HD 80606 and HD 80607 are two

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

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 ...

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 101 ...

s away in the constellation of

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 orbi ...

s. The binary system is listed as Σ1341 in the

Struve Catalogue of Double Stars Struve is a surname. Notable people with the surname include: Astronomers * Struve family *Jacob Struve (1755–1841) * Friedrich Georg Wilhelm von Struve (1793–1864), son of Jacob * Otto Wilhelm von Struve (1819–1905), son of Friedrich * Gust ...

; 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 An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

has been confirmed to orbit HD 80606 in a

highly elliptical orbit A highly elliptical orbit (HEO) is an elliptic orbit with high eccentricity, usually referring to one around Earth. Examples of inclined HEO orbits include Molniya orbits, named after the Molniya Soviet communication satellites which used the ...

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 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 ins ...

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 and ...

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 ...

orbit of any extrasolar planet known.Since then,

HD 20782 HD 20782 is a 7th 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 stars host plane ...

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 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 on ...

in the

Solar System The Solar System Capitalization 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 ...

. 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, Koza ...

, 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 ...

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 Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter is b ...

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