HAT-P-4 b

AIMS

The transiting exoplanet HAT-P-4 b orbits a slightly evolved late F-type star every 3.07 d (Kovacs et al. 2007). It has a mass of 0.68 M_Jup and bloated radius of 1.27 R_Jup. These parameters make the planet challenging for models of the physical structure of hot Jupiters. Precise radial velocities show a long-term trend which could be caused by an additional body on a wide orbit, having a mass not smaller than 1.5 M_Jup (Knutson et al. 2014). The transit duration is about 4 hours that makes any follow-up observations challenging from the ground because there are few observing windows with complete transits available in a given site each year. In the discovery paper (Kovacs et al. 2007), there are one complete and one partial high-quality light curves. Winn et al. (2010) report only two new and incomplete light curves. The system was observed by the NASA EPOXI Mission of Opportunity and 10 complete light curves were obtained (Christiansen et al. 2011). Interestingly, the orbital period determined from space-based observations differs by more than 3 sigma from the value derived by Sada et al. (2012) who acquired a single light curve in a J band from the ground. These authors also find the transit duration shorter by 10 minutes from previous determinations. That results in smaller values of an orbital inclination and scaled semimajor axis.

We propose to obtain new, high-precision transit light curves for HAT-P-4 b in 2015 in order to refine system parameters and search for any sign of their variation.

RESULTS

No conclusive results so far. More observations needed.

STATUS

The campaign is extended until 2018. Only high-quality data (>1 m mirrors) in filters are needed (please do not use a clear filter)

LIGHT CURVES

No. Date Instrument Comment
1 2010 Apr 01 UH 2.2 m partial
2 2015 May 06 OSN 1.5 m
3 2016 Mar 28 OSN 1.5 m
4 2017 May 30 OSN 0.9 m partial

CONTACT

PI: Gracjan Maciejewski gmac@umk.pl

 
hat4.txt · Last modified: 2017/06/07 09:45 by Gracjan Maciejewski
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