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Mount Suhora High Cadence Photometric Survey of T Tauri-Type Stars

Siwak M., Dróżdż M., Gut K., Winiarski M., Ogłoza W., Stachowski G.

Acta Astronomica

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2019

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Vol. 69, No. 3

227--260

EN

Results of high-cadence multi-color observations of 121 pre-main sequence stars available from the northern hemisphere are presented. The aim of this survey was to detect transit-like signatures caused by occultation of these young stars and their accretion-induced hot spots by close-in planets and/or dusty clumps. Although none planetary transits were detected, our data allow the determination of rotational periods for some T Tau stars and characterization of the accretion processes operating in classical T Tau-type stars in time scales ranging from a few minutes to days, as well as characterization of the large-scale dips caused by dusty warped disks.

2

Multicolor Photometry of SV Cam in 1997

Kjurkchieva D., Marchev D., Ogłoza W.

Acta Astronomica

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2000

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Vol. 50, No. 4

517--528

EN

High speed BVR(I)C photometry of the short period RS CVn binary SV Cam is presented. Its light curve is asymmetric with a depression of brightness by 0.04-0.05 mag after the primary eclipse. Good fit of the synthetic light curve to the observational data in all colors can be obtained assuming presence of two cool spots with equal angular sizes of 20° and temperatures 4350 K located at middle latitude above and below the stellar equator on opposite hemispheres of the primary star.

3

Fourier Analysis of Hipparcos Photometry of Cepheid Variables

Zakrzewski B., Ogłoza W., Moskalik P.

Acta Astronomica

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2000

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Vol. 50, No. 3

387--397

EN

Fourier parameters have been computed for 240 field Cepheids observed by the Hipparcos satellite. We have identified three new Population I overtone Cepheids: V411 Lac, V898 Cen and V572 Aql. We have compared Fourier progressions of Population I and Population II Cepheids. The possibility of using Fourier parameters to distinguish between the two types is discussed.

4

Hα Observations of SS Cyg at Quiescence and Outburst

Marchev D., Kjurkchieva D., Ogłoza W.

Acta Astronomica

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1999

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Vol. 49, No. 4

585--598

EN

Observations of Hα line of SS Cyg at quiescence and outburst are presented. The corresponding radial velocity curve is sinusoidal with semiamplitude K1=91±3.5 km/s. The width and intensity of the Hα line during quiescence are slightly variable. Its profile shape changes quite irregular but does not show the typical double-peaked structure of an accretion disk. The small peaks at the profile cores form S-wave with half-orbital period. The Hα profiles of SS Cyg at outburst consist of central emission core superposed on wide shallow absorption base. The intensity of the emission core is almost the same as that of the emission line in quiescence. The double-peaked shape of the profile is not well pronounced during the outburst too. On the base of the parameters of the Hα profile we estimate that the condition for the existence of an accretion disk during quiescence is not fulfilled. Such a structure can exist in outburst but it cannot be a dominant source of the Hα emission. Taking into account similarity of SS Cyg and the polar AM Her we conclude that the Balmer emission of SS Cyg originates mostly from the polar caps.