2011MNRAS.418.1156M

Query : 2011MNRAS.418.1156M

2011MNRAS.418.1156M - Mon. Not. R. Astron. Soc., 418, 1156-1164 (2011/December-1)

Discovery of a stripped red giant core in a bright eclipsing binary system.

MAXTED P.F.L., ANDERSON D.R., BURLEIGH M.R., COLLIER CAMERON A., HEBER U., GANSICKE B.T., GEIER S., KUPFER T., MARSH T.R., NELEMANS G., O'TOOLE S.J., OSTENSEN R.H., SMALLEY B. and WEST R.G.

Abstract (from CDS):

We have identified a star in the Wide Angle Search for Planets (WASP) archive photometry with an unusual light curve due to the total eclipse of a small, hot star by an apparently normal A-type star and with an orbital period of only 0.668 d. From an analysis of the WASP light curve together with V-band and I_C-band photometry of the eclipse and a spectroscopic orbit for the A-type star we estimate that the companion star has a mass of 0.23±0.03 M_☉ and a radius of 0.33±0.01 R_☉, assuming that the A-type star is a main-sequence star with the metallicity appropriate for a thick-disc star. The effective temperature of the companion is 13 400 ±1200 K from which we infer a luminosity of 3±1 L_☉. From a comparison of these parameters to various models we conclude that the companion is most likely to be the remnant of a red giant star that has been very recently stripped of its outer layers by mass transfer on to the A-type star. In this scenario, the companion is currently in a shell hydrogen-burning phase of its evolution, evolving at nearly constant luminosity to hotter effective temperatures prior to ceasing hydrogen burning and fading to become a low-mass white dwarf composed of helium (He-WD). The system will then resemble the pre-He-WD/He-WD companions to A- and B-type stars recently identified from their Kepler satellite light curves (KOI-74, KOI-81 and KIC 10657664). This newly discovered binary offers the opportunity to study the evolution of a stripped red giant star through the pre-He-WD stage in great detail.

Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 084.D-0348(A).

Abstract Copyright: 2011 The Authors Monthly Notices of the Royal Astronomical Society2011 RAS

Journal keyword(s): binaries: close - binaries: eclipsing - binaries: spectroscopic - stars: individual: 1SWASP J024743.37-251549.2 - stars: peculiar

CDS comments: V209 ome Cen = Cl* NGC 5139 SAW V209, PC1-V36 = Cl* NGC 104 EGG V36, V46 = [KTK97] V46

Simbad objects: 13

Full paper

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Number of rows : 13

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Mag U	Mag B	Mag V	Mag R	Mag I	Sp type	#ref 1850 - 2026	#notes
1	NGC 104	GlC	00 24 05.359	-72 04 53.20			4.09			~	4158	0
2	Cl* NGC 104 MAM M58539	EB*	00 24 06.2184	-72 04 52.168	17.9	17.76	17.71		17.81	~	9	0
3	1SWASP J024743.37-251549.2	EB*	02 47 43.3843773672	-25 15 49.269532545		12.381	12.231	12.397		~	52	0
4	* alf Leo	PM*	10 08 22.31099	+11 58 01.9516	0.88	1.24	1.40	1.37	1.47	B8IVn	891	1
5	Cl* NGC 5139 SAW V209	BS*	13 26 17.2590081384	-47 23 17.168879292	16.915	16.721	16.578	16.566	16.364	~	21	0
6	NGC 5139	GlC	13 26 47.28	-47 28 46.1						~	3677	0
7	M 4	GlC	16 23 35.22	-26 31 32.7						~	1978	0
8	[KTK97] V46	HS*	16 23 47.19	-26 31 56.5	18.85	18.85	18.58	18.39	18.16	sdB	20	0
9	* ome Oph	a2*	16 32 08.2003815598	-21 27 59.052127058	4.69	4.56	4.45	4.32	4.30	ApSrEuCr	167	0
10	KOI-964	EB*	19 13 59.8696461528	+47 59 47.244395688						~	50	0
11	KOI-81	EB*	19 35 08.5764186408	+45 01 06.455313660		11.51	11.32			B8V	60	0
12	KOI-74	EB*	19 53 17.8104467976	+42 23 18.509696700		10.832	10.896	10.976		A1V	68	1
13	HD 188112	HS*	19 54 31.4191828536	-28 20 20.679710640		10.01	10.22			sdB	101	0

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