HD 80606 b
Encyclopedia
HD 80606 b is a superjovian planet (Eccentric Jupiter
) 190 light-year
s distant in the constellation
of Ursa Major
. The planet was discovered orbiting the star Struve 1341 B
in April 2001 by a team led by Michel Mayor
and Didier Queloz
. Based on its mass, at 4 times that of Jupiter
, it is a gas giant
. Since the planet transits its star, its radius is determined to be slightly smaller than Jupiter's. Its density is slightly less than Earth's.
HD 80606 b has the most eccentric orbit of any extrasolar planet known. It has an eccentricity of 0.9336, comparable to that of Comet Halley's Comet
in our solar system. The eccentricity may be a result of the Kozai mechanism
, which would occur if the planet's orbit is significantly inclined to that of the binary stars. This interpretation is supported by measurements of the Rossiter-McLaughlin effect
, which indicate that the planet's orbit may be significantly inclined to the rotational axis of the star, a configuration which would be expected if the Kozai mechanism were responsible for the orbit.
As a result of this high eccentricity, the planet's distance from its star varies from 0.03 to 0.88 AU
. At apastron it would receive an insolation
similar to that of Earth, while at periastron the insolation would be around 800 times greater, far more than that experienced by Mercury in our solar system. In 2009, the eclipse of HD 80606 b by its parent star was detected, allowing measurements of the planet's temperature to be made as the planet passed through periastron. These measurements indicated that the temperature rose from around 800 K (500 °C / 1000 °F) to 1500 K (1200 °C / 2200 °F) in just 6 hours.
A hypothetical observer above the cloud tops of the gas giant would see the parent star swell to 30 times the apparent size of the Sun in our own sky.
The transit was detected using a Celestron
35-cm Schmidt-Cassegrain telescope
. Prior to the large data release of the Kepler Mission
in February 2011, HD 80606 b has the longest orbital period of any known transiting planet. It takes 12.1 hours to transit its star. The midpoint of the next transit is August 19, 2010 1:00 UT
.
, at 3 miles per second.
Eccentric Jupiter
An eccentric Jupiter is a Jovian planet that orbits its star in an eccentric orbit. Eccentric Jupiters may disqualify a planetary system from having Earth-like planets in it because a massive gas giant with an eccentric orbit may remove all Earth mass planets from the habitable zone.To date, it...
) 190 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s distant in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Ursa Major
Ursa Major
Ursa Major , also known as the Great Bear, is a constellation visible throughout the year in most of the northern hemisphere. It can best be seen in April...
. The planet was discovered orbiting the star Struve 1341 B
Struve 1341
Struve 1341 is a binary star system approximately 190 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. Both stars are more commonly referred to by their Henry Draper Catalogue numbers: Struve 1341 A is called HD...
in April 2001 by a team led by Michel Mayor
Michel Mayor
Dr. Michel G. E. Mayor is a Swiss astrophysicist and professor emeritus at the University of Geneva's Department of Astronomy. He formally retired in 2007, but remains active as a researcher at the Observatory of Geneva...
and Didier Queloz
Didier Queloz
Didier Queloz is a Geneva-based astronomer with a prolific record in finding extrasolar planets. He is understudy to Michel Mayor.Didier Queloz was a Ph.D...
. Based on its mass, at 4 times that of Jupiter
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,...
, it is a gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
. Since the planet transits its star, its radius is determined to be slightly smaller than Jupiter's. Its density is slightly less than Earth's.
Physical properties
Halley
-People:* Antoine Halley , French poet*Edmond Halley , English Astronomer Royal* Robert Halley , English Congregationalist minister and abolitionist* Paul-Louis Halley , French businessman...
in our solar system. The eccentricity may be a result of the Kozai mechanism
Kozai mechanism
In celestial mechanics, the Kozai mechanism, or the Lidov-Kozai mechanism, causes a periodic exchange between the inclination and eccentricity of an orbit...
, which would occur if the planet's orbit is significantly inclined to that of the binary stars. This interpretation is supported by measurements of the Rossiter-McLaughlin effect
Rossiter-McLaughlin effect
The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's secondary star or an extrasolar planet is seen to transit across the face of the primary or parent star. As the main star rotates on its axis, one quadrant of its photosphere will be seen to be...
, which indicate that the planet's orbit may be significantly inclined to the rotational axis of the star, a configuration which would be expected if the Kozai mechanism were responsible for the orbit.
As a result of this high eccentricity, the planet's distance from its star varies from 0.03 to 0.88 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
. At apastron it would receive an insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
similar to that of Earth, while at periastron the insolation would be around 800 times greater, far more than that experienced by Mercury in our solar system. In 2009, the eclipse of HD 80606 b by its parent star was detected, allowing measurements of the planet's temperature to be made as the planet passed through periastron. These measurements indicated that the temperature rose from around 800 K (500 °C / 1000 °F) to 1500 K (1200 °C / 2200 °F) in just 6 hours.
A hypothetical observer above the cloud tops of the gas giant would see the parent star swell to 30 times the apparent size of the Sun in our own sky.
The transit was detected using a Celestron
Celestron
Celestron is a company that manufactures and imports telescopes, binoculars, spotting scopes, microscopes, and accessories for their products.-Origins and History:...
35-cm Schmidt-Cassegrain telescope
Schmidt-Cassegrain telescope
The Schmidt–Cassegrain is a catadioptric telescope that combines a cassegrain reflector's optical path with a Schmidt corrector plate to make a compact astronomical instrument that uses simple spherical surfaces.-Invention and design:...
. Prior to the large data release of the Kepler Mission
Kepler Mission
The Kepler spacecraft is an American space observatory, the space-based portion of NASA's Kepler Mission to discover Earth-like planets orbiting other stars. The spacecraft is named in honor of the 17th-century German astronomer Johannes Kepler...
in February 2011, HD 80606 b has the longest orbital period of any known transiting planet. It takes 12.1 hours to transit its star. The midpoint of the next transit is August 19, 2010 1:00 UT
Universal Time
Universal Time is a time scale based on the rotation of the Earth. It is a modern continuation of Greenwich Mean Time , i.e., the mean solar time on the Prime Meridian at Greenwich, and GMT is sometimes used loosely as a synonym for UTC...
.
Weather
The planet has wild variations in its weather as it orbits its parent star. Computer models predict the planet heats up 555 C-change in just a matter of hours triggering "shock wave storms" with winds that move faster than the speed of soundSpeed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
, at 3 miles per second.