Rapid light variation of Be star LQ And and EM Cep.
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Star (game theory)
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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 5 mag (R). In previous studies, V350 Cep was considered to be a potential FUor or EXor eruptive variable. Our data suggest that during the period of observations the star maintains its maximum brightness with low amplitude photometric variations. Our conclusion is that V350 Cep was probably an intermediate object between FUors and EXors, similar to V1647 Ori.
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Abstract Results from UBVRI photometric observations of the pre-main sequence star GM Cep obtained in the period 2011 April–2014 August are reported in the paper. Presented data are a continuation of our photometric monitoring of the star started in 2008. GM Cep is located in the field of the young open cluster Trumpler 37 and over the past years it has been an object of intense photometric and spectral studies. The star shows a strong photometric variability interpreted as a possible outburst from EXor type in previous studies. Our photometric data for a period of over six years show a large amplitude variability (Δ V ~ 2.3 mag) and several deep minimums in brightness are observed. The analysis of the collected multicolour photometric data show the typical of UX Ori variables a colour reversal during the minimums in brightness. The observed decreases in brightness have a different shape, and evidences of periodicity are not detected. At the same time, high amplitude rapid variations in brightness typical for the classical T Tauri stars also present on the light curve of GM Cep. The spectrum of GM Cep shows the typical of classical T Tauri stars wide Hα emission line and absorption lines of some metals. We calculate the outer radius of the Hα emitting region as 10.4 ± 0.5 R ⊙ and the accretion rate as 1.8 × 10 − 7 M ⊙ yr − 1 .
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Variable star
BETA (programming language)
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We report on the progress of our ongoing photometric monitoring program of spotted late-type stars with automatic photoelectric telescopes (APTs) on Mt. Hopkins in Arizona and on Mt. Etna in Sicily. We present 9 250 differential UBV and/or observations for altogether 23 chromospherically active stars, singles and binaries, pre main sequence and post main sequence, taken between 1991 and 1996. The variability mechanism of our target stars is mostly rotational modulation by an asymmetrically spotted stellar surface. Therefore, precise rotational periods and their seasonal variations are determined using baselines between 3 years for HD 129333 to 34 years for V410 Tauri. We report the largest V light-curve amplitude of any spotted star observed to date: for V410 Tau in 1994–95. Long-term variations of the overall light levels of our target stars are sometimes of similar amplitude as the rotational modulation itself and are most likely caused by an analog of the solar 11-year spot cycle but mostly without a well-defined periodicity. For some of our target stars (HD 12545, HD 17433, EI Eri, V410 Tau, LQ Hya, and HD 106225) we estimate a probable cycle period. A complete light curve of the semi-regular S-type giant HR Pegasii is presented. All data are available via the WorldWideWeb.
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Differential UBV observations of Aur and 31 Cyg, 28 of the former and 36 of the latter, were obtained shortly before and during their recent 1971-72 eclipses. Key words: photometry - eclipsing binaries
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New light curves obtained in UBV and R are presented for the short-period RS CVn-like binary WY Cancri. The system exhibits a distorted light curve at phases near second quadrature, and on one night excess light was seen at these phases. A light-curve-synthesis solution yields parameters that generally agree with the earlier transit model of Awadella and Budding (1979), although the derived temperature of the secondary is higher and its limb darkening lower. The recent observations fail to indicate any period change.
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We present a large set of new UBV and JHKL measurements on the eclipsing symbiotic nova AS 296 = FG Ser covering the period 1992-1994. The new data extend our older 1988-1991 observations and provide a complete multiband monitoring of the outburst evolution since its onset in early June 1988. The general trend of the outburst evolution is confirmed, with a series of multiple maxima superimposed onto a slow decrease in the mean brightness. A total eclipse of the erupting White Dwarf (WD)(the third one since the onset of the outburst), which was expected to take place in May-June 1993, has been observed as predicted. New infrared photometry confirms that the M5 3 component has been unaffected by the outburst. The cool giant appears well inside its Roche lobe. No dust or circumstellar nebular regions formed as a consequence of the outburst. The presence of unevenly spaced multiple maxima of large amplitude makes impossible to predict future behavior and total duration of the outburst. Photometric variations outside eclipse are not correlated with the orbital phase.
Dwarf nova
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