IALP   13078
INSTITUTO DE ASTROFISICA LA PLATA
Unidad Ejecutora - UE
artículos
Título:
WR 110: A Single Wolf-Rayet Star with Corotating Interaction Regions in its Wind?
Autor/es:
CHENÉ, A.; MOFFAT, A. F. J.; CAMERON, C.; FAHED, R.; GAMEN, R. C.; LEFEVRE, L.; ROWE, J.F.; ST-LOUIS, N.; MUNTEAN, V.; DE LA CHEVROTIERE, A.; GUENTHER, D.B.; KUSCHNIG, R.; MATTHEWS, J.M.; RUCINSKI, S.M.; SASSELOV, D.; WEISS, W. W.
Revista:
ASTROPHYSICAL JOURNAL
Editorial:
IOP PUBLISHING LTD
Referencias:
Año: 2011 vol. 735 p. 34 - 43
ISSN:
0004-637X
Resumen:
A 30 day contiguous photometric run with the Microvariability and
Oscillations of STars (MOST) satellite on the WN5-6b star WR 110 (HD
165688) reveals a fundamental periodicity of P = 4.08 ± 0.55 days
along with a number of harmonics at periods P/n, with n ≈ 2, 3, 4, 5,
and 6, and a few other possible stray periodicities and/or stochastic
variability on timescales longer than about a day. Spectroscopic radial
velocity studies fail to reveal any plausible companion with a period in
this range. Therefore, we conjecture that the observed light-curve cusps
of amplitude ~0.01 mag that recur at a 4.08 day timescale may arise in
the inner parts, or at the base, of a corotating interaction region
(CIR) seen in emission as it rotates around with the star at constant
angular velocity. The hard X-ray component seen in WR 110 could then be
a result of a high velocity component of the CIR shock interacting with
the ambient wind at several stellar radii. Given that most hot, luminous
stars showing CIRs have two CIR arms, it is possible that either the
fundamental period is 8.2 days or, more likely in the case of WR 110,
there is indeed a second weaker CIR arm for P = 4.08 days, that occurs
~two-thirds of a rotation period after the main CIR. If this
interpretation is correct, WR 110 therefore joins the ranks with three
other single WR stars, all WN, with confirmed CIR rotation periods (WR
1, WR 6, and WR 134), albeit with WR 110 having by far the lowest
amplitude photometric modulation. This illustrates the power of being
able to secure intense, continuous high-precision photometry from
space-based platforms such as MOST. It also opens the door to revealing
low-amplitude photometric variations in other WN stars, where previous
attempts have failed. If all WN stars have CIRs at some level, this
could be important for revealing sources of magnetism or pulsation in
addition to rotation periods.