WASP-44b
Encyclopedia
WASP-44b is a closely orbiting Jupiter
-sized planet found in the orbit of the sunlike star WASP-44
by the SuperWASP
program, which searches for transiting planets that cross in front of their host stars as seen from Earth. After follow-up observations using radial 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 the Royal Astronomical Society
in May 2011.
, the SuperWASP
project searched the night sky for potential planets that transited, 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 the Cetus constellation between July and November 2009. In combination with later observations using both WASP-South and the SuperWASP-North in the Canary Islands, over 15,755 photometric
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. The star was observed at the same time as stars WASP-45 and WASP-46.
In 2010, the European team of astronomers used the CORALIE spectrograph
on the 1.2m Leonhard Euler Telescope
at Chile's La Silla Observatory
. The same radial velocity
measurements detected by SuperWASP were detected. The planet WASP-44b was confirmed after analysis of the results ruled out spectroscopic binary stars, leaving a transiting planet as the most likely cause of the radial velocity variations.
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.
The discovery of WASP-44b, along with those of WASP-45b and WASP-46b, were reported on May 16, 2011 by the Royal Astronomical Society
. The scientists who worked on the paper discussed the role of orbital 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).
es and a radius of 0.927 solar radii, which means that WASP-44 is 95% the mass of and 92% the size of the Sun. With an effective temperature
of 5410 K, WASP-44 is cooler than the Sun, although it is richer in iron, with a measured metallicity
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. Based on its spectrum, WASP-44 is not active in its chromosphere
(outer layer). The star was also not found to demonstrate a high rate of rotation.
With an apparent magnitude
of 12.9, WASP-44 cannot be seen with the unaided eye from Earth.
with a mass
of 0.889 times Jupiter's mass and a radius of 1.14 times that of Jupiter. 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. WASP-44b orbits at a mean distance of 0.03473 AU
, which is about 3% of the distance between the Earth and Sun. An orbit is completed every 2.4238039 days (58.171 hours).
WASP-44b has an orbital inclination of 86.02º, which is almost edge-on as seen from Earth.
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
-sized planet found in the orbit of the sunlike star WASP-44
WASP-44
WASP-44 is a G-type star in constellation Cetus that has the Jupiter-size planet WASP-44b in orbit. The star is slightly less massive and slightly smaller than the Sun; it is also slightly cooler, but is more metal-rich...
by the SuperWASP
SuperWASP
SuperWASP is an international academic organisation performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.-Equipment:...
program, which searches for transiting planets that cross in front of their host stars as seen from Earth. After follow-up observations using radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial 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 the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
in May 2011.
Discovery
Using the WASP-South station at the South African Astronomical ObservatorySouth African Astronomical Observatory
South African Astronomical Observatory is the national center for optical and infrared astronomy in South Africa. It was established in 1972. The observatory is run by the National Research Foundation of South Africa. The facility's function is to conduct research in astronomy and astrophysics...
, the SuperWASP
SuperWASP
SuperWASP is an international academic organisation performing an ultra-wide angle search for transiting extrasolar planets with the aim of covering the entire sky down to ~15th magnitude.-Equipment:...
project searched the night sky for potential planets that transited, 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 the Cetus constellation between July and November 2009. In combination with later observations using both WASP-South and the SuperWASP-North in the Canary Islands, over 15,755 photometric
Photometry
Photometry can refer to:* Photometry , the science of measurement of visible light in terms of its perceived brightness to human vision...
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. The star was observed at the same time as stars WASP-45 and WASP-46.
CORALIE spectrograph
The CORALIE spectrograph is an echelle type spectrograph used for astronomy. This instrument used with a telescope to measure star spectra for the Doppler effect to detect the presence of extrasolar planets by the radial velocity method...
on the 1.2m Leonhard Euler Telescope
Leonhard Euler Telescope
Leonhard Euler Telescope, or Swiss 1.2-m Leonhard Euler Telescope, is a diameter aperture reflecting telescope at the Geneva Observatory at La Silla Observatory. It is use for astronomy, and runs the CORALIE echelle spectrograph to search for planets. Its first planet discovery was of one in orbit...
at Chile's La Silla Observatory
La Silla Observatory
La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory organisation, and several others are partly maintained by ESO...
. The same radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...
measurements detected by SuperWASP were detected. The planet WASP-44b was confirmed after analysis of the results ruled out spectroscopic binary stars, leaving a transiting planet as the most likely cause of the radial velocity variations.
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.
The discovery of WASP-44b, along with those of WASP-45b and WASP-46b, were reported on May 16, 2011 by the Royal Astronomical Society
Royal Astronomical Society
The Royal Astronomical Society is a learned society that began as the Astronomical Society of London in 1820 to support astronomical research . It became the Royal Astronomical Society in 1831 on receiving its Royal Charter from William IV...
. The scientists who worked on the paper discussed the role of orbital eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
, 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).
Host star
WASP-44 is a sunlike G-type star in the Cetus constellation. WASP-44 has a mass of 0.951 solar massSolar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es and a radius of 0.927 solar radii, which means that WASP-44 is 95% the mass of and 92% the size of the Sun. With an effective temperature
Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation...
of 5410 K, WASP-44 is cooler than the Sun, although it is richer in iron, with a measured metallicity
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
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. Based on its spectrum, WASP-44 is not active in its chromosphere
Chromosphere
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep....
(outer layer). The star was also not found to demonstrate a high rate of rotation.
With an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of 12.9, WASP-44 cannot be seen with the unaided eye from Earth.
Characteristics
WASP-44b is a Hot JupiterHot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
with a mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
of 0.889 times Jupiter's mass and a radius of 1.14 times that of Jupiter. 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. WASP-44b orbits at a mean distance of 0.03473 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, which is about 3% of the distance between the Earth and Sun. An orbit is completed every 2.4238039 days (58.171 hours).
WASP-44b has an orbital inclination of 86.02º, which is almost edge-on as seen from Earth.