HD 80606 and HD 80607 are two

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s comprising a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system. They are approximately 217

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 away 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 ...

. Both stars orbit each other at an average distance of 1,200

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...

s. The binary system is listed as Σ1341 in the Struve Catalogue of Double Stars; however, this designation is not in wide use and the system is usually referred to by the HD designations of its constituent stars. An extrasolar planet has been confirmed to orbit HD 80606 in a highly elliptical orbit.

Planetary system

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 1,000 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 HD 80606 b (also Struve 1341 B b or HIP 45982 b) is an eccentric and hot Jupiter 190 light-years from the Sun in the constellation of Ursa Major. HD 80606 b was discovered orbiting the star HD 80606 in April 2001 by a team led by Michel Mayor an ...

was announced on April 4, 2001. Its orbit is misaligned with the star's rotation at 53 degrees. Additional studies using the Spitzer Space Telescope in the infrared, and the Very Large Array in the millimeter radio, have shown that the highly eccentric planet 'b' orbiting HD 80606 grazes the parent star at its closest passage to produce difficult-to-detect stellar lobing, severe 'space weather', aurorae and other non-thermal activity. At the time, its orbit was the most

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 ...

orbit of any extrasolar planet known.Since then,

HD 20782 HD 20782 is a 7th apparent magnitude, magnitude G-type main sequence star 117.5 light-years away from Earth, in the constellation of Fornax. HD 20782 is a part of a wide binary system in which the other star is designated HD 20781, and both ...

b has been found, with an eccentricity of 0.97. It has an eccentricity of 0.9336, comparable to that of

Comet Halley Halley's Comet or Comet Halley, officially designated 1P/Halley, is a List of periodic comets, 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 fr ...

in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

. 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 conclusion is reinforced by the detection of the misalignment, an expected result of the Kozai mechanism. In a simulation of a ten-million-year span, the planet "sweeps clean" most test particles within 1.75 AU of HD 80606. The 8:1 resonance hollows out another

Kirkwood gap A Kirkwood gap is a gap or dip in the distribution of the semi-major axes (or equivalently of the orbital periods) of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter. For example, there ar ...

at 1.9 AU. There cannot be any habitable planets in this system. Also, observation has ruled out planets heavier than 0.7 Jupiter mass with a period of one year or less.

References

Notes

External links

* {{Stars of Ursa Major Binary stars Planetary systems with one confirmed planet 080606 Ursa Major (constellation) G-type main-sequence stars Planetary transit variables 045982/3 Durchmusterung objects Multi-star planetary systems

Planetary system

See also

References

Notes

External links