2017MNRAS.465.1227D


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.18CEST16:04:42

2017MNRAS.465.1227D - Mon. Not. R. Astron. Soc., 465, 1227-1240 (2017/February-2)

The spectral variability of a sample of WC 9 stars on time-scales of days to weeks.

DESFORGES S., ST-LOUIS N., CHENE A.-N., DE LA CHEVROTIERE A. and HENAULT-BRUNET V.

Abstract (from CDS):

We present the results of a spectroscopic monitoring campaign of nine presumably single Wolf-Rayet (WR) stars, eight of type WC 9 and one WC 8d. We characterize their variability and search for clues to the mechanism responsible for the formation of dust in their wind. For seven out of eight WC 9s, we find a large-scale line-flux variability level of σ > 5-8 per cent. The only WC 8d star is variable at a level more comparable with those associated with wind clumping, σ = 2.2 per cent. The changes take place on a time-scale of days but in many cases, observing over longer time spans resulted in higher line-flux variability levels. The width of the substructures ranges from ∼150 to 300 km s–1, with the widest structures corresponding to stars with the highest variability amplitude. We searched for periodicities in integrated line quantities for C III λ5696. Radial velocity changes are typically ∼20 km s–1 but never exceed 40 km s–1 and are anticorrelated with the skewness of the line, strongly suggesting that they do not correspond to a real movement of the star. No periodicity was found in these integrated quantities, except for WR 103. Therefore, a wind-wind collision in a close binary does not seem to be responsible for the short-term variability. We cannot, however, exclude that these stars are intermediate- to long-period binaries. We estimate that for periods up to a few years, the shock-cone resulting from wind collisions would be non-adiabatic and thus unstable. We suggest that this represents a viable mechanism to explain the spectroscopic variability.

Abstract Copyright:

Journal keyword(s): techniques: spectroscopic - stars: winds - outflows - stars: Wolf-Rayet - stars: Wolf-Rayet

VizieR on-line data: <Available at CDS (J/MNRAS/465/1227): table1.dat table3.dat table4.dat>

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 4004 WR* 00 43 28.3971235391 +64 45 35.383738645 10.28 10.718 10.138     WN4-s 187 0
2 HD 6327 WR* 01 05 23.0143603 +60 25 18.965197   11.49 11.33     WN2-w 114 0
3 HD 50896 WR* 06 54 13.0440847499 -23 55 42.020318514 5.74 6.63 6.91 7.74   WN4b 749 0
4 HD 117297 WR* 13 30 53.2511996037 -62 04 51.856386987 10.81 11.10 10.90 10.70   WC8 92 0
5 HD 136488 WR* 15 24 11.3111665819 -62 40 37.575311536 9.15 9.514 9.10 9.71   WC9d+OB? 115 0
6 HD 137603 WR* 15 29 44.6908093554 -58 34 51.248928169 10.98 10.95 9.71 9.78   WC9+OB 105 0
7 MR 66 WR* 17 02 40.3825863866 -45 59 15.455194984   13.62 12.07 11.77   WC9 61 0
8 CPD-33 4347 WR* 17 18 49.7246525731 -33 57 41.389875461   13.93 12.56 12.21   WN8/WC9 63 0
9 HD 157451 WR* 17 25 23.2779746024 -43 29 31.469615959 10 10.59 10.20 10.46   WC9 85 0
10 WR 98a WR* 17 41 13.0431655551 -30 32 30.425152324   18.40   15.20 13.82 WC8/9 94 1
11 HD 164270 WR* 18 01 43.1452971756 -32 42 55.161881733 8.52 8.97 8.74 9.51   WC9d+? 219 0
12 MR 80 WR* 18 02 04.1238716757 -23 37 42.144766363   14.85       WC9 214 2
13 HD 313643 WR* 18 04 43.6647304100 -21 09 30.557213987 13.58 13.27 12.02 11.67   WC9d 89 0
14 THA 20-1 WR* 18 39 17.9036019736 -10 05 30.898511525   13.07 12.43     WC9d 53 0
15 EM* AS 320 WR* 18 44 13.1527220304 -03 47 57.779718279 13.7 13.340 13.983     WC9d 114 0
16 HD 191765 WR* 20 10 14.1929815789 +36 10 35.069005168 7.64 8.08 8.08     WN6-s 429 0
17 HD 193793 WR* 20 20 27.9763345925 +43 51 16.289775091 6.90 7.25 6.85 4.58   WC7p+O5 663 1

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2021.05.18-16:04:42

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