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Astronomy & Astrophysics manuscript no. 11419 c ESO 2008 December 10, 2008
 

Summary: Astronomy & Astrophysics manuscript no. 11419 c ESO 2008
December 10, 2008
LETTER TO THE EDITOR
Discovery of very low amplitude 9-minute multiperiodic
pulsations in the magnetic Ap star HD 75445
O. Kochukhov1, S. Bagnulo2, and G. Lo Curto3
1
Department of Physics and Astronomy, Uppsala University, SE-751 20, Uppsala, Sweden
2
Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK
3
European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Casilla 19001 Santiago 19, Chile
Received 25 November 2008 / Accepted 08 December 2008
ABSTRACT
We discovered pulsational radial velocity variations in the cool Ap star HD 75445 an object spectroscopically very similar to
the bright rapidly oscillating Ap (roAp) star Equ. Based on high-resolution time-series spectroscopy obtained with the HARPS
spectrometer at the European Southern Observatory 3.6-m telescope, we detected oscillations in Nd II and Nd III lines with a period
close to 9 min and amplitudes of 2030 m s-1
. Substantial variation of the pulsational amplitude during our 3.8 h observing run reveals
the presence of at least three excited non-radial modes. The detection of extremely low amplitude pulsations in HD 75445 indicates

  

Source: Armagh Observatory

 

Collections: Physics