Gould Belt
Encyclopedia
The Gould Belt is a partial ring of star
s in the Milky Way
galaxy, about 3000 light years
across, tilted toward the galactic plane
by about 16 to 20 degrees. It contains many spectral class O- and B-type stars, and may represent the local spiral arm to which the Sun
belongs—currently the Sun is about 325 light years from the arm's center. The belt is thought to be from 30 to 50 million years old, and of unknown origin. It is named for Benjamin Gould, who identified it in 1879.
The belt contains bright stars in many constellations including (in order going more or less eastward) Cepheus
, Lacerta
, Perseus
, Orion
, Canis Major
, Puppis
, Vela
, Carina
, Crux (the Southern Cross), Centaurus
, Lupus
, and Scorpius
(including the Scorpius-Centaurus Association
). The Milky Way also passes through most of these constellations, but a bit south-east of Lupus.
A late 2000s theory is that the Gould Belt formed about 30 million years ago when a blob of dark matter
collided with the molecular cloud
in our region. There is also evidence for similar Gould belts in other galaxies.
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...
s in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy, about 3000 light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
across, tilted toward the galactic plane
Galactic plane
The galactic plane is the plane in which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles...
by about 16 to 20 degrees. It contains many spectral class O- and B-type stars, and may represent the local spiral arm to which 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...
belongs—currently the Sun is about 325 light years from the arm's center. The belt is thought to be from 30 to 50 million years old, and of unknown origin. It is named for Benjamin Gould, who identified it in 1879.
The belt contains bright stars in many constellations including (in order going more or less eastward) Cepheus
Cepheus (constellation)
Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations.-Stars:...
, Lacerta
Lacerta
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was created in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" shape similar to that of Cassiopeia, and it is thus...
, Perseus
Perseus (constellation)
Perseus is a constellation in the northern sky, named after the Greek hero Perseus. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations defined by the International Astronomical Union...
, Orion
Orion (constellation)
Orion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky...
, Canis Major
Canis Major
Canis Major is one of the 88 modern constellations, and was included in the 2nd-century astronomer Ptolemy's 48 constellations. Its name is Latin for 'greater dog', and is commonly represented as one of the dogs following Orion the hunter...
, 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...
, Vela
Vela (constellation)
Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis.-Stars:...
, Carina
Carina (constellation)
Carina is a constellation in the southern sky. Its name is Latin for the keel of a ship, and it was formerly part of the larger constellation of Argo Navis until that constellation was divided in three.-Stars:...
, Crux (the Southern Cross), Centaurus
Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...
, Lupus
Lupus (constellation)
Lupus is a constellation in the southern sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations...
, and Scorpius
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
(including the Scorpius-Centaurus Association
Scorpius-Centaurus Association
The Scorpius-Centaurus Association is the nearestOB Association to the Sun. This stellar association is composed of three subgroups The Scorpius-Centaurus Association (sometimes called Sco-Cen or Sco OB2) is the nearestOB Association to the Sun. This stellar association is composed of three...
). The Milky Way also passes through most of these constellations, but a bit south-east of Lupus.
A late 2000s theory is that the Gould Belt formed about 30 million years ago when a blob of dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
collided with the molecular cloud
Molecular cloud
A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen ....
in our region. There is also evidence for similar Gould belts in other galaxies.
External links
See also
- Gould Belt SurveyGould Belt SurveyThe Gould Belt Survey is an astronomical research project led by the Harvard-Smithsonian Center for Astrophysics, with the participation of several other institutions....
- Local BubbleLocal BubbleThe Local Bubble is a cavity in the interstellar medium of the Orion Arm of the Milky Way. It is at least 300 light years across and has a neutral hydrogen density of about 0.05 atoms per cubic centimetre, or approximately one tenth of the average for the ISM in the Milky Way , and half that for...
- Local Interstellar CloudLocal Interstellar CloudThe Local Interstellar Cloud is the interstellar cloud roughly 30 light years across through which the Earth's solar system is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain...
- Orion ArmOrion ArmThe Orion–Cygnus Arm is a minor spiral arm of the Milky Way galaxy some 3,500 light years across and approximately 10,000 light years in length. The Solar System is within the Orion–Cygnus Arm...
- Perseus ArmPerseus ArmThe Perseus Arm is one of two major spiral arms of the Milky Way galaxy. The second major arm is called Scutum–Centaurus Arm. Perseus Arm begins from the distal end of the long Milky Way....
- The Magnificent Seven (neutron stars)The Magnificent Seven (neutron stars)The Magnificent Seven is the informal name of a group of isolated young cooling neutron stars near to Earth . These objects are also known under the names XDINS and XTINS .-History:The first to fit this classification was RX J1856.5-3754, which was discovered by Walter et al...