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Mon. Not. R. Astron. Soc. 000, 1{7 (0000) Printed 20 April 2000 (MN L A T E X style le v1.4) Radial velocities of pulsating subdwarf B stars
 

Summary: Mon. Not. R. Astron. Soc. 000, 1{7 (0000) Printed 20 April 2000 (MN L A T E X style le v1.4)
Radial velocities of pulsating subdwarf B stars:
KPD 2109+4401 and PB 8783 ?
C. Simon Je ery 1 and Don Pollacco 2;3
1 Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland
2 Isaac Newton Group, La Palma
3 Queens University Belfast, Belfast BT7 1NN, Northern Ireland
Accepted . Received ;
ABSTRACT
High-speed spectroscopy of two pulsating subdwarf B stars, KPD 2109+4401 and
PB 8783, is presented. Radial motions are detected with the same frequencies as re-
ported from photometric observations and with amplitudes of  2 km s 1 in two or
more independent modes. These represent the rst direct observations of surface mo-
tion due to multimode non-radial oscillations in subdwarf B stars. In the case of the
sdB+F binary PB 8783, the velocities of both components are resolved; high-frequency
oscillations are found only in the sdB star and not the F star. There also appears to
be evidence for mutual motion of the binary components. If con rmed, it implies that
the F-type companion is >  1:2 times more massive than the sdB star, while the am-
plitude of the F star acceleration over 4 hours would constrain the orbital period to
lie between 0.5 and 3.2d.

  

Source: Armagh Observatory

 

Collections: Physics