Spektrální analýza erupcí na AD Leo
| Thesis title in Czech: | Spektrální analýza erupcí na AD Leo |
|---|---|
| Thesis title in English: | Spectral analysis of flares on AD Leo |
| Key words: | Hvězdy|Červení trpaslíci|Erupce|Spektra |
| English key words: | Stars|Red dwarfs|Flares|Spectra |
| Academic year of topic announcement: | 2020/2021 |
| Thesis type: | diploma thesis |
| Thesis language: | čeština |
| Department: | Astronomical Institute of Charles University (32-AUUK) |
| Supervisor: | prof. RNDr. Petr Heinzel, DrSc. |
| Author: | hidden - assigned and confirmed by the Study Dept. |
| Date of registration: | 19.11.2020 |
| Date of assignment: | 19.02.2021 |
| Confirmed by Study dept. on: | 05.04.2021 |
| Date and time of defence: | 01.07.2021 09:30 |
| Date of electronic submission: | 20.05.2021 |
| Date of submission of printed version: | 21.05.2021 |
| Date of proceeded defence: | 01.07.2021 |
| Opponents: | doc. Mgr. Daniela Korčáková, Ph.D. |
| Advisors: | Petr Kabáth, Dr. |
| Guidelines |
| Workplan:
1) Reduction of OES spectra 2) Construction of light curves for selected lines and continuum bands 3) Comparison of light curves with those from small telescopes (broad-band) 4) Characterization of time evolution in various lines and continuum 5) Behaviour of line asymmetries, especially in the gradual phase of flares 6) Development of radiative-transfer model to explain asymmetries 7) Comparison of model line profiles with those from OES and from other published data 8) Discussion of results |
| References |
| Kowalski, A.F. 2012, PhD thesis, Univ. of Washington
Kabath, P. 2020, PASP 132c5002K (Ondrejov Echelle Spectrograph) Hawley, S. et al. 1995, ApJ 453, 464 Hawley, S. and co-authors: various papers dealing with AD Leo Fischer, G.H. and Hawley, S. 1990, ApJ 357, 243F Muheki, P. et al. 2020, A&A 637, A13 Heinzel, P. 2019, in The Sun as a Guide to Stellar Physics, Ch. 5, Elsevier Publ. |
| Preliminary scope of work in English |
| AD Leo is the dMe red-dwarf star exhibiting rich flare activity. There exist
various studies of this flare star, but a detailed understanding of its spectral behavior is still missing (e.g. A. Kowalski, PhD thesis 2012). Most recent spectral analysis was performed by Muheki et al.2020 using observations from echelle spectrograph attached to 2m telescope of the Tautenburg observatory in Germany. In 2019 similar observations have been initialized with OES (Ondrejov Echelle Spectrograph), attached to Perek 2m telescope. AD Leo was monitored during several nights and spectra were obtained for a few flares. Simultaneously, a broad-band photometry was carried out by several small telescopes within the Czech Republic (a campaign was organized together with Perek telescope). Second observing period in 2020 also provided additional AD Leo spectra, this time also a reference star was used for purposes of the absolute radiometric calibration. Within the master thesis the OES spectra from both campaigns will be reduced and analyzed with the aim to better understand the flare processes present on AD Leo. Light curves constructed from spectra in different lines and broad-band continuum bandpasses will be compared with photometric light curves from small telescopes. Temporal variations of the line intensities, and namely of hydrogen H-alpha, will be separated from continuum evolution. In case of the second campaign, the reference star will be used to perform absolute photometric calibration of spectra. These light curves and spectra will be compared with results of previous studies. A specific aim of the thesis will be a study of the line asymmetries which are due to atmospheric motions caused by the evolving flare. Namely the asymmetries detected during the gradual phase of flares (i.e. after the flare peak) have not been so far investigated quantitatively. A numerical radiative-transfer model of the gradual phase will be thus developed and computed line profiles will be compared with OES observations, but also with spectra obtained from Tautenburg 2m telescope. The work will be done with help of the stellar department of the Ondrejov observatory, Dr. Petr Kabath, PhD. will serve as a consultant. The master thesis will be supervised by Prof. Dr. Petr Heinzel, DrSc. from Astronomical Institute of the Czech Academy of Sciences. |