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Mon. Not. R. Astron. Soc. 000, 000--000 (0000) Printed 14 August 1997 (MN L A T E X style file v1.4) Spectral analysis of the high gravity extreme helium star
 

Summary: Mon. Not. R. Astron. Soc. 000, 000--000 (0000) Printed 14 August 1997 (MN L A T E X style file v1.4)
Spectral analysis of the high gravity extreme helium star
LS IV+6 ffi 2 ?
C. Simon Jeffery 1
1 Armagh Observatory, College Hill, Armagh BT61 9DG
Accepted . Received ;
ABSTRACT
The optical spectrum of the early­B hydrogen­deficient star LSIV+6 ffi 2 has been anal­
ysed. With T eff = 31 000K; logg = 4:05; nH ¸ 10 \Gamma4 ; nC ¸ 0:1, it is the hottest high­
gravity extreme helium star yet studied. The He i spectrum shows all predicted permit­
ted and forbidden transitions in absorption. LSIV+6 ffi 2 is a comparatively metal­rich
EHe star; abundances of C, N, O, Ne, Mg, Al, and P, are typical of other EHes, whilst Si
and S are somewhat deficient. With the surface parameters given, LSIV+6 ffi 2 lies close
to the boundary of the helium­star pulsation instability finger near T eff ¸ 27 000K.
Available data indicate that the radial­velocity is variable, but give no indication of
amplitude or period.
Key words: stars: helium, stars: individual (LS IV+6 ffi 2), stars: abundances
1 INTRODUCTION
The star LS IV+6 ffi 2 (V = 12:2; ff 2000 = 18 06 55:3; ffi 2000 =
+06 21 46) was found to be hydrogen­deficient by Drilling

  

Source: Armagh Observatory

 

Collections: Physics