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Modeling Stellar Surface Features on a Subgiant Star with an M-dwarf Companion
Abstract Understanding magnetic activity on the surface of stars other than the Sun is important for exoplanet analyses to properly characterize an exoplanet’s atmosphere and to further characterize stellar activity on a wide range of stars. Modeling stellar surface features of a variety of spectral types and rotation rates is key to understanding the magnetic activity of these stars. Using data from Kepler, we use the starspot modeling program STarSPot ( STSP ) to measure the position and size of spots for KOI-340, which is an eclipsing binary consisting of a subgiant star ( T eff = 5593 ± 27 K, R ⋆ = 1.98 ± 0.05 R ⊙ ) with an M-dwarf companion ( M ⋆ = 0.214 ± 0.006 M ⊙ ). STSP uses a novel technique to measure the spot positions and radii by using the transiting secondary to study and model individual active regions on the stellar surface using high-precision photometry. We find that the average size of spot features on KOI-340's primary is ∼10% the radius of the star, i.e., two times larger than the mean size of solar-maximum sunspots. The spots on KOI-340 are present at every longitude and show possible signs of differential more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10351345
Journal Name:
The Astronomical Journal
Volume:
164
Issue:
1
Page Range or eLocation-ID:
14
ISSN:
0004-6256
National Science Foundation
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