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Spektrální analýza erupcí na AD Leo
Název práce v češtině: Spektrální analýza erupcí na AD Leo
Název v anglickém jazyce: Spectral analysis of flares on AD Leo
Klíčová slova: Hvězdy|Červení trpaslíci|Erupce|Spektra
Klíčová slova anglicky: Stars|Red dwarfs|Flares|Spectra
Akademický rok vypsání: 2020/2021
Typ práce: diplomová práce
Jazyk práce: čeština
Ústav: Astronomický ústav UK (32-AUUK)
Vedoucí / školitel: prof. RNDr. Petr Heinzel, DrSc.
Řešitel: skrytý - zadáno a potvrzeno stud. odd.
Datum přihlášení: 19.11.2020
Datum zadání: 19.02.2021
Datum potvrzení stud. oddělením: 05.04.2021
Datum a čas obhajoby: 01.07.2021 09:30
Datum odevzdání elektronické podoby:20.05.2021
Datum odevzdání tištěné podoby:21.05.2021
Datum proběhlé obhajoby: 01.07.2021
Oponenti: doc. Mgr. Daniela Korčáková, Ph.D.
Konzultanti: Petr Kabáth, Dr.
Zásady pro vypracování

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
Seznam odborné literatury
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.
Předběžná náplň práce v anglickém jazyce
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.
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