![]() The comet on 31 July 2020 by ZTF | |
Discovery [1] | |
---|---|
Discovered by | LINEAR |
Discovery date | October 19, 2006 |
Designations | |
P/2006 U1, P/2011 A4 | |
Orbital characteristics [2] | |
Epoch | July 25, 2014 (2456863.5) |
Aphelion | 5.038 AU |
Perihelion | 0.502 AU |
Semi-major axis | 2.770 AU |
Eccentricity | 0.8187 |
Orbital period | 4.611 a 1684.2 d |
Inclination | 8.399° |
239.852° | |
Argument of periapsis | 64.81° |
Last perihelion | 29 June 2020 [3] |
Next perihelion | 1 February 2025 [3] |
TJupiter | 2.707 |
Earth MOID | 0.048 AU |
Comet total magnitude (M1) | 18.4 [2] |
249P/LINEAR is a periodic Jupiter-family comet with an orbital period of 4.61 years. It was discovered by LINEAR on 19 October 2006. [1] It is only active for a brief period around perihelion.
The comet was at first reported as an asteroidal object with an apparent magnitude of 17.3 by LINEAR on 19 October 2006. However it was quickly found to be cometary in appearance, with a narrow tail up to 12 arcminutes long and a coma 10 arcseconds across. [1] On 21 October the tail appeared almost disconnected from the head of the comet. A preliminary orbit suggested a short period object with an orbital period of 4.33 years. [1] The comet was recovered on 14 January 2011 by Leonid Elenin using a remote observatory of ISON, when it had an apparent magnitude of 19–19.5. [4]
249P/LINEAR has frequently passed through the fields of view of various solar observatories when near perihelion. Its most favorable apparition to date came in 2020 (perihelion June 29) when it was successfully observed by SOHO from June 16-21 (heliocentric distance, r = 0.58-0.52 AU; cometocentric distance, delta = 0.44-0.49 AU; phase angle = 163-171 deg), Parker Solar Probe on June 28 (r = 0.50 AU; delta = 0.11 AU; phase = 120 deg), and STEREO-A from July 2-16 (r = 0.50-0.62 AU; delta = 1.18-1.46 AU; phase = 53-28 deg). In addition, it was well observed by STEREO-A in April 2011 (r = 0.57-0.52 AU; delta =0.46-0.44 AU; phase = 135-166 deg) and was not detected by SOHO despite highly favorable viewing geometry in May 1997 (r = 0.79-0.73 AU; delta = 0.20-0.27 AU; phase = 168-171 deg). It was also not detected by SOHO and STEREO on several other apparitions at less favorable viewing geometries. [5]
During the 2020 apparition the comet appeared to lack a central condensation in images obtained in 20 and 21 July and with an apparent magnitude of 15 it was fainter than predicted, leading to speculation that the comet disintergrated. [6]
On 3 November 2029 the comet will approach Earth to a distance of 0.057 AU (8.5 million km) with a relative speed of 26.93 km/s. [2]
The comet has an absolute (visual) nuclear magnitude of 17.0 ± 0.4 which corresponds to a radius of 1 to 1.3 kilometers assuming an albedo of 0.04–0.07. [7] The reflection spectrum is similar to that of a B-type asteroid when the comet is near perihelion, [7] but it is weakly red when it is less active, like a typical C-type asteroid, and it appears featureless. [8]
The current orbit suggests that the orbit has been stable in the near-Earth space for about 10,000 years. It is possible that it originates from the main asteroid belt. [7] The perihelion distance appears to be slightly decreasing, meaning that it is at or near its warmest stage for the last few thousands years. [8] It is possible that the comet is dynamically linked with the Taurid complex, which was created by comet Encke. [9]
Observations of the comet during the 2006 and 2016 apparitions indicate that it is active for about 20 days around perihelion, with a dust production rate up to 145 ± 50 kg/s and a total mass loss of (2.5±0.9)×108 kg, which is low when compared with other Jupiter-family comets, indicating that it is depleted in volatiles. [7] [10] It may be near the end of its active phase and evolve to a mostly inactive body, like 3200 Phaethon. [11]
12P/Pons–Brooks is a periodic comet with an orbital period of 71 years. Comets with an orbital period of 20–200 years are referred to as Halley-type comets. It is one of the brightest known periodic comets, reaching an absolute visual magnitude of about 5 in its approach to perihelion. Comet Pons-Brooks was conclusively discovered at Marseilles Observatory in July 1812 by Jean-Louis Pons, and on its next appearance in 1883 by William Robert Brooks. There are ancient records of comets that are suspected of having been apparitions of 12P/Pons–Brooks.
3200 Phaethon, provisionally designated 1983 TB, is an active Apollo asteroid with an orbit that brings it closer to the Sun than any other named asteroid. For this reason, it was named after the Greek myth of Phaëthon, son of the sun god Helios. It is 5.8 km (3.6 mi) in diameter and is the parent body of the Geminids meteor shower of mid-December. With an observation arc of 35+ years, it has a very well determined orbit. The 2017 Earth approach distance of about 10 million km was known with an accuracy of ±700 m.
A sungrazing comet is a comet that passes extremely close to the Sun at perihelion – sometimes within a few thousand kilometres of the Sun's surface. Although small sungrazers can completely evaporate during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong evaporation and tidal forces they experience often lead to their fragmentation.
The Kreutz sungrazers are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. At the far extreme of their orbits, aphelion, Kreutz sungrazers can be a hundred times farther from the Sun than the Earth is, while their distance of closest approach can be less than twice the Sun's radius. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. These sungrazers make their way from the distant outer Solar System to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.
