S. C. -L. Hu, W. P. Chen, the Young Exoplanet Transit Initiative Collaboration
We present our photometric observations of GM Cep, a solar type variable in
the young (~4 Myr) open cluster Trumpler 37. The star is known as a classical T
Tauri star with a circumstellar disk and active accretion. GM\,Cep was
suspected to undergo an outburst, thus a candidate for an EXor-type variable.
In our monitoring campaign observations in 2010-2011, GM Cep experienced a
~0.82 mag brightness decrease in the R band lasting for 39 days, and frequent,
transient flare-like episodes with amplitude < 1 mag, each lasting for about 10
days. The brightening was accompanied with a bluer color, presumably arising
from increased accretion activity. Interestingly, the star also turned bluer in
the fading phase. Combining the AAVSO and literature data, we found a
quasi-cyclic peroid of ~311 days for the fading event. A possible mechanism for
the fading could be obscuration by a clump of dust around the star. We proposed
that GM Cep therefore should be a UXor-type variable in the transition phase
between grain coagulation and planetesimal formation process in the
circumstellar disk.
View original:
http://arxiv.org/abs/1202.5084
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