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Constraining the Hydrogen Envelope Mass of a Pulsating sdB Star KIC 10670103 Through Asteroseismology

Krzesinski J., Blokesz A., Baran A. S., Bachulski S.

Acta Astronomica

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2014

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Vol. 64, No. 2

151--165

EN

In this paper we present our study of KIC 10670103, a pulsating hot subdwarf located in the Kepler field. The study is based on three years of data taken by the Kepler spacecraft during Q5-16. Using Fourier analysis, we investigate periodic signals associated with pulsations. Using asymptotic relationships and rotational multiplets we identify modal degrees. The amplitude spectrum appears to be rich in l=1 and 2 multiplets, allowing derivation of a 90 days rotation period for this star. Comparing the pattern of identified gravity mode period spacings with theoretical models, we show that KIC 10670103 is a thick-envelope sdB star.

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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.

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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.