Author:

Keywords:

subdwarfs, early-type stars, oscillations, subdwarf-b stars, pg 1325+101, spectral-analysis, time-series, 0201 Astronomical and Space Sciences, Astronomy & Astrophysics

Abstract:

In this report we present preliminary results from time-series low-resolution spectroscopy of the pulsating sdB star PG 1325+101 obtained with the Nordic Optical Telescope. We have cross-correlated the spectra and Fourier analysed the resulting radial velocities. From the resulting periodograms we easily recover the known main pulsation period. Further analysis of the spectra, after binning them in phase according to the pulsation period, clearly shows evidence for line-profile variations consistent with a radial pulsation mode. The variations show up in all Balmer lines and several Helium lines sampled by the spectra, and can be understood in terms of temperature, gravity and radial velocity variations. To the best of our knowledge PG 1325+101 is the faintest object in which line-profile variation due to pulsational instability has been detected so far.