Struve 1341
Encyclopedia
Struve 1341 is a binary star
system approximately 190 light-year
s away in the constellation
of Ursa Major
. Both stars orbit each other at an average distance of 1,200 astronomical unit
s. Both stars are more commonly referred to by their Henry Draper Catalogue
numbers: Struve 1341 A is called HD 80607, and Struve 1341 B is called HD 80606. An extrasolar planet
has been confirmed to orbit HD 80606 in a highly elliptical orbit.
Naef's team in 2001 discovered HD 80606 b
. As of June 2007, its orbit remains the most eccentric orbit of any extrasolar planet known. It has an eccentricity of 0.9336, comparable to that of Comet Halley
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 conclusion is reinforced by the possible detection of a significant misalignment between the planet's orbit and the star's equator, which would be an expected result of the Kozai mechanism.
As a result of this high eccentricity, the planet's distance from its star varies from 0.03 to 0.88 AU
. At apoapsis it would receive an insolation
similar to that of Earth
, while at periapsis the insolation would be around 800 times greater, far more than that experienced by Mercury
. This results in extreme temperature variations: observations made when the planet was eclipsed by its star revealed that the temperature rose from 800 K (500 °C / 1000 °F) to 1500 K (1200 °C / 2200 °F) in just six hours around periastron.
In a simulation of a 10 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
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.
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system approximately 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 away 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...
. Both stars orbit each other at an average distance of 1,200 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s. Both stars are more commonly referred to by their Henry Draper Catalogue
Henry Draper Catalogue
The Henry Draper Catalogue is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension , published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the...
numbers: Struve 1341 A is called HD 80607, and Struve 1341 B is called HD 80606. An extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
has been confirmed to orbit HD 80606 in a highly elliptical orbit.
Planetary system
HD 80606 b
HD 80606 b is a superjovian planet 190 light-years 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...
. As of June 2007, its orbit remains the most eccentric orbit of any extrasolar planet known. It has an eccentricity of 0.9336, comparable to that of Comet Halley
Comet Halley
Halley's Comet or Comet Halley is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime...
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 conclusion is reinforced by the possible detection of a significant misalignment between the planet's orbit and the star's equator, which would be an expected result of the Kozai mechanism.
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 apoapsis 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
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, while at periapsis the insolation would be around 800 times greater, far more than that experienced by Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
. This results in extreme temperature variations: observations made when the planet was eclipsed by its star revealed that the temperature rose from 800 K (500 °C / 1000 °F) to 1500 K (1200 °C / 2200 °F) in just six hours around periastron.
In a simulation of a 10 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
Kirkwood gap
A Kirkwood gap is a gap or dip in the distribution of main-belt asteroids with semi-major axis , as seen in the histogram below...
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.