Pravidelné semináře pořádáme jednou měsíčně (říjen–červen, zpravidla první pondělí v měsíci) od 13 hod v seminární místnosti pracoviště Ondřejov.
05. 11. 2012
Omicron Puppis: another Be + sdO binary?
Abstract: The spectrum of the Be star o Pup is shown to vary periodically with a period of 28.9 days. A
radial-velocity variable He I 6678 A emission component suggests that the star is the same type as
phi Per, 59 Cyg and FY CMa, i.e. binaries consisting of a Be star and a hot companion that
illuminates the Be star disk (also called phi Per-type binaries or Be+sdO binaries). The range of
radial-velocity variations of the stronger emission component in the helium line observed in o Pup
is about 270 km/s, a value which is in good agreement with the range derived for phi Per-type
binaries. The radial velocity curves defined by the prominent emission peak in He I 6678 A line and
H alpha + Paschen emission move in anti-phase. We suggest that o Pup is generically similar to phi
Per-type systems and may represent the fourth case of a Be star with a hot subdwarf companion.
Dále pořádáme menší semináře jednotlivých oddělení:
Semináře slunečního oddělení
Každé úterý v 13:00 (září–červen, s výjimkou úterků po celoústavním semináři) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
30/10/2012, 13:002D MHD numerical simulations of impulsively generated magnetoacoustic wavesAbstract: 2D MHD numerical simulations of impulsively generated propagating fast magnetoacoustic waves can be used for a diagnostics of individual solar coronal structures (e.g. flare loops or flare current sheets). We analyze the observations of solar flares, especially in the radio range of the electromagnetic spectrum, using methods of wavelet analysis. This analysis along with the MHD numerical simulations can allow us to determine the characteristic plasma parameters of the coronal structures and the relationship between the coronal structures and magnetoacoustic waves propagating in these structures. The first results of these simulations will be presented as well as a brief information about the cooperation with scientists from the Pulkovo Observatory, Institute of Solar-Terrestrial Physics in Irkutsk (FP7 IRSES RadioSun project), and Astronomical Institute SAV in Tatranska Lomnica (CAS-SAV Priority Theme).
Zářivě-(magneto)hydrodynamické semináře
Zpravidla 1x za 14 dní ve čtvrtek od 11 hod (říjen–červen) v zasedací místnosti slunečního oddělení pracoviště Ondřejov.
01/12/2011, 11:00Konkoly Observatory, Budapest, HungaryThe extreme outburst of the young eruptive star EX Lupi in 2008Abstract: EX Lupi is the prototype of EXors, a spectacular group of low-mass pre-main sequence stars characterized by repetitive optical outbursts of 1-5 mag lasting for a few months-to-few years. The outburst is attributed to enhanced accretion from the inner circumstellar disk (within ^X0.1AU) to the stellar surface, probably triggered by an instability in the disk. The historically largest outburst of EX Lupi in 2008 Jan-Sep offered a unique opportunity to understand deeper the physics of the EXor eruptions. In my talk I will summarize the main results of our coordinated observing campaign, in which we used a large set of telescopes to observe and characterize the path of accretion from the disk onto the stellar surface, with the aim of comparing the different models of outburst physics. Our measurements also demonstrated that the brief episodes of highly increased accretion, apart from contributing to the build-up of the final stellar mass, have substantial effect on the structure and composition of the circumstellar material: We discovered episodic crystallization of silicate grains in the disk surface due to the increased luminosity during the 2008 outburst, resulting in material that forms the building blocks of comets and planets.
Semináře oddělení GPS
Zpravidla v knihovně pracoviště Praha–Spořilov v různé dny.
V nejbližší době nejsou plánovány žádné semináře.