Chromospheric activity in H and K lines of Arcturus on 1984 February 14 |
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| Institution: | 1. Astronomy Department, National Research Institute of Astronomy and Geophysics (NRIAG), 11421 Helwan, Cairo, Egypt;2. Kottamia Center of Scientific Excellence in Astronomy and Space Science (KCScE, STDF, ASRT), Cairo, Egypt;1. Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), University of Maragheh, P.O. Box: 55136-553, Maragheh, Iran;2. Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz, P.O. Box: 5166616471, Iran;3. Department of Theoretical Physics and Astrophysics, Faculty of Physics, University of Tabriz, Tabriz, P.O. Box: 51666-16471, Iran;4. Astronomical institute, Academy of Sciences of the Czech Republic (v.v.i.), fričova 298, 25165 Ondřejov, Czech Republic;1. Astronomy Department, National Research Institute of Astronomy and Geophysics, 11421 Helwan, Cairo, Egypt;2. Department of Physics and Astronomy, Faculty of Science, King Saud University, P.O. Box 2455, 11451 Riyadh, Saudi Arabia;3. Department of Astronomy and Meteorology, Faculty of Science, Al-Azhar University, 11889 Nasr City, Cairo, Egypt |
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| Abstract: | We have obtained a large amount of high-dispersion spectra of Arcturus using our coude spectrograph attached to our 1-metre telescope. From this collection, we picked out an unbroken sequence of 5 spectra of the CaII H and K lines taken in a period of 4 hours on 1984 February 14. Their analysis shows that we were possibly witnessing a chromospheric eruption on the star. The following sequence was seen: the line profile became asymmetrical — the asymmetry remained while the peak emission increased — the profile became symmetrical once again. The largest asymmetry was 20% between the red and violet components of K2, and the maximum peak emission was some 20% above normal. There were also changes in K1. At the peak emission of K2 emission core appeared in the self-absorbed centre of K3. |
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