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1
Content available remote 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
Content available remote Mt. Suhora Survey - Searching for Pulsating M Dwarfs. III
Baran A. S., Winiarski M., Siwak M., Fox-Machado L., Kozieł-Wierzbowska D., Krzesinski J., Dróżdz M., Winans A.
Acta Astronomica
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2013
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Vol. 63, No. 1
41--52
EN
We present our final report on the search for pulsating M dwarfs. We used moderate (<1 m) ground-based telescopes. Our detection was limited to 1 ppt, which is roughly 0.1% of flux variation. We employed both the Fourier technique and Phase Dispersion Minimization (PDM) method. Our data analyses revealed no detection of pulsations in M dwarfs down to the above amplitude level. The results of our survey cannot reject or confirm the theoretical calculations suggesting the M dwarfs can pulsate, however, if the pulsations exist in these stars their amplitudes must be lower than 1 ppt. As a by-product of our search we found several new variable stars, including pulsating stars, binary systems and flare stars.
3
Content available remote Mt. Suhora Survey - Searching for Pulsating M Dwarfs. II
Krzesinski J., Baran A. S., Winiarski M., Fox-Machado L., Dróżdż M., Siwak M., Kozieł-Wierzbowska D.
Acta Astronomica
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2012
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Vol. 62, No. 2
201--212
EN
We present our report on the second part of our ongoing project which aims at finding stellar pulsations in early type M dwarfs. Our search is based on time-series photometric data acquired mainly at Mt. Suhora Observatory, though, several stars have been observed from other sites. Data of 49 M dwarfs are included in this paper. We analyzed the data by means of the Fourier technique as well as Phase Dispersion Minimization method. We still cannot confirm any pulsating M dwarf at the model-predicted period of 23-40 min. In addition to our main goal we searched for flare activities, planetary transits and other types of brightness changes. We did find several new variable stars, including pulsating stars, binary systems and flare stars, however, only flaring M dwarfs are presented in this paper.
4
Content available remote A Study of Contact Binaries with Large Temperature Differences between Components
Siwak M., Zola S., Koziel-Wierzbowska D.
Acta Astronomica
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2010
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Vol. 60, No. 4
305--336
EN
We present an extensive analysis of new light and radial velocity (RV) curves, as well as high quality broadening function (BF) profiles of twelve binary systems for which a contact configuration with large temperature differences between components has been reported in the literature. We find that six systems (V1010 Oph, WZ Cyg, VV Cet, DO Cas, FS Lup, V747 Cen) have near contact configurations. For the remaining systems (CX Vir, FT Lup, BV Eri, FO Hya, CN And, BX And), our solutions of the new observations once again converge in a contact configuration with large temperature differences between the components. However, the bright regions discovered in the BFs for V747 Cen, CX Vir, FT Lup, BV Eri, FO Hya, and CN And, and further attributed to hot spots, shed new light on the physical processes taking place between the components and imply the possibility that the contact configurations obtained from light and RV curve modeling are a spurious result.
5
Content available remote Physical Parameters of Components in Close Binary Systems. V
Zola S., Kreiner J. M., Zakrzewski B., Kjurkchieva D. P., Marchev D. V., Baran A., Rucinski S. M., Ogloza W., Siwak M., Koziel D., Drozdz M., Pokrzywka B.
Acta Astronomica
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2005
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Vol. 55, No. 4
389--405
EN
The paper presents combined spectroscopic and photometric orbital solutions for ten close binary systems: CN And, V776 Cas, FU Dra, UV Lyn, BB Peg, V592 Per, OU Ser, EQ Tau, HN UMa and HT Vir. The photometric data consist of new multicolor light curves, while the spectroscopy has been recently obtained within the radial velocity program at the David Dunlap Observatory (DDO). Absolute parameters of the components for these binary systems are derived. Our results confirm that CN And is not a contact system. Its configuration is semi-detached with the secondary component filling its Roche lobe. The configuration of nine other systems is contact. Three systems (V776 Cas, V592 Per and OU Ser) have high (44-77%) and six (FU Dra, UV Lyn, BB Peg, EQ Tau, HN UMa and HT Vir) low or intermediate (8-32%) fill-out factors. The absolute physical parameters are derived.
6
Content available remote Physical Parameters of Components in Close Binary Systems: IV
Gazeas K. D., Baran A., Niarchos P., Zola S., Kreiner J. M., Ogloza W., Rucinski S. M., Zakrzewski B., Siwak M., Pigulski A., Dróżdż M.
Acta Astronomica
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2005
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Vol. 55, No. 1
123--140
EN
The paper presents new geometric, photometric and absolute parameters, derived from combined spectroscopic and photometric solutions, for ten contact binary systems. The analysis shows that three systems (EF Boo, GM Dra and SW Lac) are of W-type with shallow to moderate contact. Seven systems (V417 Aql, AH Aur, YY CrB, UX Eri, DZ Psc, GR Vir and NN Vir) are of A-type in a deep contact configuration. For six systems (V417 Aql, YY CrB, GM Dra, UX Eri, SW Lac and GR Vir) a spot model is introduced to explain the O'Connell effect in their light curves. The photometric and geometric elements of the systems are combined with the spectroscopic data taken at David Dunlap Observatory to yield the absolute parameters of the components.
7
Content available remote Physical Parameters of Components in Close Binary Systems: II
Baran A., Zola S., Rucinski S. M., Kreiner J. M., Siwak M., Drozdz M.
Acta Astronomica
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2004
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Vol. 54, No. 2
195--206
EN
We present the absolute parameters of components for five contact binary systems: AB And, GZ And, AO Cam, DN Cam and DK Cyg. The results are based on solutions of new multicolor light curves as well as new radial velocity curves from the DDO radial velocity program. All five systems have a contact configuration with low (5-13%) to intermediate (30-33%) overfilling factors.
8
Content available remote Physical Parameters of Components in Close Binary Systems: III
Zola S., Rucinski S. M., Baran A., Ogloza W., Pych W., Kreiner J. M., Stachowski G., Gazeas K., Niarchos P., Siwak M.
Acta Astronomica
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2004
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Vol. 54, No. 3
299--312
EN
The paper presents combined spectroscopic and photometric orbital solutions for five close binary systems: V402 Aur, SX Crv, V829 Her, VZ Lib and V753 Mon. The photometric data consist of new complete, multicolor light curves, while the spectroscopy has been recently obtained within the radial velocity program at the David Dunlap Observatory. For one target, SX Crv, new spectroscopic data were obtained using the 6.5 m Magellan telescope. A contact configuration was found through light curve modeling for all targets except V753 Mon. Our solution for V753 Mon resulted in a semidetached configuration with the slightly less massive component filling its Roche lobe.
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