KELT-2Ab: A Hot Jupiter Transiting the Bright (V=8.77) Primary Star of a Binary System

(Submitted on 7 Jun 2012)

We report the discovery of KELT-2Ab, a hot Jupiter transiting the bright (V=8.77) primary star of the HD 42176 binary system. The host is a slightly evolved late F-star likely in the very short-lived "blue-hook" stage of evolution, with $\teff=6151\pm50{\rm K}$, $\log{g_*}=4.030_{-0.028}^{+0.013}$ and $\feh=-0.018\pm0.069$. The inferred stellar mass is $M_*=1.308_{-0.025}^{+0.028}$\msun\ and the star has a relatively large radius of $R_*=1.828_{-0.034}^{+0.070}$\rsun. The planet is a typical hot Jupiter with period $4.113791\pm0.00001$ days and a mass of $M_P=1.522\pm0.078$\mj\ and radius of $R_P=1.286_{-0.047}^{+0.065}$\rj. This is mildly inflated as compared to models of irradiated giant planets at the $\sim$4 Gyr age of the system. KELT-2A is the third brightest star with a transiting planet identified by ground-based transit surveys, and the ninth brightest star overall with a transiting planet. KELT-2Ab's mass and radius are unique among the subset of planets with $V<9$ host stars, and therefore increases the diversity of bright benchmark systems. We also measure the relative motion of KELT-2A and -2B over a baseline of 38 years, robustly demonstrating for the first time that the stars are bound. This allows us to infer that KELT-2B is an early K dwarf. We hypothesize that through the eccentric Kozai mechanism KELT-2B may have emplaced KELT-2Ab in its current orbit. This scenario is potentially testable with Rossiter-McLaughlin measurements, which should have an amplitude of $\sim$44 m s$^{-1}$.
http://arxiv.org/abs/1206.1592

Planet : KELT-2A b

THE PLANET

- Basic data :

Name	KELT-2A b
Discovered in	2012
M.sin i	1.486 (± 0.088) M_J	ref.
Semi major axis	0.05498 (± 0.0004) AU	ref.
Orbital period	4.1137914 (± 1e-05) days	ref.
Eccentricity	0.185 (± 0.08)	ref.
ω	160 (± 110) deg.	ref.
Radius	1.306 (_−0.067^+0.081) R_J	ref.
T_transit	2455974.60356 (± 0.00084)	ref.
T_peri	2455974.83 (± 1.2)	ref.
Update	11/06/12

- No molecule detected

THE STAR

- Basic data :

- More data :
	- Basic data (from Simbad) - Most recent ref (from ADS)

- Remarks :
	Alias HD 42176 Member of a 2 arcsec wide binary star system.

Name	KELT-2A
Distance	128.9 (_−8.8^+6.9) pc	ref.
Spectral Type	F7V
Apparent Magnitude V	8.7
Mass	1.31 (± 0.03) M_sun	ref.
Effective Temperature	6148 (± 49) K	ref.
Radius	1.842 (_−0.071^+0.095) R_sun	ref.
Metallicity [Fe/H]	-0.015 (± 0.071)	ref.
Right Asc. Coord.	06 10 39
Decl. Coord.	+30 57 26

http://exoplanet.eu/planet.php?p1=KELT-2A&p2=b
HD 42176
Созвездие:Возничий
Каталоги и обозначения:
Собственные     (Edit)
имена:
HD 1989     HD 42176
TYCHO-2 2000    TYC 2420-899-1
USNO-A2.0    USNO-A2 1200-04436596
HIP            HIP 29301
http://www.skymap2.sky-map.org/starview?object_type=1&object_id=570159&object_name=HD+42176