# Temperature and gravity of the pulsating extreme helium star LSS 3184 (BX Cir) through its pulsation cycle

@article{Woolf2002TemperatureAG,
title={Temperature and gravity of the pulsating extreme helium star LSS 3184 (BX Cir) through its pulsation cycle},
author={Vincent M Woolf and C. Simon Jeffery},
journal={Astronomy and Astrophysics},
year={2002},
volume={395},
pages={535-540}
}
• Published 14 August 2002
• Physics, Geology
• Astronomy and Astrophysics
We report the analysis of optical spectra of the extreme helium star LSS 3184 (BX Cir) to determine its effective temperature and gravity throughout its pulsation cycle. The spectra were also used to measure its chemical abundances. We report rest gravity, log g = 3.38 +/- 0.02, and a chemical abundance mixture consistent with those reported earlier in a study using an optical spectrum with lower spectral resolution and a lower signal to noise ratio. Our analysis decreases the upper limit for…
9 Citations

## Figures and Tables from this paper

Period changes in the pulsating extreme helium stars V652 Her and BX Cir
• Physics
• 2005
Thirty-four new timings of maxima of the radially pulsating extreme helium (EHe) star V652 Her (=BD+13° 3224) obtained during 1996-2004 are reported. The quartic ephemeris (for the pulsation period
Precision diagnostics of pulsation and evolution in helium-rich low-mass stars
In this thesis we discuss many types of low mass stars linked by their unusually low hydrogen atmospheric abundance, usually completely replaced with helium. We begin with the hot subdwarfs; subdwarf
An abundance analysis of a chemically peculiar B star – JL 87
• Physics
• 2007
Aims. The aim of this study is to understand the nature and origin of a chemically peculiar star JL 87 by measuring its physical parameters and chemical abundances. Methods. Physical parameters –
Quantitative spectroscopy of extreme helium stars Model atmospheres and a non-LTE abundance analysis of BD+10°2179
• Physics
• 2017
Extreme helium stars (EHe stars) are hydrogen-deficient supergiants of spectral type A and B. They are believed to result from mergers in double degenerate systems. In this paper, we present a
Fe-bump instability: the excitation of pulsations in subdwarf B and other low-mass stars
• Physics
• 2006
We consider the excitation of radial and non-radial oscillations in low-mass B stars by the iron-bump opacity mechanism. The results are significant for the interpretation of pulsations in subdwarf B
Discovery of a variable lead-rich hot subdwarf: UVO 0825+15
• Physics
• 2017
UVO0825+15 is a hot bright helium-rich subdwarf which lies in {\it K2} Field 5 and in a sample of intermediate helium-rich subdwarfs observed with {\it Subaru/HDS}. The {\it K2} light curve shows
Merged white dwarfs and nucleosynthesis
• Physics
• 2020
Orbital decay mechanisms argue that double white dwarf mergers are inevitable, but extremely rare. Whilst some mergers result in explosions, the survivors re-ignite helium and burn brightly for tens
Blue large-amplitude pulsators as a new class of variable stars
• Physics, Geology
• 2017
A previously unidentified class of variable stars has been found in OGLE survey data, characterized by periodic brightness variations on ~30-min timescales, amplitudes of ~0.3 mag and temperatures of

## References

SHOWING 1-10 OF 16 REFERENCES
Non-linear radial pulsation models for the early-type helium stars V652 Her and BX Cir
• Physics
• 2002
We report new non-linear pulsation models of the helium stars V652 Her and BX Cir. Linear theory has previously shown their pulsations to be due to iron-group bump instability. Recent high-resolution
The pulsating hydrogen-deficient star LSS 3184 (BX Cir)
• Physics, Geology
• 1999
We present extensive photometry and spectroscopy of the extremely hydrogen-deficient star, LSS 3184, recently discovered to be a rapid variable (period ∼0.1066 d) strikingly similar to V652 Her. Over
Time-resolved spectral analysis of the pulsating helium star V652 Her
• Physics
• 2001
A series of 59 moderate-resolution high signal-to-noise spectra of the pulsating helium star V652 Her covering 1.06 pulsation cycles was obtained with the William Herschel Telescope. These have been
The evolution of a rapidly accreting helium white dwarf to become a low-luminosity helium star
• Physics
• 2000
We have examined the evolution of merged low-mass double white dwarfs which become low-luminosity (or high-gravity) extreme helium stars. We have approximated the merging process by the rapid
Abundance analyses of cool extreme helium stars
• Physics
• 2001
ABSTRA C T Extreme helium stars (EHes) with effective temperatures from 8000 to 13 000 K are among the coolest EHes and overlap the hotter R CrB stars in effective temperature. The cool EHes may
Double white dwarfs as progenitors of R Coronae Borealis stars and type I supernovae
Close double white dwarfs should arise from the second phase of mass exchagne in close binaries which first encountered mass exchange while the more massive star was crossing the Hertzprung gap.
On the evolution of those nuclei of planetary nebulae that experiencea final helium shell flash.
• Physics
• 1983
We suggest that some of the central stars of planetary nebulae experience a final thermal pulse having achieved a white dwarf configuration and begun their descent along a cooling white dwarf
Merged binary white dwarf evolution: rapidly accreting carbon–oxygen white dwarfs and the progeny of extreme helium stars
• Physics
• 2002
ABSTRA C T We have examined the evolution of merged low-mass double white dwarfs that become luminous helium stars. We have approximated the merging process by the rapid accretion of matter,
Automated spectroscopic abundances of A and F-type stars using echelle spectrographs - I. Reduction of ELODIE spectra and method of abundance determination
• Physics
• 2002
This paper presents an automated method to determine detailed abundances for A and F-type stars. This method is applied on spectra taken with the ELODIE spectrograph. Since the standard reduction
The pulsating extreme helium star BD+ 13°3224 II. Ultraviolet fluxes and effective temperature variations
• Physics
• 1984
Etude des variations de flux UV de l'etoile a helium extreme pulsante BD+13°3224. On determine les variations de temperature effective et de rayon angulaire sur un cycle en utilisant des modeles