WASP-44b is a closely orbitingJupiter-sized planet found in the orbit of the sunlike starWASP-44 by theSuperWASP program, which searches fortransiting planets that cross in front of their host stars as seen from Earth. After follow-up observations usingradial velocity, the planet was confirmed. Use of another telescope at the same observatory detected WASP-44 transiting its star. The planet completes an orbit around its star every two and a half days, and orbits at roughly 0.03 AU from its host star. WASP-44b's discovery was reported by theRoyal Astronomical Society in May 2011.

Using the WASP-South station at theSouth African Astronomical Observatory, theSuperWASP project searched the night sky for potential planets thattransited, or crossed in front of, their host stars at a roughly periodic rate. WASP-44 was among the candidates identified as a possible host to a transit event. WASP-44's reclassification as a potential planetary host came about after WASP-South scanned theCetus constellation between July and November 2009. In combination with later observations using both WASP-South and the SuperWASP-North in the Canary Islands, over 15,755photometric measurements were collected. A later set of observations between August and November 2010 produced a 6,000 point photometric data set, but the light curve was prepared late and was not considered in the discovery paper.^[1] The star was observed at the same time as starsWASP-45 andWASP-46.^[1]

In 2010, the European team of astronomers used theCORALIE spectrograph on the 1.2mLeonhard Euler Telescope at Chile'sLa Silla Observatory. The sameradial velocity measurements detected by SuperWASP were detected. The planet WASP-44b was confirmed after analysis of the results ruled outspectroscopic binary stars, leaving a transiting planet as the most likely cause of the radial velocity variations.^[1]

The Euler telescope was used to observe WASP-44b as it transited its host star. For 4.2 hours on September 14, 2010, Euler observed WASP-44 in search of a slight dimming in brightness until a more precise light curve could be found. Accounting for all data yet collected, analysis yielded the planet's characteristics.^[1]

The discovery of WASP-44b, along with those ofWASP-45b andWASP-46b, were reported on May 16, 2011 by theRoyal Astronomical Society.^[1] The scientists who worked on the paper discussed the role oforbital eccentricity, or how elliptical an orbit is, and how poorly constrained it tends to be amongst Hot Jupiters, where a circular orbit is assumed. They used the three newly discovered planets as studies into the creation of a non-eccentric, circular model for a planet's orbit (the most likely solution) or an eccentric, elliptical solution for a planet's orbit (the solution that, according to the discovery team, required less of an assumption).^[1]

WASP-44 is a sunlikeG-type star in the Cetus constellation. WASP-44 has a mass of 0.951solar masses and a radius of 0.927solar radii, which means that WASP-44 is 95% the mass of and 92% the size of the Sun. With aneffective temperature of 5410K, WASP-44 is cooler than the Sun, although it is richer in iron, with a measuredmetallicity of [Fe/H] = 0.06 (1.15 times the amount of iron found in the Sun). The star is an estimated 900 million years old, although this age is uncertain, as error bars are large.^[2] Based on its spectrum, WASP-44 is not active in itschromosphere (outer layer). The star was also not found to demonstrate a high rate of rotation.^[1]

With anapparent magnitude of 12.9, WASP-44 cannot be seen with the unaided eye from Earth.^[2]

WASP-44b is aHot Jupiter^[1] with amass of 0.889 times Jupiter's mass and a radius of 1.002 timesthat of Jupiter.^[4] Although less massive than Jupiter, the planet is bloated to a greater size because its proximity to its host star heats it, a common effect in such closely orbiting gas giants.^[1] WASP-44b orbits at amean distance of 0.03473AU, which is about 3% of the distance between the Earth and Sun. An orbit is completed every 2.4238039 days (58.171 hours).^[2]

WASP-44b has anorbital inclination of 86.02º, which is almost edge-on as seen from Earth.^[2]

• Hot Jupiters
• Cetus
• Transiting exoplanets
• Exoplanets discovered in 2011
• Exoplanets discovered by WASP

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