Comet 96P/Machholz or 96P/Machholz 1 is a short-period sungrazing comet discovered on May 12, 1986, by amateur astronomer Donald Machholz on Loma Prieta peak, in central California using 130 millimetres (5.1 in) binoculars. On June 6, 1986, 96P/Machholz passed 0.404 AU from the Earth. 96P/Machholz last came to perihelion on January 31, 2023. The comet has an estimated diameter of around 6.4 km (4.0 mi).
45P/Honda–Mrkos–Pajdušáková is a short-period comet discovered by Minoru Honda December 3, 1948. It is named after Minoru Honda, Antonín Mrkos, and Ľudmila Pajdušáková. The object revolves around the Sun on an elliptical orbit with a period of 5.25 years. The nucleus is 1.3 kilometers in diameter. On August 19 and 20, 2011, it became the fifteenth comet detected by ground radar telescope.
D/1770 L1, popularly known as Lexell's Comet after its orbit computer Anders Johan Lexell, was a comet discovered by astronomer Charles Messier in June 1770. It is notable for having passed closer to Earth than any other comet in recorded history, approaching to a distance of only 0.015 astronomical units, or six times the distance from the Earth to the Moon. The comet has not been seen since 1770 and is considered a lost comet.
354P/LINEAR, provisionally designated P/2010 A2 (LINEAR), is a small main-belt asteroid that was impacted by another asteroid sometime before 2010. It was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) at Socorro, New Mexico on 6 January 2010. The asteroid possesses a dusty, X-shaped, comet-like debris trail that has remained nearly a decade since impact. This was the first time a small-body collision had been observed; since then, minor planet 596 Scheila has also been seen to undergo a collision, in late 2010. The tail is created by millimeter-sized particles being pushed back by solar radiation pressure.
Comet C/2010 X1 (Elenin) is an Oort cloud comet discovered by Russian amateur astronomer Leonid Elenin on December 10, 2010, through remote control of the International Scientific Optical Network's robotic observatory near Mayhill in the U.S. state of New Mexico. The discovery was made using the automated asteroids discovery program CoLiTec. At the time of discovery, the comet had an apparent magnitude of 19.5, which made it about 150,000 times fainter than can be seen with the naked eye. The discoverer, Leonid Elenin, originally estimated that the comet nucleus was 3–4 km in diameter, but more recent estimates place the pre-breakup size of the comet at 2 km. Comet Elenin started disintegrating in August 2011, and as of mid-October 2011 was not visible even using large ground-based telescopes.
C/2000 W1 (Utsunomiya–Jones) is a long-period comet from the Oort cloud discovered on November 18, 2000, by Syogo Utsunomiya and Albert F. A. L. Jones. The comet reached up to apparent magnitude 5.5, but was only 27 degrees from the Sun in mid-December 2000.
479P/Elenin, with provisional designation P/2011 NO1 (Elenin), is a periodic comet with an orbital period estimated at 13.3 years.
Comet Lovejoy, formally designated C/2011 W3 (Lovejoy), is a long-period comet and Kreutz sungrazer. It was discovered in November 2011 by Australian amateur astronomer Terry Lovejoy. The comet's perihelion took it through the Sun's corona on 16 December 2011, after which it emerged intact, though greatly impacted by the event.
Comet ISON, formally known as C/2012 S1, was a sungrazing comet from the Oort cloud which was discovered on 21 September 2012 by Vitaly Nevsky and Artyom Novichonok.
209P/LINEAR is a periodic comet with an orbital period of 5.1 years. The comet has extremely low activity for its size and is probably in the process of evolving into an extinct comet.
C/2012 F6 (Lemmon) is a long-period comet discovered in Leo on 23 March 2012, by A. R. Gibbs using the 1.5-m reflector at the Mt. Lemmon Survey, located at the summit of Mount Lemmon in the Santa Catalina Mountains north of Tucson, Arizona, USA. Initially, the object was considered to be of asteroidal nature before later observations confirmed its cometary appearance. Comet Lemmon has a highly eccentric orbit, bringing it as close to 0.73 AU from the Sun at perihelion and as far as 973 AU from the Sun at aphelion. This also leads to the comet's long-period nature with an orbital period of approximately 8,000 years based on epoch 2050. The comet last reached perihelion on 24 March 2013.
Comets have been observed for over 2,000 years. During that time, several different systems have been used to assign names to each comet, and as a result many comets have more than one name.
Comet 252P/LINEAR is a periodic comet and near-Earth object discovered by the LINEAR survey on April 7, 2000. The comet is a Jupiter family comet, meaning that it passes quite close to the orbit of Jupiter.
460P/PanSTARRS (also known with the provisional designation P/2016 BA14) is a near-Earth object and periodic comet of the Jupiter family, with an orbital period of 5.25 years. In March 2016 it passed at distance of 2.2 million miles (3.5 million km, or 9 lunar distances) from Earth. It was the closest approach by a comet since 1770 and 3rd closest recorded comet to Earth. The close flyby enabled the size of the nucleus to be calculated at about 1 km (0.62 mi) in diameter, which was much bigger than expected. The comet is very dark, reflecting about 2-3 percent of the visible light, about the same as a charcoal briquette. It has a very similar orbit as numbered comet 252P/LINEAR, and may be related to it (e.g. split off of).
207P/NEAT is a periodic Jupiter-family comet with an orbital period of 7.62 years. It was discovered by Near Earth Asteroid Tracking (NEAT) on 11 March 2001.
210P/Christensen is a Jupiter family periodic comet with an orbital period of 5.7 years. It was discovered by Eric J. Christensen on 26 May 2003 in images taken by the Catalina Sky Survey and recovered in images obtained by STEREO, the first time a single-apparition comet was recovered by a spacecraft.