scholarly journals Follow‐Up Observations of Pulsating Subdwarf B Stars: Multisite Campaigns on PG 1618+563B and PG 0048+091

2007 ◽  
Vol 664 (1) ◽  
pp. 518-535 ◽  
Author(s):  
M. D. Reed ◽  
S. J. O’Toole ◽  
D. M. Terndrup ◽  
J. R. Eggen ◽  
A.‐Y. Zhou ◽  
...  
Keyword(s):  
B Stars ◽  
Subdwarf B Stars

scholarly journals K2 observations of the pulsating subdwarf B stars UY Sex and V1405 Ori

2020 ◽  
Vol 492 (4) ◽  
pp. 5202-5217
Author(s):  
M D Reed ◽  
M Yeager ◽  
J Vos ◽  
J H Telting ◽  
R H Østensen ◽  
...  
Keyword(s):  
Rotation Period ◽  
B Stars ◽  
Subdwarf B Stars ◽  
Fundamental Properties ◽  
The Core ◽  
Rotation Periods ◽  
Short Period ◽  
Marginal Detection

ABSTRACT We processed and analysed K2 observations of the pulsating subdwarf-B (sdBV) stars UY Sex and V1405 Ori. We detect 97 p-mode pulsations in UY Sex while we discover V1405 Ori to be a rare rich hybrid pulsator with over 100 p-mode pulsations and 19 g-mode pulsations. We detect frequency multiplets, which we use to identify pulsation modes as well as determine rotation periods. For UY Sex, we find a rotation period of the envelope of 24.6 ± 3.5 d and for V1405 Ori, we find a rotation period of 0.555 ± 0.029 d for the p modes and a marginal detection of 4.2 ± 0.4 d for the g modes. We discover that V1405 Ori is unique among sdBV stars observed to date. It is a rich hybrid pulsator, allowing us to simultaneously probe the envelope and interior; its frequency multiplets indicate V1405 Ori to be rotating differentially with the core rotating more slowly than the envelope, and it is also in a short-period binary (0.398 d) with an envelope that is nearly but not quite tidally locked. For both stars, we have obtained spectroscopic follow-up observations and examine combining them with Gaia parallaxes and archival photometry to determine fundamental properties. Our derived masses are inconsistent with spectroscopy and previous determinations and indicate problems with the methodology.

scholarly journals First Kepler results on compact pulsators - III. Subdwarf B stars with V1093 Her and hybrid (DW Lyn) type pulsations

2010 ◽  
Vol 409 (4) ◽  
pp. 1496-1508 ◽  
Author(s):  
M. D. Reed ◽  
S. D. Kawaler ◽  
R. H. Østensen ◽  
S. Bloemen ◽  
A. Baran ◽  
...  
Keyword(s):  
B Stars ◽  
Subdwarf B Stars

scholarly journals Resolving the pulsations of subdwarf B stars: PG 0154+182, HS 1824+5745 and HS 2151+0857

2006 ◽  
Vol 369 (3) ◽  
pp. 1529-1536 ◽  
Author(s):  
M. D. Reed ◽  
J. R. Eggen ◽  
A.- Y. Zhou ◽  
D. M. Terndrup ◽  
S. L. Harms ◽  
...  
Keyword(s):  
B Stars ◽  
Subdwarf B Stars

scholarly journals A search for variable subdwarf B stars in TESS full frame images – I. Variable objects in the southern ecliptic hemisphere

2020 ◽  
Vol 499 (4) ◽  
pp. 5508-5526
Author(s):  
S K Sahoo ◽  
A S Baran ◽  
S Sanjayan ◽  
J Ostrowski
Keyword(s):  
Preliminary Analysis ◽  
Variable Stars ◽  
Eclipsing Binaries ◽  
Spectral Classification ◽  
B Stars ◽  
Mode Identification ◽  
Pulsating Stars ◽  
Subdwarf B Stars ◽  
Amplitude Spectra

