HD 80606 b (also Struve 1341 B b or HIP 45982 b) is an

eccentric Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

and

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods (). The close proximity to their stars and high surface-atmosphere temp ...

190

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the Sun in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...

. HD 80606 b was discovered orbiting the star

HD 80606 HD 80606 and HD 80607 are two stars comprising a binary star system. They are approximately 217 light-years away in the constellation of Ursa Major. Both stars orbit each other at an average distance of 1,200 astronomical units. The binar ...

in April 2001 by a team led by

Michel Mayor Michel Gustave Édouard Mayor (; born 12 January 1942) 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 ...

and

Didier Queloz Didier Patrick Queloz (; born 23 February 1966) is a Swiss astronomer. He is the Jacksonian Professor of Natural Philosophy at the University of Cambridge, where he is also a fellow of Trinity College, Cambridge, as well as a professor at the ...

. With a mass 4 times that of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

, it is a

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...

. Because the planet transits the host star its radius can be determined using the

transit method Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty o ...

and was found to be slightly smaller than Jupiter's. Its density is slightly less than Earth's. It has an extremely eccentric orbit like a comet, with its orbit taking it very close to its star and then back out very far away from it every 111 days.

Discovery

The variable radial velocity of HD 80606 was first noticed in 1999 from observations with the 10-m Keck 1 telescope at the

W. M. Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when comp ...

in Hawaii by the G-Dwarf Planet Search, a survey of nearly 1000 nearby G dwarfs to identify extrasolar planet candidates. The star was then followed up by the

Geneva Extrasolar Planet Search The Geneva Extrasolar Planet Search is a variety of observational programs run by the Geneva Observatory at Versoix, a small town near Geneva, Switzerland. The programs are executed by M. Mayor, D. Naef, F. Pepe, D. Queloz, N.C. Santos, and S. U ...

team using the

ELODIE spectrograph ELODIE was an echelle spectrograph installed on the 1.93m reflector at the Observatoire de Haute-Provence in south-eastern France. Its optical instrumentation was developed by André Baranne from the Marseille Observatory. The purpose of the instr ...

mounted on the 1.93-m telescope at the

Haute-Provence Observatory The Haute-Provence Observatory (OHP, french: Observatoire de Haute-Provence) is an astronomical observatory in the southeast of France, about 90 km east of Avignon and 100 km north of Marseille. It was established in 1937 as a national ...

. The discovery of HD 80606 b was announced on 4 April 2001.

Physical properties

HD 80606 b has the most eccentric orbit of any known planet after

HD 20782 b HD 20782 b is an extrasolar planet located approximately 117 light-years away in the constellation of Fornax, orbiting the star HD 20782. This planet orbits in the most eccentric orbit known (as of November 2012), with a semi-major axis of ...

. Its eccentricity is 0.9336, comparable to

Halley's Comet Halley's Comet or Comet Halley, officially designated 1P/Halley, is a short-period comet visible from Earth every 75–79 years. Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and thus the o ...

. The eccentricity may be a result of the

Kozai mechanism In celestial mechanics, the Kozai mechanism is a dynamical phenomenon affecting the orbit of a binary system perturbed by a distant third body under certain conditions. It is also known as the von Zeipel-Kozai-Lidov, Lidov–Kozai mechanism, Kozai ...

, 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 The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when an object moves across the face of a star. Description The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when either an eclipsing binary's second ...

, which indicate that the planet's orbit may be significantly inclined (by 42°.) 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 An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

it would receive an

insolation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

similar to that of Earth, while at

periastron An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

the insolation would be around 800 times greater, far more than that experienced by Mercury in the 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. An observer above the cloud tops of the gas giant would see the parent star swell to 30 times the

apparent size The angular diameter, angular size, apparent diameter, or apparent size is an angular distance describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is ...

of the Sun in our own sky. The transit was detected using a

Celestron Celestron is an American company based in Torrance, California, United States, that manufactures telescopes and distributes telescopes, binoculars, spotting scopes, microscopes, and accessories manufactured by its parent company, the Synta Technolo ...

35-cm

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 The Am ...

at the

UCL Observatory UCL Observatory (called the University of London Observatory until 2015) at Mill Hill in London is an astronomical teaching observatory. It is part of the Department of Physics and Astronomy at University College London. History The Observator ...

. Prior to the large data release of the

Kepler Mission The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

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 transit of 14 January 2010 was partially observed by MOST; but there were equipment failures over part of this time, and the 8 January secondary transit was entirely lost. The midpoint of the next transit was 1 February 2013 11:37 UT.HD 80606 Transit Times – Variable Star and Exoplanets
/ref>

Weather

The planet has wild variations in its weather as it orbits its parent star. Computer models predict the planet heats up in just a matter of hours, triggering "

shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a med ...

storms" that ripple out from the point facing its star, with winds that move at around .

Notes

References

External links

Heating Up on a Distant Planet (ScienceFriday)
{{Sky, 09, 22, 37.5679, +, 50, 36, 13.397, 190 Ursa Major (constellation) Giant planets Exoplanets discovered in 2001 Exoplanets detected by radial velocity Transiting exoplanets