2011A&A...528L..16G


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.18CET06:25:07

2011A&A...528L..16G - Astronomy and Astrophysics, volume 528, L16-16 (2011/4-1)

Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

GEIER S., NAPIWOTZKI R., HEBER U. and NELEMANS G.

Abstract (from CDS):

Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3d. Here we report the discovery of a low mass companion (M2>0.14M) orbiting the sdB star and central star of a planetary nebula EGB5 with an orbital period of 16.5d at a minimum separation of 23R. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution.

Abstract Copyright:

Journal keyword(s): binaries: spectroscopic - subdwarfs

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 PG 0057+155 HS* 00 59 56.6671977894 +15 44 13.737246975   12.02 12.32     sdB0.2VIIIpHe8 112 1
2 V* BN Mon C* 06 21 58.0010958225 +07 20 57.671759155   12.58 12.70     C4,3e 66 0
3 EGB 5 HS* 08 11 12.7659921835 +10 57 17.099261604     14.2     sdB 47 1
4 PG 0850+170 HS* 08 53 23.6574532327 +16 49 35.267448975   13.72 14.00 14.26   sdB 24 0
5 Ton 62 HS* 11 13 04.4869938454 +29 07 46.226753961   14.2 14.086     sdB 21 0
6 PG 1619+522 HS* 16 20 38.7298845239 +52 06 08.805926996   13.36       sdB0.5VIIHe7 28 0
7 JL 82 HS* 21 36 01.2956788748 -72 48 27.221376356 11.26 12.44 12.41 12.67   sdB 31 0

    Equat.    Gal    SGal    Ecl

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2019.11.18-06:25:07

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