2005A&A...436.1033B


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.13CET14:58:38

2005A&A...436.1033B - Astronomy and Astrophysics, volume 436, 1033-1040 (2005/6-4)

Non-thermal radio emission from O-type stars. I. HD 168112.

BLOMME R., VAN LOO S., DE BECKER M., RAUW G., RUNACRES M.C., SETIA GUNAWAN D.Y.A. and CHAPMAN J.M.

Abstract (from CDS):

We present a radio lightcurve of the O5.5 III(f+) star HD 168112, based on archive data from the Very Large Array (VLA) and the Australia Telescope Compact Array (ATCA). The fluxes show considerable variability and a negative spectral index, thereby confirming that HD 168112 is a non-thermal radio emitter. The non-thermal radio emission is believed to be due to synchrotron radiation from relativistic electrons that have been Fermi accelerated in shocks. For HD 168112, it is not known whether these shocks are due to a wind-wind collision in a binary system or to the intrinsic instability of the stellar wind driving mechanism. Assuming HD 168112 to be a single star, our synchrotron model shows that the velocity jump of the shocks should be very high, or there should be a very large number of shocks in the wind. Neither of these is compatible with time-dependent hydrodynamical calculations of O star winds. If, on the other hand, we assume that HD 168112 is a binary, the high velocity jump is easily explained by ascribing it to the wind-wind collision. By further assuming the star to be an eccentric binary, we can explain the observed radio variability by the colliding-wind region moving in and out of the region where free-free absorption is important. The radio data presented here show that the binary has a period of between one and two years. By combining the radio data with X-ray data, we find that the most likely period is ∼1.4yr.

Abstract Copyright:

Journal keyword(s): stars: individual: HD 168112 - stars: early-type - stars: mass-loss - stars: winds, outflows - radio continuum: stars - radiation mechanisms: non-thermal

Simbad objects: 22

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Number of rows : 22

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 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2441 2
2 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3630 1
3 QSO B1730-130 QSO 17 33 02.70578476 -13 04 49.5481484   18 18.5 18.78   ~ 960 1
4 QSO B1741-038 QSO 17 43 58.85613396 -03 50 04.6166450     18.5 17.98   ~ 467 1
5 * 9 Sgr Em* 18 03 52.4455370104 -24 21 38.639393923 5.08 5.97 5.97 5.72 5.70 O4V((f))z 511 0
6 NVSS J181106-205503 Rad 18 11 06.79427 -20 55 03.2781           ~ 13 1
7 Ass Ser OB 2 As* 18 18 -12.3           ~ 56 0
8 NGC 6604 OpC 18 18 03 -12 14.5   7.06 6.5     ~ 116 1
9 HD 167971 s*b 18 18 05.8954978252 -12 14 33.324312346 7.89 8.27 7.50 6.68 6.279 O8Iaf(n)+O4/5 269 0
10 GPSR 018.565+1.756 Rad 18 18 26.67 -11 55 57.3           ~ 2 0
11 HD 168112 ** 18 18 40.8671023267 -12 06 23.366098112 8.81 9.21 8.52 9.24   O5III(f) 134 0
12 OHIO U -033 Rad 18 22 28.5 -09 38 53           ~ 16 0
13 ICRF J182931.7+484446 Sy1 18 29 31.7812801678 +48 44 46.158815781   17.05 16.81 16.860   ~ 619 1
14 ICRF J183220.8-103511 G 18 32 20.83647 -10 35 11.1968           ~ 65 1
15 QSO B1830-211 QSO 18 33 39.92 -21 03 39.9     18.70 21   ~ 538 6
16 PMN J1834-1237 Rad 18 34 19.30 -12 37 41.0           ~ 10 1
17 QSO B1908-202 QSO 19 11 09.65289198 -20 06 55.1089891   18.21   18.14   ~ 230 0
18 ICRF J193925.0-634245 Sy2 19 39 25.02671 -63 42 45.6255   18.87 18.37 17.64   ~ 925 1
19 HD 193793 WR* 20 20 27.9763345925 +43 51 16.289775091 6.90 7.25 6.85 4.58   WC7p+O5 641 1
20 BD+40 4220 EB* 20 32 22.4241357648 +41 18 18.942382590 11.32 10.79 9.185     O6.5-7f+O5.5-6f 366 0
21 Schulte 9 s*b 20 33 10.7366753544 +41 15 08.222187463 13.38 12.77 10.96     O4.5If 201 0
22 EM* AS 431 WR* 20 36 43.6 +40 21 08   17.04 14.89     WN8(h)+B0.5V 201 2

    Equat.    Gal    SGal    Ecl

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2019.12.13-14:58:38

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