Multicolour high-speed photometry of pulsating subdwarf B stars with ULTRACAM
UNSPECIFIED. (2004) Multicolour high-speed photometry of pulsating subdwarf B stars with ULTRACAM. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 352 (2). pp. 699-707. ISSN 0035-8711Full text not available from this repository.
Official URL: http://dx.doi.org/10.1111/j.1365-2966.2004.07960.x
High-speed multicolour photometry is presented for two pulsating subdwarf B stars, KPD 2109+4401 and HS 0039+4302. The observations were obtained using the high-speed multichannel photometer ULTRACAM on the 4.2-m William Herschel Telescope with a sampling interval of 1 and 4 s, respectively, for the two targets. Both targets show multiperiodic oscillations, generally considered to be due to p-mode pulsations. The frequency spectra are similar to those observed previously, although the amplitudes of some modes have altered. The observations are compared with theoretical multicolour light curves for non-radially oscillating extreme horizontal branch stars using the amplitude ratio method. The radial and spherical degrees n and l of all unambiguously identified frequencies have been determined. In general, n less than or equal to 3 and l less than or equal to 2, but both stars show one l = 4 mode. The spectra of frequency versus spherical degree are compared with models for evolved extended horizontal branch stars. These confirm that KPD 2109+4401 has a post-zero-age horizontal branch age of approximately 47 Myr and an envelope mass similar to0.0002 M.. HS 0039+4302 lies on the upper edge of the horizontal branch and hence its envelope mass and age are less well determined spectroscopically. The pulsation properties suggest a more massive envelope and evolved structure. In both stars, the frequencies of the radial (l = 0) modes, if correctly identified, do not match the selected models well, suggesting that the density structure or opacity in the stellar envelopes may be incorrect.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Journal or Publication Title:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY|
|Publisher:||BLACKWELL PUBLISHING LTD|
|Official Date:||1 August 2004|
|Number of Pages:||9|
|Page Range:||pp. 699-707|
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