He-accreting WDs: AM CVn stars with WD donors
نویسندگان
چکیده
منابع مشابه
AM CVn stars
I review our observational and theoretical knowledge of AM CVn stars, focusing on recent developments. These include newly discovered systems, the possibility that two recently discovered extremely short period objects are AM CVn stars and an update on X-ray, UV an optical studies. Theoretical advances include the study of the details of both the donor and accretor, and the physics of the heliu...
متن کاملThe outburst properties of AM CVn stars
We briefly summarize the observational properties of ultra-compact binaries called AM CVn stars. We analize their outbursts originating from the thermal-viscous instability in helium accretion disc. We present our preliminary results in applying the model of Dwarf Novae outbursts to helium discs. We can calculate models of outbursts of reasonable amplitude of 2 mag with a constant α parameter t...
متن کاملHst/fgs Parallaxes of Am Cvn Stars and Astrophysical Consequences
We present absolute parallaxes and relative proper motions for five AM CVn stars, which we obtained using the Fine Guidance Sensors on board the Hubble Space Telescope. Our parallax measurements translate into distances dAMCVn = 606 +135 −93 pc; dHPLib = 197 +14 −12 pc; dCRBoo = 337 +44 −35 pc; dV803Cen = 347 +32 −27 pc; and dGPCom = 75 +2 −2 pc. From these distances we estimate the space densi...
متن کاملAm Cvn Stars in the Uct Ccd Cv Survey
High speed photometry of the helium-transferring binary ES Cet – taken over a two-year period (2001 October – 2003 October) – shows a very stable photometric period of 620.211437 ± 0.000038 s, with a tentative indication of curvature in the O–C diagram suggesting a change in period at a rate of Ṗ ∼ 1.6×10 . Phase-resolved spectroscopy of ES Cet obtained with the Hobby-Eberly Telescope shows a c...
متن کاملThe chemical composition of donors in AM CVn stars and ultra-compact X-ray binaries: observational tests of their formation
We study the formation of ultra-compact binaries (AM CVn stars and ultra-compact X-ray binaries) with emphasis on the surface chemical abundances of the donors in these systems. Hydrogen is not convincingly detected in the spectra of any these systems. Three different proposed formation scenarios involve different donor stars, white dwarfs, helium stars or evolved main-sequence stars. Using det...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2015
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/stv1452