118401 LINEAR, provisional designation , is an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

and

main-belt comet Active asteroids are small Solar System bodies that have asteroid-like orbits but show comet-like visual characteristics. That is, they show comae, tails, or other visual evidence of mass-loss (like a comet), but their orbit remains within Jup ...

(176P/LINEAR)(older 2010 site)
that was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) 1-metre telescopes in

Socorro, New Mexico Socorro (, '' sə-KOR-oh'') is a city in Socorro County in the U.S. state of New Mexico. It is in the Rio Grande Valley at an elevation of . In 2010 the population was 9,051. It is the county seat of Socorro County. Socorro is located south of A ...

on September 7, 1999. (118401) LINEAR was discovered to be cometary on November 26, 2005, by

Henry H. Hsieh Henry may refer to: People *Henry (given name) *Henry (surname) * Henry Lau, Canadian singer and musician who performs under the mononym Henry Royalty * Portuguese royalty ** King-Cardinal Henry, King of Portugal ** Henry, Count of Portugal ...

and

David C. Jewitt David Clifford Jewitt (born 1958) is a British-American astronomer who studies the Solar System, especially its minor bodies. He is based at the University of California, Los Angeles, where he is a Member of the Institute for Geophysics and Pl ...

as part of the Hawaii Trails project using the Gemini North 8-m telescope on

Mauna Kea Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak is ...

and was confirmed by the University of Hawaii's 2.2-m (88-in) telescope on December 24–27, 2005, and Gemini on December 29, 2005. Observations using the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

have resulted in an estimate of 4.0±0.4 km for the diameter of (118401) LINEAR. The main-belt comets are unique in that they have flat (within the plane of the planets' orbits), approximately circular (small eccentricity),

-like

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

s, and not the elongated, often tilted orbits characteristic of all other comets. Because (118401) LINEAR can generate a

coma A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal wake-sleep cycle and does not initiate voluntary actions. Coma patients exhi ...

(produced by vapour boiled off the comet), it must be an icy asteroid. When a typical comet approaches the Sun, its

ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...

heats up and sublimates (changes directly from ice to

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

), venting gas and

dust Dust is made of fine particles of solid matter. On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution. Dust in homes ...

into

space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...

, creating a tail and giving the object a fuzzy appearance. Far from the Sun, sublimation stops, and the remaining ice stays frozen until the comet's next pass close to the Sun. In contrast, objects in the asteroid belt have essentially circular orbits and are expected to be mostly baked dry of ice by their confinement to the inner Solar System (see extinct comet). It is suggested that these main-belt asteroid-comets are evidence of a recent impact exposing an icy interior to solar radiation. It is estimated short-period comets remain active for about 10,000 years before having most of their ice sublimated away and going dormant. Eight other objects are classified as both periodic comets and numbered asteroids:

2060 Chiron 2060 Chiron is a small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orb ...

(95P/Chiron),

4015 Wilson–Harrington 4015 Wilson–Harrington is an active asteroid known both as comet 107P/Wilson–Harrington and as asteroid 4015 Wilson–Harrington. It will pass from Earth on 20 July 2022 and then pass perihelion (closest approach to the Sun) on 24 August 20 ...

(107P/Wilson–Harrington),

7968 Elst–Pizarro Comet Elst–Pizarro is a body that displays characteristics of both asteroids and comets, and is the prototype of active asteroids. Its orbit keeps it within the asteroid belt, yet it displayed a dust tail like a comet while near perihelion in 19 ...

(133P/Elst–Pizarro),

60558 Echeclus 60558 Echeclus is a centaur, approximately in diameter, located in the outer Solar System. It was discovered by Spacewatch in 2000 and initially classified as a minor planet with provisional designation (also written 2000 EC98). Research in 20 ...

(174P/Echeclus), (282P/2003 BM₈₀), (288P/2006 VW₁₃₉), (362P/2008 GO₉₈), and (433P/2005 QN₁₇₃).M.P.C. 133823
/ref> As a dual-status object,

astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. Histor ...

observations of 118401 LINEAR should be reported under the

minor planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...

. 118401 LINEAR last came to perihelion on 2017 March 12.

References

External links

118401
on November 13, 2011
LINEAR home page

Seiichi Yoshida's comet list

* * {{DEFAULTSORT:Linear, 176P 118401 176P 0176 118401 118401 Named minor planets 19990907