Statistics of BY Draconis variables

Alekseev, I. Yu.

doi:10.1134/1.1312966

Cited by 14 publications

(11 citation statements)

References 15 publications

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“…In another case, the cataclysmic variable PX And, the period we detect is the disc precession period rather than the binary orbital period of 0.14635d. Brancewicz & Dworak (1980) J225154.86+314457.5 1RXS J225153.6+314513 1.6404 11.12 13.22 11.13 GT Peg BY Dra/UV Cet 1.641 Alekseev (1998) J231653.34+254310.1 1RXS J231653.6+254312 11.6361 9.54 9.12 7.55 EZ Peg RS CVn 11.766 Koen & Eyer (2002) The remaining 360 objects comprise newly identified periodic variable stars which are also X-ray sources. Their details are listed in Table 2 and their SuperWASP lightcurves and power spectra are also shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

New periodic variable stars coincident withROSATsources discovered using SuperWASP

Norton¹,

Wheatley

West

et al. 2007

A&A

116

110

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We present optical lightcurves of 428 periodic variable stars coincident with ROSAT X-ray sources, detected using the first run of the SuperWASP photometric survey. Only 68 of these were previously recognised as periodic variables. A further 30 of these objects are previously known pre-main sequence stars, for which we detect a modulation period for the first time. Amongst the newly identified periodic variables, many appear to be close eclipsing binaries, their X-ray emission is presumably the result of RS CVn type behaviour. Others are probably BY Dra stars, pre-main sequence stars and other rapid rotators displaying enhanced coronal activity. A number of previously catalogued pulsating variables (RR Lyr stars and Cepheids) coincident with X-ray sources are also seen, but we show that these are likely to be misclassifications. We identify four objects which are probable low mass eclipsing binary stars, based on their very red colour and light curve morphology.

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Section: Resultsmentioning

confidence: 99%

New periodic variable stars coincident withROSATsources discovered using SuperWASP

Norton¹,

Wheatley

West

et al. 2007

A&A

116

110

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“…In the field, BY Dra stars are chromospherically active MS stars (dK to dM) in binary systems (Alekseev 2000). Their characteristics of weak Ha emission and variability typically on the order of days suggest chromospheric activity created by fast rotation.…”

Section: Introductionmentioning

confidence: 99%

Helium White Dwarfs and BY Draconis Binaries in the Globular Cluster NGC 6397

Taylor

Grindlay

Edmonds

et al. 2001

The Astrophysical Journal

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We examine 15 orbits of Hubble Space Telescope observations of the nearby post-core-collapsed globular cluster NGC 6397 using narrowband photometry in Ha with broadband photometry in V, R, and I. We recover the candidate helium white dwarfs (He WDs) recently discovered by Cool et al., of which one was examined spectroscopically by Edmonds et al., along with a sequence of these objects extending down to the magnitude limit of the survey. We also find a sequence of stars with weak Ha emission and magnitudes characteristic of BY Draconis stars; their offset above the main sequence also suggests they are probable binaries. The radial distributions for both the He WD and BY Dra candidates are significantly more centrally concentrated than the main-sequence stars, suggesting that indeed both populations are in binary systems.

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“…Long-term photographic photometry of other BY Dra variables using archival plate collections has already revealed remarkable amplitudes up to 1.0 mag (PZ Mon) with time-scales of 30-60 years in the case of active red dwarfs (Phillips & Hartmann 1978;Hartmann et al 1979;Hartmann et al 1981;Bondar' 1995;Alekseev & Bondar' 1998). These early investigations have been done by visual inspection of plates with magnifying glasses or iris photometry, respectively.…”

Section: Introductionmentioning

confidence: 99%

EK Draconis: Long-term photometry on Sonneberg Sky-Patrol plates

Fröhlich

Tschäpe

Rüdiger

et al. 2002

A&A

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Abstract. We performed long-term photometry of the young solar analog EK Draconis (HD 129333) using 1030 blue-sensitive Sky-Patrol plates taken at Sonneberg Observatory from 1958 onwards. A secular dimming of 0.0057 ± 0.0008 mag/y beginning around 1975 was found. Hence, the recent trend first observed with Automatic Photoelectric Telescopes (APTs) is confirmed and traced back to the mid-seventies.

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Statistics of BY Draconis variables

Cited by 14 publications

References 15 publications

New periodic variable stars coincident withROSATsources discovered using SuperWASP

New periodic variable stars coincident withROSATsources discovered using SuperWASP

Helium White Dwarfs and BY Draconis Binaries in the Globular Cluster NGC 6397

EK Draconis: Long-term photometry on Sonneberg Sky-Patrol plates

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