclipsing binary which had been classified Ap SrCrEu (Hartoog, 1976ApJ...205..807H) before being known as a binary. Radial velocities measured at the times of both quadratures allow us to obtain precise masses for both components, while the light curve yields the radii. The following ephemeris and fundamental parameters of the system were obtained: HJD=(2447999.7656+/-0.0041) +(3.174990+/-0.000001) E, e=0.00, i=81.9+/-0.1{deg}, M_1_=1.90+/-0.02M_{sun}_, M_2_=1.85+/-0.02M_{sun}_, R_1_=1.63+/-0.03R_{sun}_, R_2_=1.60+/-0.03R_{sun}_, vsini_1_=27.6+/-3.5km/s, vsini_2_=23.6+/-3.6km/s. The projected rotational velocities were determined by fitting a synthetic spectrum convolved with a rotational profile to the observed spectrum. A comparison of the spectra of V392 Car and of the normal A star Cox 98, which has the same colour indices, shows that Sr is not overabundant and the metallicity of V392 Car is the same as that of the other cluster members. Therefore, V392 Car is a normal A2 star rather than an Ap star. The position of V392 Car in the HR diagram is entirely consistent with membership of the cluster NGC 2516. An independent estimate of the distance to this cluster was done using the parameters of the eclipsing system, and found to be in agreement with the Hipparcos one. A comparison of the parameters obtained from observations with predictions of internal structure models leads to a metallicity estimate [M/H]=0+/-0.10dex for NGC 2516. This estimate is completely independent of any spectroscopic or photometric method (except for the T_eff_ determination) but relies on stellar structure models.
4474. V823 Cas BV(RI)c differential photometry
ID:
ivo://CDS.VizieR/J/A+A/445/617
Title:
V823 Cas BV(RI)c differential photometry
Short Name:
J/A+A/445/617
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0+f2=2f1 resonance may act in triple mode pulsators.
4475. V523 Cas UBVR_C_I_C_ photometry
ID:
ivo://CDS.VizieR/J/AJ/120/1548
Title:
V523 Cas UBVR_C_I_C_ photometry
Short Name:
J/AJ/120/1548
Date:
21 Oct 2021
Publisher:
CDS
Description:
The cool, overcontact, close binary, V523 Cassiopeiae was observed with the 1 m reflector at the US Naval Observatory, Flagstaff Station. The photometry was very good, with a precision on the order of a few millimagnitudes, but not numerous enough for complete light-curve analyses (e.g., differential corrections). A conventional published synthesis has been found acceptable as a fiducial model, and most of the observational weight has been used to develop a spot model for the stars and to support the validity of theoretical limb-darkening coefficients. Both photospheres and chromospheres contribute to the model. This result indicates that multifilter measures of this and similarly cool binaries are necessary for fuller descriptions of stellar activity cycles. A number of newly determined times of minimum light solidify the published rate of period variability.
4476. V810 Cen Geneva photometry
ID:
ivo://CDS.VizieR/J/A+A/337/779
Title:
V810 Cen Geneva photometry
Short Name:
J/A+A/337/779
Date:
21 Oct 2021
Publisher:
CDS
Description:
The light curve of the yellow supergiant V810 Centauri in the Geneva photometric system has been analysed with Date Compensate Fourier Transform and Weighted Wavelet Z-transform. Two periods around 150 and 100 days dominate the frequency spectrum but variable amplitudes and other modes are required to fully reproduce whole data set.
4477. V977 Cep and V982 Cep long-term photometry
ID:
ivo://CDS.VizieR/J/other/RAA/17.20
Title:
V977 Cep and V982 Cep long-term photometry
Short Name:
J/other/RAA/17.2
Date:
21 Oct 2021
Publisher:
CDS
Description:
Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.
4478. V350 Cep UBVRI long-term photometry
ID:
ivo://CDS.VizieR/J/other/RAA/14.1264
Title:
V350 Cep UBVRI long-term photometry
Short Name:
J/other/RAA/14.1
Date:
21 Oct 2021
Publisher:
CDS
Description:
Results from UBVRI optical photometric observations of the pre-main sequence star V350 Cep during the period 2004-2014 are presented. The star was discovered in 1977 due to its remarkable increase in brightness by more than 5mag (R). In previous studies, V350 Cep is considered to be a potential FUor or EXor eruptive variable. Our data suggest that during the period of observations the star keeps its maximum brightness with low amplitude photometric variations. Our conclusion is that V350 Cep is probably an intermediate object between FUors and EXors, similar to V1647 Ori.
4479. V368 Cep UBVRI time series
ID:
ivo://CDS.VizieR/J/A+A/350/513
Title:
V368 Cep UBVRI time series
Short Name:
J/A+A/350/513
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our time series analysis of V368 Cep photometry ascertains the rotation period of 2.74d uniquely. The manifestations of starspot induced luminosity variations in this chromospherically active star include rapid light curve changes and differential rotation of about 3%. We conclude that the single rapidly rotating variable V368 Cep is a high inclination K1V post T Tauri star.
4480. V444 Cyg BV differential light curves
ID:
ivo://CDS.VizieR/J/AN/332/616
Title:
V444 Cyg BV differential light curves
Short Name:
J/AN/332/616
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometric and spectroscopic characteristics of the WN5+O6 binary system, V444 Cyg, were studied. The Wilson-Devinney (WD) analysis, using new BV observations carried out at the Ankara University Observatory, revealed the masses, radii, and temperatures of the components of the system as M_WR_=10.64M_{sun}_, M_O_=24.68M_{sun}_, R_WR_=7.19R_{sun}_, R_O_=6.85R_{sun}_, T_WR_=31000K, and T_O_=40000K, respectively. It was found that both components had a full spherical geometry, whereas the circumstellar envelope of the WR component had an asymmetric structure. The O-C analysis of the system revealed a period lengthening of 0.139+/-0.018s/yr, implying a mass loss rate of (6.76+/-0.39)x10^-6^M_{sun}/yr for the WR component. Moreover, 106 IUE-NEWSIPS spectra were obtained from NASA's IUE archive for line identification and determination of line profile variability with phase, wind velocities and variability in continuum fluxes. The integrated continuum flux level (between 1200-2000{AA}) showed a mild and regular increase from orbital phase 0.00 up to 0.50 and then a decrease in the same way back to phase 0.00. This is evaluated as the O component making a constant and regular contribution to the system's UV light as the dominant source. The CIV line, originating in the circumstellar envelope, had the highest velocity while N IV line, originating in deeper layers of the envelope, had the lowest velocity. The average radial velocity calculated by using the CIV line (wind velocity) was found as 2326km/s.