P/2019 LD2 (ATLAS) explained

Minorplanet:yes
(ATLAS)
Background:
  1. FFE0C2
Discovery Ref: 
Discovered:10 June 2019 (first observed)
Mp Category:Jupiter-family comet
periodic 
centaur 
Orbit Ref: 
Epoch:27 July 2019 (JD 2458691.5)
Uncertainty:4
Observation Arc:2.00 yr (729 d)
Earliest Precovery Date:21 May 2018
Perihelion:4.5784 AU
Semimajor:5.3279 AU
Eccentricity:0.14068
Period:12.3 yr
Mean Motion: / day
Inclination:11.517°
Asc Node:180.217°
Arg Peri:122.688°
Jupiter Moid:0.0334843 AU
Tisserand:2.940
Magnitude:19.0
Abs Magnitude:
12.1

(ATLAS) is a Jupiter-family comet discovered by the Asteroid Terrestrial-impact Last Alert System on 10 June 2019.[1] [2] It was initially reported as the first known Jupiter trojan asteroid to display cometary activity, but its classification as a Jupiter trojan was retracted after closer examination and a longer observation arc revealed its orbit to be unstable like a typical Jupiter family comet and implied that its position near the trojans is temporary.

Discovery

was discovered in images by the Asteroid Terrestrial-impact Last Alert System (ATLAS) at the Mauna Loa Observatory taken on 10 June 2019. Upon discovery, astronomers Alan Fitzsimmons and David Young at Queen's University Belfast suspected a faint coma around . Follow-up observations by the Las Cumbres Observatory in 11 and 13 June 2019 confirmed the cometary appearance of, which now had a more apparent coma and tail. Later observations by the ATLAS-MLO in April 2020 showed that still retained its cometary appearance, suggesting that it has been continuously active for almost a year.

The discovery of 's cometary activity was announced in a press release by the University of Hawaiʻi Institute for Astronomy on 20 May 2020, purporting it as the first known active Jupiter trojan, as it was discovered near Jupiter's Lagrangian point where the Greek camp trojans reside. However, upon closer examination of 's orbital dynamics by amateur astronomer Sam Deen, was found to be a Jupiter-family comet with a chaotic orbit instead of a Jupiter trojan. Subsequently, the comet was reclassified and was given the periodic comet designation (ATLAS) by the Minor Planet Center on 22 May 2020.

Orbit and classification

orbits the Sun at a mean distance of 5.29 AU once every 12.18 years. Its orbit has an eccentricity of 0.135 and an inclination of 11.6 degrees with respect to the ecliptic. The body's observation arc begins with a precovery, published by the Pan-STARRS 1 survey and taken at Haleakala Observatory on 21 May 2018, or 11 months prior to its official discovery observation by the ALTAS-MLO survey.

is a Jupiter-family comet with a Tisserand parameter of 2.94, typical for other Jupiter-family comets. The comet's nominal orbit suggests that it is not in a stable 1:1 resonance with Jupiter as it has made a close approach to the planet on 17 February 2017, at a distance of 0.092AU, and will make a similarly close approach in 2028. Unlike the Jupiter trojans, is 21 degrees ahead of Jupiter, and will continue drifting 30 degrees ahead before returning to Jupiter and making close approaches. is now following what looks like a short arc of a quasi-satellite cycle with respect to Jupiter that started in 2017 and will end in 2028.[3]

[4] On 2063 January 23, it will have a very close encounter with Jupiter at 0.016 AU; orbital predictions after this flyby are rather uncertain.[4]

Physical characteristics

Based on a generic magnitude-to-diameter conversion, measures approximately 14 kilometers in diameter, for an assumed albedo of 0.12 as the median for small Jupiter trojans, and an absolute magnitude of 12.2., no rotational light curve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown. The visible spectrum does not exhibit any evidence of CN, C2, or C3 emission.

During the approach to perihelion in 2020, the comet shed large-grained (0.1 mm typical) dust grains rich with water ice.

See also

External links

Notes and References

  1. News: Andrews . Robin George . A 'Front-Row Seat' to the Birth of a Comet - Astronomers are watching an object transform into a hyperactive comet that will head toward the inner solar system in the coming decades. . 3 December 2020 . . 3 December 2020 .
  2. Steckloff, J.K. . et al. . P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family . 26 November 2020 . . 904 . 2 . L20 . 10.3847/2041-8213/abc888 . 2008.02943 . 221083420 . free . 2020ApJ...904L..20S .
  3. Bryce T. . Bolin . Yanga R. . Fernandez . Carey M. . Lisse . Timothy R. . Holt . Zhong-Yi . Lin . Josiah N. . Purudm . Kunal P. . Deshmukh . James M. . Bauer . Eric C. . Bellm . March 2021 . Initial Characterization of Active Transitioning Centaur, P/2019 LD2 (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy . The Astronomical Journal . 161 . 116 . 116 . 10.3847/1538-3881/abd94b . 2011.03782 . 2021AJ....161..116B. 234356588 . free .
  4. Licandro . Javier. de Leon . Julia. Moreno . Fernando. de la Fuente Marcos . Carlos. de la Fuente Marcos . Raúl. Cabrera-Lavers . Antonio. Lara . Luisa. de Souza-Feliciano . Ana Carolina. De Prá . Mario. Pinilla-Alonso . Noemi. Geier . Stefan. Activity of the Jupiter co-orbital comet P/2019 LD2 (ATLAS) observed with OSIRIS at the 10.4 m GTC. Astronomy and Astrophysics . 650 . A79 (10 pp). 8 June 2021. 10.1051/0004-6361/202038842. 2021A&A...650A..79L. 2103.14613 . 232380303.