HD 69830
Encyclopedia
HD 69830 is an orange dwarf
star
approximately 41 light-year
s away in the constellation
of Puppis
. It has the Gould designation
285 G. Puppis, though this is infrequently used. In 2005, the Spitzer Space Telescope
discovered a debris disk
orbiting the star. The disk contains substantially more dust than the Solar System's asteroid belt
. As of 2006, it has been confirmed that three extrasolar planet
s with minimum mass
es comparable to Neptune
orbit the star, located interior to the debris disk.
star
of the spectral type K0V. The star has a mass
of about 86 percent the Sun
, 89 percent of its radius
, and 45 percent of its luminosity
. Containing less than 89 to 93 percent less iron than the Sun, recent age estimates indicated that the star is about 7 billion years old. HD 69830 is located about 41.0 light-year
s from the Sun
, lying in the northeastern part of the constellation
of Puppis
(the Poop Deck
). The star can be found east of Sirius
, southwest of Procyon
, northeast of Delta Canis Majoris
, and north of Zeta Puppis
.
In 2005, the Spitzer Space Telescope
detected a debris disk in the HD 69830 system consistent with being produced by an asteroid belt
twenty times more massive than that in our own system. The belt was originally thought to be located inside an orbit equivalent to that of Venus
in our own Solar System
, which would place it between the orbits of the second and third planets. The disk contains sufficient quantities of dust that the nights on any nearby planets would be lit up by zodiacal light
1000 times brighter than that seen on Earth
, easily outshining the Milky Way.
Further analysis of the spectrum of the dust revealed that it is composed of highly processed material, likely derived from a disrupted C-type
asteroid
of at least 30 km radius which contained many small olivine-rich (rocky) and once-wet grains which would not survive at close distances to the star. Instead, it seems more likely that the asteroid belt producing the dust is located outside the orbit of the outermost planet, around 1 AU from the star. This region contains the 2:1 and 5:2 mean motion resonances with HD 69830 d.
On May 17, 2006, a team of astronomers using the European Southern Observatory
's (ESO) HARPS spectrograph
on the 3.6-metre La Silla telescope in the Atacama desert
, Chile
, announced the discovery of three extrasolar planet
s orbiting the star. With minimum mass
es between 10 to 18 times that of the Earth
, all three planets are presumed to be similar to the planets Neptune
or Uranus
. , no planet with more than half the mass of Jupiter
had been detected within three astronomical unit
s of HD 69830.
The outermost planet discovered appears to be within the system's habitable zone
, where liquid water would remain stable (more accurate data on the primary star's luminosity will be required to know for sure where the habitable zone is). HD 69830 is the first extrasolar planetary system around a Sun-like star without any known planets comparable to Jupiter
or Saturn
in mass
.
Orange dwarf
A K-type main-sequence star , also referred to orange dwarf, are main-sequence stars of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars and yellow G-type main-sequence stars...
star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
approximately 41 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 Puppis
Puppis
Puppis is a constellation in the southern sky. Its name is the Latin word for the poop deck of a ship, and Puppis represents the deck of the ship and its deckhouses...
. It has the Gould designation
Gould designation
Gould designations for stars are similar to Flamsteed designations in the way that they number stars within a constellation in increasing order of right ascension. Each star is assigned an integer , followed by " G. " , and then the Latin genitive of the constellation it lies in...
285 G. Puppis, though this is infrequently used. In 2005, the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
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...
orbiting the star. The disk contains substantially more dust than the Solar System's asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
. As of 2006, it has been confirmed that three 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...
s with minimum mass
Minimum mass
In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets...
es comparable to Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
orbit the star, located interior to the debris disk.
Distance and visibility
HD 69830 is an orange dwarfOrange dwarf
A K-type main-sequence star , also referred to orange dwarf, are main-sequence stars of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars and yellow G-type main-sequence stars...
star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
of the spectral type K0V. The star has a mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of about 86 percent 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...
, 89 percent of its radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
, and 45 percent of its luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
. Containing less than 89 to 93 percent less iron than the Sun, recent age estimates indicated that the star is about 7 billion years old. HD 69830 is located about 41.0 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 from 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...
, lying in the northeastern part of 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 Puppis
Puppis
Puppis is a constellation in the southern sky. Its name is the Latin word for the poop deck of a ship, and Puppis represents the deck of the ship and its deckhouses...
(the Poop Deck
Poop deck
In naval architecture, a poop deck is a deck that forms the roof of a cabin built in the rear, or "aft", part of the superstructure of a ship.The name originates from the French word for stern, la poupe, from Latin puppis...
). The star can be found east of Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...
, southwest of Procyon
Procyon
Procyon is the brightest star in the constellation Canis Minor. To the naked eye, it appears to be a single star, the seventh brightest in the night sky with a visual apparent magnitude of 0.34...
, northeast of Delta Canis Majoris
Delta Canis Majoris
Delta Canis Majoris is a star in the constellation Canis Major. It has the traditional name Wezen or Wesen...
, and north of Zeta Puppis
Zeta Puppis
Zeta Puppis is a star in the constellation of Puppis. It is also known by the traditional names Naos and Suhail Hadar in Arabic....
.
Planetary system
Debris disk
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
detected a debris disk in the HD 69830 system consistent with being produced by an asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
twenty times more massive than that in our own system. The belt was originally thought to be located inside an orbit equivalent to that of Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
in our own Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
, which would place it between the orbits of the second and third planets. The disk contains sufficient quantities of dust that the nights on any nearby planets would be lit up by zodiacal light
Zodiacal light
Zodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders...
1000 times brighter than that seen on 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...
, easily outshining the Milky Way.
Further analysis of the spectrum of the dust revealed that it is composed of highly processed material, likely derived from a disrupted C-type
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
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...
of at least 30 km radius which contained many small olivine-rich (rocky) and once-wet grains which would not survive at close distances to the star. Instead, it seems more likely that the asteroid belt producing the dust is located outside the orbit of the outermost planet, around 1 AU from the star. This region contains the 2:1 and 5:2 mean motion resonances with HD 69830 d.
Planets
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
's (ESO) HARPS spectrograph
Spectrograph
A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...
on the 3.6-metre La Silla telescope in the Atacama desert
Atacama Desert
The Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, announced the discovery of three 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...
s orbiting the star. With minimum mass
Minimum mass
In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets...
es between 10 to 18 times that of 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...
, all three planets are presumed to be similar to the planets Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
or Uranus
Uranus
Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...
. , no planet with more than half the mass of 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,...
had been detected within three astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s of HD 69830.
The outermost planet discovered appears to be within the system's habitable zone
Habitable zone
In astronomy and astrobiology, a habitable zone is an umbrella term for regions that are considered favourable to life. The concept is inferred from the empirical study of conditions favourable for Life on Earth...
, where liquid water would remain stable (more accurate data on the primary star's luminosity will be required to know for sure where the habitable zone is). HD 69830 is the first extrasolar planetary system around a Sun-like star without any known planets comparable to 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,...
or Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
in mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
.
See also
- HD 169830HD 169830HD 169830 is a yellow-white dwarf star in the constellation of Sagittarius, 118.46 light years from our solar system. It is known to be orbited by two large Jupiter-like planets.- Star :...
- HD 40307
- HD 60532HD 60532HD 60532 is a white main sequence star located approximately 84 light-years away in the constellation of Puppis, taking its primary name from its Henry Draper Catalogue designation. It is calculated to be 1.44 times more massive than the Sun. The star is only 59% as old as our Sun and has...
- List of extrasolar planets
External links
- Extrasolar Planet Interactions by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona