DYNAMICAL CONSTRAINTS ON THE CORE MASS OF HOT JUPITER HAT-P-13B

作者：Buhler Peter B^*; Knutson Heather A; Batygin Konstantin; Fulton Benjamin J; Fortney Jonathan J; Burrows Adam; Wong Ian

来源：Astrophysical Journal, 2016, 821(1): 26.

DOI：10.3847/0004-637X/821/1/26

• data analysis
• planets and satellites: atmospheres
• planets and satellites: dynamical evolution and stability
• planets and satellites: individual (HAT-P-13b)
• planets and satellites: interiors
• techniques: photometric

HAT-P-13b is a Jupiter-mass transiting exoplanet that has settled onto a stable, short-period, and mildly eccentric orbit as a consequence of the action of tidal dissipation and perturbations from a second, highly eccentric, outer companion. Owing. to the special orbital configuration of the HAT-P-13 system, the magnitude of HAT-P-13b's eccentricity (e(b)) is in part dictated by its Love number (k(2b)), which is in turn a proxy for the degree of central mass concentration in its interior. Thus, the measurement of eb constrains k2b and allows us to place otherwise elusive constraints on the mass of HAT-P-13b's core (M-core,M-b). In this study we derive new constraints on the value of eb by observing two secondary eclipses of HAT-P-13b with the Infrared Array Camera on board the Spitzer Space Telescope. We fit the measured secondary eclipse times simultaneously with radial velocity measurements and find that e(b) = 0.00700 +/- 0.00100. We then use octupole-order secular perturbation theory to find the corresponding k(2b) = 0.31(-0.05)(+0.08). Applying structural evolution models, we then find, with 68% confidence, that M-core,M-b is less than 25 Earth masses (M circle plus). The most likely value is. M-core,M-b = 11M circle plus, which is similar to the core mass theoretically required for runaway gas accretion. This is the tightest constraint to date on the core mass of a hot Jupiter. Additionally, we find that the measured secondary eclipse depths, which are in the 3.6 and 4.5 mu m bands, best match atmospheric model predictions with a dayside temperature inversion and relatively efficient day-night circulation.

• 出版日期2016-4-10