Radial velocity variations of the pulsating subdwarf B star PG 1605+072

Abstract

We present an analysis of high-speed spectroscopy of the pulsating subdwarf B star PG 1605+072. Periodic radial motions are detected at frequencies similar to those reported for photometric variations in the star, with amplitudes of up to 6 km/s. Differences between relative strengths for given frequency peaks for our velocity data and previously measured photometry are probably a result of shifting of power between modes over time. Small differences in the detected frequencies may also indicate mode-shifting. We report the detection of line-shape variations using the moments of the cross correlation function profiles. It may be possible to use the moments to identify the star's pulsation modes.Comment: 5 pages, 6 figure

Interpreting the line-profile variations of subdwarf B pulsators: the case of PG 1336-018 (NY Virginis)

“…in the stars PB 8783 and KPD 1929+4401 (Jeffery & Pollacco 2000) and PG 1605+072 (Woolf et al 2002) to state a few. Recently, Telting et al (2008) used a cross-correlation technique on Balloon 090100001 to combine the information from many narrow metal lines into a single high S /N profile in order to investigate the signature of its oscillation modes.…”

“…The first time-resolved spectroscopy study was done by Jeffery & Pollacco (2000) on PB 8783 and KPD 1929+4401, followed by extensive studies on PG 1605+072 by Woolf et al (2002), O'Toole et al (2000O'Toole et al ( , 2002O'Toole et al ( , 2003aO'Toole et al ( , 2005 and Tillich et al (2007), on PG 1325+101 by Telting & Østensen (2004), on Balloon 090100001 by Telting & Østensen (2006) and Østensen et al (2008) and most recently on PG 1219+534 by Reed et al (2009). These low-resolution spectroscopy studies were mainly focused on measuring the RV and equivalent width variations, as well as characterization of the pulsational effective temperature and gravity variations.…”

“…This is the first application of a line-profile variation study on a V361 Hya star with low photometric amplitudes (<8 mmag), no dominant frequency and a dense and narrow frequency spectrum (28 frequencies were found in a 5000 μHz range, see Table 4 of Kilkenny et al 2003). All previous time-series spectroscopy studies, including the recent line-profile analysis by Telting et al (2008), were done on V361 Hya outliers with exceptionally high amplitudes (O'Toole et al 2000(O'Toole et al , 2002(O'Toole et al , 2003a(O'Toole et al , 2005Woolf et al 2002;Telting & Østensen 2004Telting & Østensen , 2006Tillich et al 2007). …”

Towards Asteroseismology of the Non-Radial Pulsating SDB Star PG 1605+072

“…The Multi-Site Spectroscopic-Telescope project (MSST): Our feasibility study as well as the previous ones (O 'Toole et al 2000, Woolf et al 2002 were unable to resolve the rich power spectrum of the RV and light curves. A considerably longer period of monitoring with as little gaps as possible is required to reach this goal.…”

“…These frequencies are consistent with previous photometry (Kilkenny et al 1999). A comparison with other feasibility studies (O'Toole et al 2000, Woolf et al 2002 shows that the power of the modes around 2.1 mHz and 2.75 mHz has switched in the course of the years 1999, 2000 and 2001. The light curves were measured with the new multi-band camera BUSCA (see Cordes et al 2003) at the 2.2 m telescope in four wavelength bands simultaneously.…”