ABSTRACT We report the results of our search for pulsating subdwarf B stars in full frame images, sampled at 30 min cadence and collected during Year 1 of the TESS mission. Year 1 covers most of the southern ecliptic hemisphere. The sample of objects we checked for pulsations was selected from a subdwarf B stars data base available to public. Only two positive detections have been achieved, however, as a by-product of our search we found 1807 variable objects, most of them not classified, hence their specific variability class cannot be confirmed at this stage. Our preliminary discoveries include: 2 new subdwarf B (sdB) pulsators, 26 variables with known sdB spectra, 83 non-classified pulsating stars, 83 eclipsing binaries (detached and semidetached), a mix of 1535 pulsators and non-eclipsing binaries, two novae, and 77 variables with known (non-sdB) spectral classification. Among eclipsing binaries we identified two known HW Vir systems and four new candidates. The amplitude spectra of the two sdB pulsators are not rich in modes, but we derive estimates of the modal degree for one of them. In addition, we selected five sdBV candidates for mode identification among 83 pulsators and describe our results based on this preliminary analysis. Further progress will require spectral classification of the newly discovered variable stars, which hopefully include more subdwarf B stars.

scholarly journals TESS observations of pulsating subdwarf B stars: extraordinarily short-period gravity modes in CD−28° 1974

2020 ◽  
Vol 493 (4) ◽  
pp. 5162-5169 ◽  
Author(s):  
M D Reed ◽  
K A Shoaf ◽  
P Németh ◽  
J Vos ◽  
M Uzundag ◽  
...  
Keyword(s):  
Main Sequence ◽  
Orbital Motion ◽  
Proper Motions ◽  
Reflection Effect ◽  
Echelle Spectrograph ◽  
Single Star ◽  
B Stars ◽  
Subdwarf B Stars ◽  
Short Period ◽  
Typical Period

ABSTRACT Transiting Exoplanet Survey Satellite (TESS) observations show CD−28° 1974 to be a gravity(g)-mode-dominated hybrid pulsating subdwarf B (sdBV) star. It shows 13 secure periods that form an ℓ = 1 asymptotic sequence near the typical period spacing. Extraordinarily, these periods lie between 1500 and 3300 s, whereas typical $\ell = 1\, g$ modes in sdBV stars occur between 3300 and 10 000 s. This indicates a structure somewhat different from typical sdBV stars. CD−28° 1974 has a visually close F/G main-sequence companion 1.33 arcsec away, which may be a physical companion. Gaia proper motions indicate a comoving pair with the same distance. A reanalysis of Ultraviolet and Visual Echelle Spectrograph (UVES) spectra failed to detect any orbital motion and the light curve shows no reflection effect or ellipsoidal variability, making an unseen close companion unlikely. The implication is that CD−28° 1974 has become a hot subdwarf via single star or post-merger evolution.

Asteroseismological Studies of Long‐Period Variable Subdwarf B Stars. I. A Multisite Campaign on PG 1627+017

2006 ◽  
Vol 643 (2) ◽  
pp. 1198-1218 ◽  
Author(s):  
S. K. Randall ◽  
G. Fontaine ◽  
E. M. Green ◽  
P. Brassard ◽  
D. Kilkenny ◽  
...  
Keyword(s):  
B Stars ◽  
Subdwarf B Stars ◽  
Long Period ◽  
Period Variable

scholarly journals The detection of binary companions to subdwarf B stars

1998 ◽  
Vol 298 (1) ◽  
pp. 179-184 ◽  
Author(s):  
C. S. Jeffery ◽  
D. L. Pollacco
Keyword(s):  
B Stars ◽  
Subdwarf B Stars

A Driving Mechanism for the Newly Discovered Long‐Period Pulsating Subdwarf B Stars

2003 ◽  
Vol 597 (1) ◽  
pp. 518-534 ◽  
Author(s):  
G. Fontaine ◽  
P. Brassard ◽  
S. Charpinet ◽  
E. M. Green ◽  
P. Chayer ◽  
...  
Keyword(s):  
Driving Mechanism ◽  
B Stars ◽  
Subdwarf B Stars ◽  
Long Period
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