WASP-43
Encyclopedia
WASP-43 is a K-type star in the Sextans
constellation. It is almost the same size as the Sun, but approximately half the mass. WASP-43 has one known planet in orbit, a Hot Jupiter
called WASP-43b
. At the time of publishing of WASP-43b's discovery on April 15, 2011, the planet was the most closely orbiting Hot Jupiter discovered. The small orbit of WASP-43b is thought to be caused by WASP-43's unusually low mass. WASP-43 was first observed between January and May 2009 by the SuperWASP
project, and was found to be cooler and slightly richer in metals than the Sun. WASP-43 has also been found to be an active star that rotates at a high velocity.
project between January and May 2009. It was determined from the collected data that WASP-43 could potentially host a planet that transited, or crossed in front of, its host star as seen from Earth. Later observations by both the WASP-South and SuperWASP-North sections of SuperWASP between January and May 2010 yielded a total of 13,768 data points.
Scientists interpreted that a 0.81-day orbit of a possible planet from the data, and followed up with observations using the CORALIE spectrograph
on the Leonhard Euler Telescope
at Chile's La Silla Observatory
. CORALIE provided radial velocity
measurements that indicated that WASP-43 was being transited by a planet that was 1.8 times Jupiter's mass, now dubbed WASP-43b
. Another follow-up using the TRAPPIST
telescope further defined the light curve
of the body transiting WASP-43.
WASP-43b's discovery was reported on April 15, 2011 in the journal Astronomy and Astrophysics
.
that is 0.58 times that of the Sun, and a radius that is 0.93 times that of the Sun. In other words, WASP-43 is far less massive than the Sun, but is approximately the same size. With an effective temperature
of 4400 K, WASP-43 is cooler than the Sun. It also has slightly lower quantities of iron than the Sun, with a measured metallicity
of [Fe/H] = -0.05 (89% of that measured in the Sun). However, in general, the star has a slightly larger quantity of metals than the Sun. A notable exception is lithium
, which is not present in WASP-43's spectrum. However, the star's spectrum also indicates that WASP-43 is an active star. WASP-43 has been found to rotate quickly, although the exact mechanism that causes such speed in this rotation is uncertain, it may be possible that this is caused by tidal interactions between WASP-43 and its planet.
With an apparent magnitude
of 12.4, WASP-43 cannot be seen with the unaided eye. The star is located approximately 80 parsecs (260 light years) away from Earth.
with a mass that is 1.78 times the mass of Jupiter
and a radius that is 0.93 times Jupiter's radius. WASP-43b orbits its host star every 0.813475 days (19.5234 hours) at a distance of 0.0142 AU
, the closest orbit yet found at the time of WASP-43b's discovery. WASP-43's unusually low mass accounts for WASP-43b's small orbit. Because planets with orbits around stars like WASP-43 are not usually observed, models either suggest that planets like WASP-43b are either uncommon or have short lifetimes caused by a decay in their orbits.
Sextans
Sextans is a minor equatorial constellation which was introduced in 1687 by Johannes Hevelius. Its name is Latin for the astronomical sextant, an instrument that Hevelius made frequent use of in his observations.-Notable features:...
constellation. It is almost the same size as the Sun, but approximately half the mass. WASP-43 has one known planet in orbit, a Hot Jupiter
Hot Jupiter
Hot Jupiters are a class of extrasolar planet whose mass is close to or exceeds that of Jupiter...
called WASP-43b
WASP-43b
WASP-43b is a transiting planet in orbit around the young, active, and low-mass star WASP-43 in the constellation Sextans. The planet is a Hot Jupiter with a mass almost twice that of Jupiter, but a radius that is slightly less than Jupiter's...
. At the time of publishing of WASP-43b's discovery on April 15, 2011, the planet was the most closely orbiting Hot Jupiter discovered. The small orbit of WASP-43b is thought to be caused by WASP-43's unusually low mass. WASP-43 was first observed between January and May 2009 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:...
project, and was found to be cooler and slightly richer in metals than the Sun. WASP-43 has also been found to be an active star that rotates at a high velocity.
Observational history
WASP-43 was first observed by the WASP-South part of the planet-searching 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:...
project between January and May 2009. It was determined from the collected data that WASP-43 could potentially host a planet that transited, or crossed in front of, its host star as seen from Earth. Later observations by both the WASP-South and SuperWASP-North sections of SuperWASP between January and May 2010 yielded a total of 13,768 data points.
Scientists interpreted that a 0.81-day orbit of a possible planet from the data, and followed up with observations 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...
on the 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...
. CORALIE provided 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 that indicated that WASP-43 was being transited by a planet that was 1.8 times Jupiter's mass, now dubbed WASP-43b
WASP-43b
WASP-43b is a transiting planet in orbit around the young, active, and low-mass star WASP-43 in the constellation Sextans. The planet is a Hot Jupiter with a mass almost twice that of Jupiter, but a radius that is slightly less than Jupiter's...
. Another follow-up using the TRAPPIST
TRAPPIST
TRAPPIST is Belgian robotic telescope in Chile which came online in 2010, and is an acronym for TRAnsiting Planets and PlanetesImals Small Telescope, so named in homage to Trappist beer produced in the Belgian region. Situated high in the Chilean mountains at La Silla Observatory, it is actually...
telescope further defined the 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...
of the body transiting WASP-43.
WASP-43b's discovery was reported on April 15, 2011 in the journal Astronomy and Astrophysics
Astronomy and Astrophysics
* Astronomy and Astrophysics has a 2010 impact factor of 4.410.-See also:*The Astronomy and Astrophysics Review*Advanced Satellite for Cosmology and Astrophysics*Astronomy & Geophysics*Astronomical Journal*Astrophysical Journal...
.
Characteristics
WASP-43 is a K-type star with a massSolar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
that is 0.58 times that of the Sun, and a radius that is 0.93 times that of the Sun. In other words, WASP-43 is far less massive than the Sun, but is approximately the same size. 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 4400 K, WASP-43 is cooler than the Sun. It also has slightly lower quantities of iron than the Sun, 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] = -0.05 (89% of that measured in the Sun). However, in general, the star has a slightly larger quantity of metals than the Sun. A notable exception is lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
, which is not present in WASP-43's spectrum. However, the star's spectrum also indicates that WASP-43 is an active star. WASP-43 has been found to rotate quickly, although the exact mechanism that causes such speed in this rotation is uncertain, it may be possible that this is caused by tidal interactions between WASP-43 and its planet.
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 12.4, WASP-43 cannot be seen with the unaided eye. The star is located approximately 80 parsecs (260 light years) away from Earth.
Planetary system
WASP-43b 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 that is 1.78 times the mass of Jupiter
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....
and a radius that is 0.93 times Jupiter's radius. WASP-43b orbits its host star every 0.813475 days (19.5234 hours) at a distance of 0.0142 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, the closest orbit yet found at the time of WASP-43b's discovery. WASP-43's unusually low mass accounts for WASP-43b's small orbit. Because planets with orbits around stars like WASP-43 are not usually observed, models either suggest that planets like WASP-43b are either uncommon or have short lifetimes caused by a decay in their orbits.