NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Kepler and Ground-Based Transits of the exo-Neptune HAT-P-11bWe analyze 26 archival Kepler transits of the exo-Neptune HAT-P-11b, supplemented by ground-based transits observed in the blue (B band) and near-IR (J band). Both the planet and host star are smaller than previously believed; our analysis yields Rp = 4.31 R xor 0.06 R xor and Rs = 0.683 R solar mass 0.009 R solar mass, both about 3 sigma smaller than the discovery values. Our ground-based transit data at wavelengths bracketing the Kepler bandpass serve to check the wavelength dependence of stellar limb darkening, and the J-band transit provides a precise and independent constraint on the transit duration. Both the limb darkening and transit duration from our ground-based data are consistent with the new Kepler values for the system parameters. Our smaller radius for the planet implies that its gaseous envelope can be less extensive than previously believed, being very similar to the H-He envelope of GJ 436b and Kepler-4b. HAT-P-11 is an active star, and signatures of star spot crossings are ubiquitous in the Kepler transit data. We develop and apply a methodology to correct the planetary radius for the presence of both crossed and uncrossed star spots. Star spot crossings are concentrated at phases 0.002 and +0.006. This is consistent with inferences from Rossiter-McLaughlin measurements that the planet transits nearly perpendicular to the stellar equator. We identify the dominant phases of star spot crossings with active latitudes on the star, and infer that the stellar rotational pole is inclined at about 12 deg 5 deg to the plane of the sky. We point out that precise transit measurements over long durations could in principle allow us to construct a stellar Butterfly diagram to probe the cyclic evolution of magnetic activity on this active K-dwarf star.
Document ID
20120002324
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Deming, Drake
(Maryland Univ. College Park, MD, United States)
Sada, Pedro V.
(Kitt Peak National Observatory Tucson, AZ, United States)
Jackson, Brian
(Kitt Peak National Observatory Tucson, AZ, United States)
Peterson, Steven W.
(Kitt Peak National Observatory Tucson, AZ, United States)
Agol, Eric
(California Univ. Berkeley, CA, United States)
Knutson, Heather A.
(California Univ. Berkeley, CA, United States)
Jennings, Donald E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Haase, Plynn
(Kitt Peak National Observatory Tucson, AZ, United States)
Bays, Kevin
(Kitt Peak National Observatory Tucson, AZ, United States)
Date Acquired
August 25, 2013
Publication Date
October 10, 2011
Publication Information
Publication: The Astrophysical Journal
Volume: 740
Issue: 1
Subject Category
Astronomy
Report/Patent Number
GSFC.JA.5558.2011
Funding Number(s)
CONTRACT_GRANT: NSF AST-0645416
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available