Modeling the Rossiter-McLaughlin effect: impact of the convective center-to-limb variations in the stellar photosphere

Cegla, H. M., Oshagh, M., Watson, C. A., Figueira, P., Santos, N. C. and Shelyag, S. 2016, Modeling the Rossiter-McLaughlin effect: impact of the convective center-to-limb variations in the stellar photosphere, Astrophysical journal, vol. 819, no. 1, doi: 10.3847/0004-637X/819/1/67.

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Title Modeling the Rossiter-McLaughlin effect: impact of the convective center-to-limb variations in the stellar photosphere
Author(s) Cegla, H. M.
Oshagh, M.
Watson, C. A.
Figueira, P.
Santos, N. C.
Shelyag, S.ORCID iD for Shelyag, S.
Journal name Astrophysical journal
Volume number 819
Issue number 1
Total pages 12
Publisher IOP Publishing
Place of publication Bristol, Eng.
Publication date 2016-03-01
ISSN 0004-637X
Keyword(s) Science & Technology
Physical Sciences
Astronomy & Astrophysics
line: profiles
planets and satellites: detection
stars: activity
stars: low-mass
Sun: granulation
techniques: radial velocities
Summary © 2016. The American Astronomical Society. All rights reserved. Observations of the Rossiter-McLaughlin (RM) effect provide information on star-planet alignments, which can inform planetary migration and evolution theories. Here, we go beyond the classical RM modeling and explore the impact of a convective blueshift that varies across the stellar disk and non-Gaussian stellar photospheric profiles. We simulated an aligned hot Jupiter with a four-day orbit about a Sun-like star and injected center-to-limb velocity (and profile shape) variations based on radiative 3D magnetohydrodynamic simulations of solar surface convection. The residuals between our modeling and classical RM modeling were dependent on the intrinsic profile width and v sin i; the amplitude of the residuals increased with increasing v sin i and with decreasing intrinsic profile width. For slowly rotating stars the center-to-limb convective variation dominated the residuals (with amplitudes of 10 s of cm s-1 to ∼1 m s-1); however, for faster rotating stars the dominant residual signature was due a non-Gaussian intrinsic profile (with amplitudes from 0.5 to 9 m s-1). When the impact factor was 0, neglecting to account for the convective center-to-limb variation led to an uncertainty in the obliquity of ∼10°-20°, even though the true v sin i was known. Additionally, neglecting to properly model an asymmetric intrinsic profile had a greater impact for more rapidly rotating stars (e.g., v sin i = 6 km s-1) and caused systematic errors on the order of ∼20° in the measured obliquities. Hence, neglecting the impact of stellar surface convection may bias star-planet alignment measurements and consequently theories on planetary migration and evolution.
Language eng
DOI 10.3847/0004-637X/819/1/67
Field of Research 0201 Astronomical And Space Sciences
0305 Organic Chemistry
0306 Physical Chemistry (Incl. Structural)
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2016, The American Astronomical Society.
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