ELFT HÍRADÓ

[Uhlár Karola <uhlar AT konkoly.hu>]

*MTA CSFK CSI
INTÉZETI SZEMINÁRIUM*

Előadó:***Markus Hareter* (MTA CSFK CSI)

Előadás címe: *HD 51844: an eccentric delta Scuti star *

Kivonat:
HD 51844 is a binary system composed of two nearly equal stars, where 
one component pulsates. The orbital period is 33.5 days and the 
eccentricity is 0.49. We could identify 115 pulsation frequencies where 
the dominant four frequencies account for most of the pulsational light 
variation. The pulsation frequencies show resonances (ratios of 3:2, 3:4 
and 3:5), an effect which has not yet been reported for delta Scuti 
stars. Moreover, the light curve shows a brightening event of 3 mmag, 
but no eclipses. Thus, HD 51844 is the first "Heartbeat" star reported 
among the CoRoT targets. A dedicated spectroscopic campaign allowed to 
derive the radial velocity curves and the chemical composition of the 
photosperes. Both stars are chemically peculiar of Delta Delphini type, 
meaning (mild) Am/Fm peculiarities. Both components exhibit strong lines 
of s-process elements, but the most significant difference is in Sc. 
While the pulsating star shows weak Sc lines, the nonpulsating star 
shows a slightly subsolar Sc abundance. When comparing the frequency 
modulation from photometry to the analysis of the radial velocities from 
spectroscopy, one finds that for such stars, the spectroscopic analysis 
is superior to the analysis of light curve alone, even though the CoRoT 
light curve is of excellent quality. We also searched for the possible 
"large separation" of the pulsation frequencies and found a good 
candidate spacing of 1.74 c/d.

Előadás időpontja: *2014. március 6. (csütörtök), 14:00**
*
Előadás helyszíne: MTA CSFK CSI Előadóterme
1121 Budapest, Konkoly T. M. út 15-17.
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fn:Karola Uhlar
n:Uhlar;Karola
org:Konkoly Observatory
adr:;;Konkoly Thege M. u. 13-17.;Budapest;;1121;Hungary
email;internet:uhlar AT konkoly.hu
title:secretary
tel;work:+3613919322
tel;fax:+3612754668
version:2.1
end:vcard