HD 98800
Encyclopedia
HD 98800, also catalogued as TV Crateris (TV Crt), is a quadruple star system approximately 150 light-year
s away in the constellation
of Crater
(the Cup). The system is located within the TW Hydrae association
. The system consists of "HD 98800 A" and "HD 98800 B" each of which contains two stars.
In 2007, a debris disk
was discovered orbiting "HD 98800 B" consisting of two rings which indicates there may be an extrasolar planet
orbiting within a distance of 1.5 to 2 astronomical units.
s that are located within the TW Hydrae association
. Within the system, there are two separate systems of binary stars. Each system (separately catalogued as "HD 98800 A" and "HD 98800B") consists of two stars. Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical unit
s (somewhat more than the average distance between the Sun
and Pluto
). Not much is known about each individual star, except that they are basically Solar twin stars.
Astronomers using the Spitzer Space Telescope
's infrared detector discovered a debris disk
around the "HD 98800B" binary system. The disk consists of two separate belts. The inner ring extends from a distance of 1.5 to 2 astronomical unit
s from the barycenter
of the central binary. The outer ring begins at approximately 5.9 astronomical units from the central binary, and extends out an undetermined distance. The gap between the two rings is ~3 astronomical units. The inner ring is thin, while the inner portion of the outer ring is dense.
Project leader, Dr. Elise Furlan, concludes that the dust generated from the collision of rocky objects in the outer belt should eventually migrate toward the inner disk. But because the system is a double binary system, the dust particles do not evenly fill out the inner disk as expected.
Astronomers believe that planets form like snowballs over millions of years, as small dust grains clump together to form larger bodies. Some of these cosmic rocks then smash together to form Terrestrial planet
s (such as the Earth
), or the cores of Jovian planets (such as Jupiter
). Large rocks that don't form planets often become asteroid
s and comet
s. As these rocky structures violently collide, bits of dust are released into space.
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 Crater
Crater (constellation)
Crater is a constellation. Its name is Latin for cup, and in Greek mythology it is identified with the cup of the god Apollo. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations...
(the Cup). The system is located within the TW Hydrae association
TW Hydrae association
The TW Hydrae association is a group of approximately thirty very young stars located 50 parsecs from Earth that share a common motion and appear to all be roughly the same age, 5-10 million years old...
. The system consists of "HD 98800 A" and "HD 98800 B" each of which contains two stars.
In 2007, a debris disk
Debris disk
A debris disk is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a...
was discovered orbiting "HD 98800 B" consisting of two rings which indicates there may be 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...
orbiting within a distance of 1.5 to 2 astronomical units.
Stellar system
The system consists of four T Tauri starT Tauri star
T Tauri stars are a class of variable stars named after their prototype – T Tauri. They are found near molecular clouds and identified by their optical variability and strong chromospheric lines.-Characteristics:...
s that are located within the TW Hydrae association
TW Hydrae association
The TW Hydrae association is a group of approximately thirty very young stars located 50 parsecs from Earth that share a common motion and appear to all be roughly the same age, 5-10 million years old...
. Within the system, there are two separate systems of binary stars. Each system (separately catalogued as "HD 98800 A" and "HD 98800B") consists of two stars. Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s (somewhat more than the average distance between the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
). Not much is known about each individual star, except that they are basically Solar twin stars.
Debris disk
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
's infrared detector discovered a debris disk
Debris disk
A debris disk is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both evolved and young stars, as well as at least one debris disk in orbit around a...
around the "HD 98800B" binary system. The disk consists of two separate belts. The inner ring extends from a distance of 1.5 to 2 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s from the barycenter
Barycentric coordinates (astronomy)
In astronomy, barycentric coordinates are non-rotating coordinates with origin at the center of mass of two or more bodies.The barycenter is the point between two objects where they balance each other. For example, it is the center of mass where two or more celestial bodies orbit each other...
of the central binary. The outer ring begins at approximately 5.9 astronomical units from the central binary, and extends out an undetermined distance. The gap between the two rings is ~3 astronomical units. The inner ring is thin, while the inner portion of the outer ring is dense.
Project leader, Dr. Elise Furlan, concludes that the dust generated from the collision of rocky objects in the outer belt should eventually migrate toward the inner disk. But because the system is a double binary system, the dust particles do not evenly fill out the inner disk as expected.
Possible planets
Debris disks are thought to constitute a phase in planetary formation. Because of the gap within the debris disk, the possibility of a planet within the system becomes even more likely. The detected gap could be caused by a unique gravitational relationship between the disk and a possible planet already begun to form, carving out a clear space in the disk. However, the gap could also be gravitational resonance effects of the four stars.Astronomers believe that planets form like snowballs over millions of years, as small dust grains clump together to form larger bodies. Some of these cosmic rocks then smash together to form Terrestrial planet
Terrestrial planet
A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun...
s (such as the 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...
), or the cores of Jovian planets (such as 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,...
). Large rocks that don't form planets often become asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
s and comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s. As these rocky structures violently collide, bits of dust are released into space.