Open AccessTime‐series spectroscopy of pulsating sdB stars – II. Velocity analysis of PG 1605+072 ★
Author(s) -
O'Toole S. J.,
Bedding T. R.,
Kjeldsen H.,
Dall T. H.,
Stello D.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05537.x
Subject(s) - physics , amplitude , photometry (optics) , astrophysics , subdwarf , spectroscopy , stars , frequency analysis , oscillation (cell signaling) , asteroseismology , series (stratigraphy) , astronomy , optics , acoustics , paleontology , biology , genetics , white dwarf
We present the analysis of time‐resolved spectroscopy of the pulsating subdwarf B (sdB) star PG 1605+072. From our main observing run of 16 nights we have detected velocity variations at five frequencies that correspond to those found in photometry. Based on these data, there appears to be change in amplitude of the dominant modes over about a year. However, when we include extra observations to improve the frequency resolution, we find that some of the frequencies are split into two or three. Simulations suggest that the apparent amplitude variation can be at least partially explained by a series of very closely spaced frequencies around the two strongest modes. By combining observations taken over ∼300 d we conclude that some of the closely spaced modes are caused by one mode the amplitude of which is varying, however this frequency is still within ∼1 μHz of an apparently stable frequency. Because of this kind of complexity and uncertainty we advise caution when trying to identify oscillation modes in this star.