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Photometric Activity of the Rapidly Rotating Dm4.5e Star V639 Her
- Authors: Bondar N.I1, Antonyuk K.A1, Pit N.V1
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Affiliations:
- Crimean Astrophysical Observatory RAS
- Issue: Vol 65, No 7 (2025)
- Pages: 998–1004
- Section: Articles
- URL: https://bakhtiniada.ru/0016-7940/article/view/376068
- DOI: https://doi.org/10.7868/S3034502225070035
- ID: 376068
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Abstract
The paper presents the results of photometric studies of the M-dwarf V639 Her (M4.5Ve, M = 0.31M☉) based on CCD observations with the CrAO 1.25-m telescope in the BV(RI)c bands in 2019. The analysis of the light curves in these bands shows that the rotation period of the star is 1.457 days. With this period, low-amplitude changes occur in the stellar brightness in the observed ranges of the spectrum. As the brightness decreases, the color of the star becomes redder. The observed photometric features indicate the presence of cool spots on the surface of the star. The rotational modulation characteristics (the amplitude and phase of the minimum) were obtained from the phase light curves for each observation season. It is shown that the distribution of spots and the stability of the rotational modulation parameters persisted for about 100 days.
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About the authors
N. I Bondar
Crimean Astrophysical Observatory RAS
Email: otbn@mail.ru
Nauchny, Russia
K. A Antonyuk
Crimean Astrophysical Observatory RASNauchny, Russia
N. V Pit
Crimean Astrophysical Observatory RASNauchny, Russia
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