WASP-44
Encyclopedia
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. The star was observed by SuperWASP
, an organization in search of planets, starting in 2009; manual follow-up observations used WASP-44's spectrum
and measurements of its radial velocity
led to the discovery of the transiting planet WASP-44b. The planet and its star were presented along with WASP-45b and WASP-46b on May 17, 2011 by a team of scientists testing the idea that Hot Jupiters tend to have circular orbits, an assumption that is made when the orbital eccentricity
of such planets are not well-constrained.
planet-searching program based at the South African Astronomical Observatory
. Observations of the star revealed a periodic decrease in its brightness. WASP-South, along with the SuperWASP-North station at the Roque de los Muchachos Observatory
on the Canary Islands, collected 15,755 photometric
observations, allowing scientists to produce a more accurate light curve
. Another set of observations yielded a 6,000 point photometric data set, but the light curve was prepared late and was not considered in the discovery paper.
In 2010, a European science team investigated the star using the CORALIE spectrograph
and collected seventeen spectra
of WASP-44. From the spectra, radial velocity
measurements were extrapolated. Analysis of collected CORALIE data ruled out the possibility that the detected radial velocity was caused by the blended spectrum of a spectroscopic binary star, supporting the possibility that the body orbiting WASP-44 was indeed a planet, designated WASP-44b
.
The Leonard Euler Telescope at La Silla Observatory
in Chile was used to follow up on the discovery circling WASP-44, searching for a point at which the planet transited, or crossed in front of, its host star. One transit was detected.
WASP-44, its recently discovered planet, the planets orbiting WASP-45 and WASP-46, and a discussion exploring the validity of the common assumption amongst scientists that closely orbiting Hot Jupiter planets have highly circular orbits unless proven otherwise, were reported in a single discovery paper that was published on May 17, 2011 by the Royal Astronomical Society
. The paper was submitted to the Monthly Notices of the Royal Astronomical Society
on May 16, 2011.
) that is located in the Cetus constellation. WASP-44 has a mass
that is 0.951 times that of the Sun. In terms of size, WASP-44 has a radius that is 0.927 times that of the Sun. WASP-44 has an effective temperature
of 5410 K, cooler than the Sun. However, its the star is metal-rich with relation to the Sun. Its measured metallicity
is [Fe/H] = 0.06, or 1.148 times that the amount of iron found in the Sun. WASP-44's chromosphere
(outermost layer) is not active. The star also does not rotate at a high velocity.
The star has an apparent magnitude
of 12.9. It cannot be seen from Earth with the naked eye
.
. The planet is a Hot Jupiter
with a mass
of 0.889 Jupiters. Its radius is 1.14 times that of Jupiter. WASP-44b orbits its host star every 2.4238039 days at a distance 0.03473 AU
, approximately 3.47% the mean distance between the Earth and Sun. With an orbital inclination of 86.02º, WASP-44b has an orbit that exists almost edge-on to its host star with respect to Earth. WASPA-44b's orbital eccentricity is fit to 0.036, indicating a mostly circular orbit.
WASP-44b
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...
in orbit. The star is slightly less massive and slightly smaller than the Sun; it is also slightly cooler, but is more metal-rich. The star was observed by 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:...
, an organization in search of planets, starting in 2009; manual follow-up observations used WASP-44's spectrum
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
and measurements of its 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...
led to the discovery of the transiting planet WASP-44b. The planet and its star were presented along with WASP-45b and WASP-46b on May 17, 2011 by a team of scientists testing the idea that Hot Jupiters tend to have circular orbits, an assumption that is made when the 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...
of such planets are not well-constrained.
Observational history
WASP-44 was observed between July and November 2009 by the WASP-South, a station of the SuperWASPSuperWASP
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:...
planet-searching program based at the South African Astronomical Observatory
South 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...
. Observations of the star revealed a periodic decrease in its brightness. WASP-South, along with the SuperWASP-North station at the Roque de los Muchachos Observatory
Roque de los Muchachos Observatory
Roque de los Muchachos Observatory is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands...
on the Canary Islands, collected 15,755 photometric
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
observations, allowing scientists to produce a more accurate light curve
Light curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time. The light is usually in a particular frequency interval or band...
. Another set of observations yielded a 6,000 point photometric data set, but the light curve was prepared late and was not considered in the discovery paper.
In 2010, a European science team investigated the star using the CORALIE spectrograph
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...
and collected seventeen spectra
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
of WASP-44. From the spectra, 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 were extrapolated. Analysis of collected CORALIE data ruled out the possibility that the detected radial velocity was caused by the blended spectrum of a spectroscopic binary star, supporting the possibility that the body orbiting WASP-44 was indeed a planet, designated WASP-44b
WASP-44b
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...
.
The Leonard Euler Telescope at 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...
in Chile was used to follow up on the discovery circling WASP-44, searching for a point at which the planet transited, or crossed in front of, its host star. One transit was detected.
WASP-44, its recently discovered planet, the planets orbiting WASP-45 and WASP-46, and a discussion exploring the validity of the common assumption amongst scientists that closely orbiting Hot Jupiter planets have highly circular orbits unless proven otherwise, were reported in a single discovery paper that was published on May 17, 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 paper was submitted to the Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society is one of the world's leading scientific journals in astronomy and astrophysics. It has been in continuous existence since 1827 and publishes peer-reviewed letters and papers reporting original research in relevant fields...
on May 16, 2011.
Characteristics
WASP-44 is a G-type star (the same class of star as the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
) that is located in the Cetus constellation. WASP-44 has a mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
that is 0.951 times that of the Sun. In terms of size, WASP-44 has a radius that is 0.927 times that of the Sun. WASP-44 has 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, cooler than the Sun. However, its the star is metal-rich with relation to the Sun. Its 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...
is [Fe/H] = 0.06, or 1.148 times that the amount of iron found in the Sun. WASP-44's chromosphere
Chromosphere
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep....
(outermost layer) is not active. The star also does not rotate at a high velocity.
The star has 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. It cannot be seen from Earth with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...
.
Planetary system
There is one known planet in the orbit of WASP-44: WASP-44bWASP-44b
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...
. The planet is a Hot Jupiter
Hot 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 Jupiters. Its radius is 1.14 times that of Jupiter. WASP-44b orbits its host star every 2.4238039 days at a distance 0.03473 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, approximately 3.47% the mean distance between the Earth and Sun. With an orbital inclination of 86.02º, WASP-44b has an orbit that exists almost edge-on to its host star with respect to Earth. WASPA-44b's orbital eccentricity is fit to 0.036, indicating a mostly circular orbit.