Abstract
The results of studies of superfast line profile variability in spectra of early-type star on minute and second time scales are reviewed. The spectra of bright OBA stars were obtained with the 6-meter BTA telescope of the Special Astrophysical Observatory (SAO, Russia). Additionally selected OBA stars were observed with the 1-m telescope of SAO and with the 1.25-m telescope of the Crimean Astronomical Station of SAI, Russia. The variations of the line profiles are analyzed. Regular line profiles variations (LPVs) of the H, HeI, FeII, NII, OII, and SiII in spectra of program stars with periods from 10 to ~120 minutes and amplitudes of 1–2% of the continuum level were detected. The short-time transient quasi-regular LPVs with periods from 1 to 10 minutes and lifetime in the interval 20–100 minutes were also registered. The periods of such transients appeared to be variable. Their frequencies can change up to 20% during their lifetime. A nature of such transients is unknown and a similarity of their generation to that for the five-minute solar oscillations is an open question. A connection between irregular LPVs and local magnetic fields generating the stellar micro-flares is proposed.
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REFERENCES
Afanasiev, V.L. and Moiseev, A.V., The SCORPIO universal focal reducer of the 6-m telescope, Astron. Lett., 2005, vol. 31, no. 3, pp. 194–204.
Balona, L.A., Spots and flares in hot main sequence stars, arXiv, 2008. https://arxiv.org/abs/2008.06305.
Borre, C.C., Baade, D., Pigulski, A., et al., Short-term variability and mass loss in be stars. V. Space photometry and ground-based spectroscopy of gamma Cas, Astron. Astrophys., 2020, vol. 635, id A140.
Dushin, V.V., Kholtygin, A.F., Chuntonov, G.A., and Kudryavtsev, D.O., Rapid spectral variability of ε PerA, Astrophys. Bull., 2013, vol. 68, no. 2, pp. 184–195.
Hubrig, S., Schöller, M., and Kholtygin, A.F., Short time-scale spectral variability in the A0 supergiant HD 92207 and the importance of line profile variations for the interpretation of FORS 2 spectropolarimetric observations, Month. Not. R. Astron. Soc., 2014, vol. 440, no. 2, pp. 1779–1785.
Jackson, B.V., Bungton, A., Hick, P.P., et al., The Solar Mass-Ejection Imager (SMEI) mission, Sol. Phys., 2004, vol. 225, pp. 177–207.
Kaper, L., Henrichs, H.F., Fullerton, A.W., et al., Coordinated ultraviolet and Hα spectroscopy of bright O-type stars, Astron. Astrophys., 1997, vol. 327, pp. 281–298.
Kholtygin, A.F., Monin, D.N., Surkov, A.E., and Fabrika, S.N., Fast line profile in the spectra of hot O stars, Astron. Lett., 2003, vol. 29, pp. 175–187.
Kholtygin, A.F., Hubrig, S., Dushin, V.V., et al., Fast spectral variations of OBA stars, ASP Conf. Ser., 2017, vol. 510, pp. 299–303.
Kholtygin, A.F., Ikonnikova, N.P., Dodin, A.V., and Tsiopa, O.A., Superfast line profile variability in the spectra of ρ Leo: New results, Astron. Lett., 2020, vol. 46, pp. 168–176.
Korzennik, S.G., Rabello-Soares, M.C., Schou, J., and Larson, T.P., Accurate characterization of high-degree modes using MDI observations, Astrophys. J., 2013, vol. 772, id 87.
Kosovichev, A., Properties of flares-generated seismic waves on the sun, Sol. Phys., 2006, vol. 238, pp. 1–11.
Le Contel, J.M., Sareyan, J.P., and Dantel, M., Short period variable stars. II. Variations in the spectrum of the beta CMa star HD 43818, Astron. Astrophys., 1970, vol. 8, pp. 29–40.
Di Mauro, M.P., A review on asteroseismology, in Frontier Research in Astrophysics II, Mondello, Italy, 2016, id 29.
McLaughlin, J.A., Nakariakov, V.M., Dominique, M., et al., Modelling quasi-periodic pulsations in solar and stellar flares, Space Sci. Rev., 2018, vol. 214, id 45.
Panchuk, V.E., Chuntonov, G.A., and Naidenov, I.D., Main stellar spectrograph of the 6-meter telescope. Analysis, reconstruction, and operation, Astrophys. Bull., 2014, vol. 69, pp. 339–355.
Plachinda, S. and Butkovskaya, V., Investigations of space magnetism at the Crimean Astrophysical Observatory. II. Direct spectropolarimetric measurements of stellar magnetic fields, Acta Astrophys. Taurica, 2020, vol. 1, pp. 26–36.
Poularikas, A.D., Ed., The Handbook of Formulas and Tables for Signal Processing, Boca Raton: CRC, 1999.
Smith, M.A., Henry, W.C., and Vishniak, E., Rotational and cyclical variability in γ Cas, Astrophys. J., 2006, vol. 647, pp. 1375–1386.
Telting, J.H. and Schrijvers, C., Line-profile variations of non-radial adiabatic pulsations of rotating stars. II. The diagnostic value of amplitude and phase diagrams derived from time series of spectra, Astron. Astrophys., 1997, vol. 317, pp. 723–741.
Weiss, W.W., Rucinski, S.M., Moffat, A.F.J., et al., BRITE-constellation: Nanosatellites for precision photometry of bright stars, Publ. Astron. Soc. Pac., 2014, vol. 126, pp. 573–585.
ACKNOWLEDGMENTS
Authors thanks RFBR grant 19-02-00311 А for the support. I.Ya. is grateful for the support of this work by the RFBR project no. 19-32-60 007. Observations with the SAO RAS telescopes are carried out with the support of the Ministry of Science and Higher Education of the Russian Federation (including agreement no. 05.619.21.0016, unique project identifier RFMEFI61919X0016).
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Kholtygin, A.F., Moiseeva, A.V., Yakunin, I.A. et al. Superfast Stellar Pulsations of Hot Stars. Geomagn. Aeron. 61, 923–927 (2021). https://doi.org/10.1134/S0016793221070100
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DOI: https://doi.org/10.1134/S0016793221070100