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Whole Earth Telescope Observations Of The Pulsating Subdwarf B Star Pg 0014+067, Maja Vučković, Matt A. Wood, V. Wilkat
Whole Earth Telescope Observations Of The Pulsating Subdwarf B Star Pg 0014+067, Maja Vučković, Matt A. Wood, V. Wilkat
Aerospace, Physics, and Space Science Faculty Publications
PG 0014+067 is one of the most promising pulsating subdwarf B stars for seismic analysis, as it has a rich pulsation spectrum. The richness of its pulsations, however, poses a fundamental challenge to understanding the pulsations of these stars, as the mode density is too complex to be explained only with radial and nonradial low-degree (l < 3) p-modes without rotational splittings. One proposed solution, suggested by Brassard et al. in 2001 for the case of PG 0014+067 in particular, assigns some modes with high degree (l - 3). On the other hand, theoretical models of sdB stars suggest that they may retain rapidly rotating cores, and so the high mode density may result from the presence of a few rotationally split triplet (l = 1) and quintuplet (l = 2) modes, along with radial (l = 0)p-modes. To examine alternative theoretical models for these stars, we need better frequency resolution and denser longitude coverage. Therefore, we observed this star with the Whole Earth Telescope for two weeks in 2004 October. In this paper we report the results of Whole Earth Telescope observations of the pulsating subdwarf B star PG 0014+067. We find that the frequencies seen in PG 0014+067 do not appear to fit any theoretical model currently available; however, we find a simple empirical relation that is able to match all of the well-determined frequencies in this star.
The Rapidly Pulsating Subdwarf B Star Pg 1325+101 I. Oscillation Modes From Multisite Observations, R Silvotti, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston
The Rapidly Pulsating Subdwarf B Star Pg 1325+101 I. Oscillation Modes From Multisite Observations, R Silvotti, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston
Aerospace, Physics, and Space Science Faculty Publications
In this article we present the results of 215 h of time-series photometry on the rapidly pulsating subdwarf B star PG 1325+101 (Teff - 35 000 K, log g = 5.8, log N(Hs)/N(H) = -1.7), obtained during 25 days of observation in Spring 2003 from nine different sites. As in previous observations, the temporal spectrum is dominated by the main peak at 7255.55 μHz, with an amplitude of about 2.7% which, however, is dropped to about 1.7% in February 2005. No secondary peaks close to the dominant pulsation mode are clearly detected. In addition, at least fourteen more pulsation frequencies …
The Rapidly Pulsating Subdwarf B Star Pg 1325+101 Ii. Structural Parameters From Asteroseismology, Stéphane Charpinet, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston
The Rapidly Pulsating Subdwarf B Star Pg 1325+101 Ii. Structural Parameters From Asteroseismology, Stéphane Charpinet, T D. Oswalt, Mark J. Rudkin, Kyle B. Johnston
Aerospace, Physics, and Space Science Faculty Publications
We present a detailed analysis of the rapidly pulsating subdwarf B star (or EC14026 star) PG 1325+101. This analysis exploits the outcome of dedicated multisite observations using time-series photometry that revealed the presence of (at least) 15 periodicities in the luminosity modulation of this star (Silvotti et al. 2006, A&A, 459, 557, Paper I). Based on high-S/N, medium-resolution spectra obtained at the Steward Observatory's 2.3 m Telescope and at the 6.5 m MMT Telescope, new NLTE spectroscopic derivations of the atmospheric parameters of PG 1325+101 are presented. The mean values of T eff = 35 050 ± 220 K, log …
A Multisite Photometric Campaign On The Pre-Main-Sequence Δ Scuti Pulsator Ip Persei, Vincenzo Ripepi, T D. Oswalt
A Multisite Photometric Campaign On The Pre-Main-Sequence Δ Scuti Pulsator Ip Persei, Vincenzo Ripepi, T D. Oswalt
Aerospace, Physics, and Space Science Faculty Publications
We present the results of a photometric multisite campaign on the δ Scuti Pre-Main-Sequence star IP Per. Nine telescopes have been involved in the observations, with a total of about 190 h of observations over 38 nights. Present data confirms the multiperiodic nature of this star and leads to the identification of at least nine pulsational frequencies. Comparison with the predictions of linear non-adiabatic radial pulsation models allowed us to identify only five of the nine observed frequencies, and to constrain the position of IP Per in the HR diagram. The latter is in good agreement with the empirical determination …
Whole Earth Telescope Observations Of The Zz Ceti Star Hl Tau 76, Noël Dolez, Matt A. Wood, Thomas J. Ahrens, Nicole Silvestri
Whole Earth Telescope Observations Of The Zz Ceti Star Hl Tau 76, Noël Dolez, Matt A. Wood, Thomas J. Ahrens, Nicole Silvestri
Aerospace, Physics, and Space Science Faculty Publications
This paper analyses the Whole Earth Telescope observations of HL Tau 76, the first discovered pulsating DA white dwarf. The star was observed during two Whole Earth Telescope campaigns. It was a second priority target during the XCOV13 campaign in 1996 and the first priority one during the XCOV18 campaign in 1999. The 1999 campaign reached 66.5% duty cycle. With a total duration of 18 days, the frequency resolution achieved is 0.68 μHz. With such a frequency resolution, we were able to find as many as 78 significant frequencies in the power spectrum, of which 34 are independent frequencies after …