Bibcode
Gillen, E.; Aigrain, S.; Terquem, C.; Bouvier, J.; Alencar, S. H. P.; Gandolfi, D.; Stauffer, J.; Cody, A.; Venuti, L.; Almeida, P. Viana; Micela, G.; Favata, F.; Deeg, H. J.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 599, id.A27, 18 pp.
Fecha de publicación:
2
2017
Revista
Número de citas
11
Número de citas referidas
10
Descripción
CoRoT 223992193 is the only known low-mass, pre-main sequence eclipsing
binary that shows evidence of a circumbinary disk. The system displays
complex photometric and spectroscopic variability over a range of
timescales and wavelengths. Using two optical CoRoT runs from 2008 and
2011/2012 (spanning 23 and 39 days), along with infrared Spitzer 3.6 and
4.5 μm observations (spanning 21 and 29 days, and simultaneous with
the second CoRoT run), we model the out-of-eclipse light curves, finding
that the large scale structure in both CoRoT light curves is consistent
with the constructive and destructive interference of starspot signals
at two slightly different periods. Using the vsini of both stars, we
interpret this as the two stars having slightly different rotation
periods: the primary is consistent with synchronisation and the
secondary rotates slightly supersynchronously. Comparison of the raw
2011/2012 light curve data to the residuals of our spot model in
colour-magnitude space indicates additional contributions consistent
with a combination of variable dust emission and obscuration. There
appears to be a tentative correlation between this additional
variability and the binary orbital phase, with the system displaying
increases in its infrared flux around primary and secondary eclipse. We
also identify short-duration flux dips preceding secondary eclipse in
all three CoRoT and Spitzer bands. We construct a model of the inner
regions of the binary and propose that these dips could be caused by
partial occultation of the central binary by the accretion stream onto
the primary star. Analysis of 15 Hα profiles obtained with the
FLAMES instrument on the Very Large Telescope reveal an emission profile
associated with each star. The majority of this is consistent with
chromospheric emission but additional higher velocity emission is also
seen, which could be due to prominences. However, half of the secondary
star's emission profiles display full widths at 10% intensity that could
also be interpreted as having an accretion-related origin. In addition,
simultaneous u and r-band observations obtained with the MEGACam
instrument on the Canada France Hawaii Telescope reveal a short-lived
u-band excess consistent with either an accretion hot spot or stellar
flare. The photometric and spectroscopic variations are very complex but
are consistent with the picture of two active stars possibly undergoing
non-steady, low-level accretion; the system's very high inclination
provides a new view of such variability.
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Savita
Mathur