QUASI-PERIODIC PULSATIONS IN FLARES OF UV CETI-TYPE STARS
Section: STARS AND THE INTERSTELLAR MEDIUM
Authors:
1.
Togliatti State University
Special Astrophysical Observatory of the Russian Academy of Sciences
Special Astrophysical Observatory of the Russian Academy of Sciences
2.
University of Warwick
Ventspils University of Applied Sciences
Ventspils University of Applied Sciences
3.
Special Astrophysical Observatory of the Russian Academy of Sciences
Kazan Federal University
Kazan Federal University
4.
Institute of Physics of the Czech Academy of Sciences
5.
Special Astrophysical Observatory of the Russian Academy of Sciences
6.
Astronomical Institute of Czech Academy of Sciences
Type:
Сonference article
Published:
27.12.2024
Subject area:
UDK 52
UDK 53
UDK 520
UDK 521
UDK 523
UDK 524
UDK 52-1
UDK 52-6
GRNTI 41.00
GRNTI 29.35
GRNTI 29.31
GRNTI 29.33
GRNTI 29.27
GRNTI 29.05
OKSO 03.06.01
OKSO 03.05.01
OKSO 03.04.03
BBK 2
BBK 223
TBK 614
TBK 6135
BISAC SCI004000 Astronomy
BISAC SCI005000 Physics / Astrophysics
UDK 53
UDK 520
UDK 521
UDK 523
UDK 524
UDK 52-1
UDK 52-6
GRNTI 41.00
GRNTI 29.35
GRNTI 29.31
GRNTI 29.33
GRNTI 29.27
GRNTI 29.05
OKSO 03.06.01
OKSO 03.05.01
OKSO 03.04.03
BBK 2
BBK 223
TBK 614
TBK 6135
BISAC SCI004000 Astronomy
BISAC SCI005000 Physics / Astrophysics
Language:
English
Keywords:
stars: flares, oscillations, low-mass
Abstract (English):
Quasi-periodic pulsations (QPPs) were observed in the light curves of solar and stellar flares. The number of stellar QPP events is quite small (213 in 2021), which is why they are interesting. QPPs can be used to investigate the properties of flare regions and they are still a problem for flare models. QPPs were identified in stellar flares across a wide range of wavelengths, from radio to X-rays. In the optical band they are searched mainly in the Kepler and TESS data. The periods of QPPs detected from these sources are longer (tens of minutes) than from the high cadence data. Observations with the 6-m telescope BTA and the MANIA complex, as well as the space observatory GALEX, reveal QPP periods of only tens of seconds. On the other hand, solar flares are typically weaker (energies $\ll 10^{32}$ erg) than stellar flares, that possibly makes them more difficult to detect in white light. Our data on 157 flares of dM-type stars (EV Lac, Wolf 359, Wolf 424, V577 Mon, and UV Ceti), obtained from 70 hours of observations with the BTA telescope in $U$-band with microsecond time resolution, represents a significant breakthrough in the search for QPPs in stars. In this paper, we present the characteristics of 13 QPPs found in 44 flares. The QPPs have periods ranging from 6 to 107 seconds, and were identified using both Fourier transform and empirical mode decomposition methods. We classify the observed QPPs based on the evolution of their oscillation envelopes and fractional flux amplitudes.
Quasi-periodic pulsations (QPPs) were observed in the light curves of solar and stellar flares. The number of stellar QPP events is quite small (213 in 2021), which is why they are interesting. QPPs can be used to investigate the properties of flare regions and they are still a problem for flare models. QPPs were identified in stellar flares across a wide range of wavelengths, from radio to X-rays. In the optical band they are searched mainly in the Kepler and TESS data. The periods of QPPs detected from these sources are longer (tens of minutes) than from the high cadence data. Observations with the 6-m telescope BTA and the MANIA complex, as well as the space observatory GALEX, reveal QPP periods of only tens of seconds. On the other hand, solar flares are typically weaker (energies $\ll 10^{32}$ erg) than stellar flares, that possibly makes them more difficult to detect in white light. Our data on 157 flares of dM-type stars (EV Lac, Wolf 359, Wolf 424, V577 Mon, and UV Ceti), obtained from 70 hours of observations with the BTA telescope in $U$-band with microsecond time resolution, represents a significant breakthrough in the search for QPPs in stars. In this paper, we present the characteristics of 13 QPPs found in 44 flares. The QPPs have periods ranging from 6 to 107 seconds, and were identified using both Fourier transform and empirical mode decomposition methods. We classify the observed QPPs based on the evolution of their oscillation envelopes and fractional flux amplitudes.
Keywords:
stars: flares, oscillations, low-mass
stars: flares, oscillations, low-mass
1. Doyle J.G., Shetye J., Antonova A.E., et al., 2018, Monthly Notices of the Royal Astronomical Society, 475, 2, p. 2842
2. Nisticó G., Pascoe D.J., Nakariakov V.M., 2014, Astronomy & Astrophysics, 569, id. A12
3. Plokhotnichenko V.L., Beskin G.M., de Boer V.G., et al., 2021, Astrophysical Bulletin, 76, 4, p. 472
