astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

, the Arcturus moving group or Arcturus stream is a

moving group In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as ...

stellar stream In astronomy, stellar kinematics is the observational study or measurement of the kinematics or motions of stars through space. Stellar kinematics encompasses the measurement of stellar velocities in the Milky Way and its satellites as well as ...

, discovered by Olin J. Eggen (1971), comprising 53 stars moving at 275,000 miles per hour, which includes the nearby bright star

Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is a red giant star in the Northern celestial hemisphere, northern constellation of Boötes, and the brightest star in the constellation. It ha ...

. It comprises many stars which share similar

proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

and so appear to be physically associated. This group of stars is not in the plane of the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

galaxy, and has been proposed as a remnant of an ancient dwarf

satellite galaxy A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and Luminosity, luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents ...

, long since disrupted and assimilated into the Milky Way. It consists of old stars deficient in heavy elements. However, Bensby and colleagues, in analysing chemical composition of F and G dwarf stars in the solar neighbourhood, found there was no difference in chemical makeup of stars from the stream, suggesting an intragalactic rather than extragalactic origin. One possibility is that the stream appeared in a manner similar to the Hercules group, which is hypothesized to have formed due to Outer Lindblad Resonance with the Galactic bar. However, it is unclear how this could produce an overdensity of stars in the thick disk. Research from the RAdial Velocity Experiment (RAVE) at the

Australian Astronomical Observatory The Australian Astronomical Observatory (AAO), formerly the Anglo-Australian Observatory, was an optical and near-infrared astronomy observatory with its headquarters in North Ryde in suburban Sydney, Australia. Originally funded jointly by the G ...

, headed by Quentin Parker, was the first to quantify the nature of the group, though astronomers had known of its existence for some time. It was first discovered in 1971. Other members include the

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The stellar atmosphere, outer atmosphere is inflated and tenuous, making the radius large and the surface t ...

Kappa Gruis κ Gruis, Latinised as Kappa Gruis, is a solitary star in the southern constellation of Grus. With an apparent magnitude of 5.37, it is visible to the naked eye as a dim, orange-hued point. The distance to this system, as determined from ...

and the M-class stars

27 Cancri 27 Cancri is a single star in the zodiac constellation of Cancer, located around 990 light-years away from the Sun. It is visible to the naked eye as a faint, red-hued star with a typical apparent visual magnitude of around +5.56. ...

Alpha Vulpeculae Alpha Vulpeculae (α Vulpeculae, abbreviated Alpha Vul, α Vul), officially named Anser , is the brightest star in the constellation of Vulpecula. It is approximately 291 light-years from Earth. It forms a wide double star, optica ...

and RT Hydrae.

References

External links

*{{cite news, url=http://www.abc.net.au/science/news/stories/s1568599.htm , title=Sucked in! Our galaxy eats neighbour, work=ABC News in Science, author=Skatssoon, Judy, date=February 14, 2006 Stellar streams Boötes Milky Way

See also

References

External links