2008A&A...483..585V

Query : 2008A&A...483..585V

2008A&A...483..585V - Astronomy and Astrophysics, volume 483, 585-590 (2008/5-4)

Non-thermal radio emission from O-type stars. III. Is Cygnus OB2 No. 9 a wind-colliding binary?

VAN LOO S., BLOMME R., DOUGHERTY S.M. and RUNACRES M.C.

Abstract (from CDS):

The star Cyg OB2 No. 9 is a well-known non-thermal radio emitter. Recent theoretical work suggests that all such O-stars should be in a binary or a multiple system. However, there is no spectroscopic evidence of a binary component. Re-analysis of radio observations from the VLA of this system over 25 years has revealed that the non-thermal emission varies with a period of 2.35±0.02yr. This is interpreted as a strong suggestion of a binary system, with the non-thermal emission arising in a wind-collision region. We derived some preliminary orbital parameters for this putative binary and revised the mass-loss rate of the primary star downward from previous estimates.

Abstract Copyright: ∼

Journal keyword(s): stars: individual: Cyg OB2 No. 9 - stars: early-type - stars: mass-loss - radiation mechanisms: non-thermal

CDS comments: Table A1 : Notes : Several sources not identified.

Simbad objects: 11

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Number of rows : 11
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 RX J015720.8+375632 X 01 57 20.9 +37 56 32           ~ 2 0
2 V* V712 Car EB* 10 23 58.0126366512 -57 45 48.937268268 15.466 15.473 13.5 12.6   O3If*/WN6+O3If*/WN6 171 1
3 QSO B2005+40 QSO 20 07 44.9449261536 +40 29 48.603352020   18.5 19.00 20.3   ~ 301 1
4 HD 193793 WR* 20 20 27.9757908696 +43 51 16.286840244 6.90 7.25 6.85 4.58   WC7pd+O5.5fc 710 0
5 BD+40 4212 SB* 20 31 37.5053189952 +41 13 21.001757520 12.46 11.5 10.214     O6IV:+O9III 79 1
6 BD+40 4220 s*b 20 32 22.4238071594 +41 18 18.942475904 11.32 10.61 9.185     O7Iafep 399 0
7 V* V1521 Cyg HXB 20 32 25.78 +40 57 27.9           WN4/5-6/7 1939 2
8 Schulte 9 s*b 20 33 10.7362926720 +41 15 08.222370372 13.38 12.77 10.96     O5I+O4III 232 0
9 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 943 0
10 BD+40 4227A SB* 20 33 15.0781182864 +41 18 50.479292556 10.42 10.27 8.98 8.03 6.83 O6Ib(fc)+O4.5:III:(fc) 246 0
11 EM* AS 431 WR* 20 36 43.6322747712 +40 21 07.442607924     13.73 12.51   WN8(h)+B0.5V 220 0

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