WASP-28b

WASP-28b or K2-1b is an extrasolar planet discovered in 2010^[4] by the Wide Angle Search for Planets (WASP) project orbiting WASP-28, a magnitude 12 star also known as 1SWASP J233427.87-013448.1, 2MASS J23342787-0134482 and K2-1.^[5][1] Since it orbits its star very closely, the planet is a strongly irradiated hot Jupiter.^[1] As seen from the Earth, WASP-28b transits its host star every 3.41 days taking about 3 hours to do so.^[1]

WASP-28b

Size comparison of WASP-28b with Jupiter.
Discovery[1]
Discovered by	Wide Angle Search for Planets
Discovery date	2010
Detection method	Transit
Orbital characteristics
Semi-major axis	0.0442±0.0010 AU
Eccentricity	<0.075[2]
Orbital period (sidereal)	3.40883495±0.00000015[2] d
Inclination	88.61 ± 0.67[1]
Star	WASP-28
Physical characteristics
Mean radius	1.319+0.028 −0.026[3] RJ
Mass	0.948+0.051 −0.052[3] MJ
Temperature	1468 ± 37[1] K

The planet was observed by the Kepler space telescope during the K2 mission engineering campaign in February 2014 as part of an early science demonstration.^[6] It was also observed from December 2016 to March 2017 during K2's campaign 12 which allowed a refinement of the system parameters.^[2]

Internal structure

The planet seems to be a gas giant with a low core mass (<~10M(Earth)) and a low heavy elements content (Z<~0.2).^[1]