6478 Gault, provisional designation 1988 JC1, is a Phocaea asteroid from the inner regions of the asteroid belt, approximately 3.7 kilometers (2.3 miles) in diameter. In October 2018, it was possibly impacted by an unidentified more than 500-meter-sized asteroid, causing it to become a main-belt comet with a tail. The likely S-type asteroid was discovered on 12 May 1988, by astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California. It was named for American planetary geologist Donald Gault.
|Discovered by||C. Shoemaker|
|Discovery site||Palomar Obs.|
|Discovery date||12 May 1988|
|MPC designation||(6478) Gault|
|Donald Gault |
(American planetary geologist)
|1988 JC1 · 1995 KC1|
|main-belt  · (inner)|
Phocaea  · MBC
|Orbital characteristics |
|Epoch 27 April 2019 (JD 2458600.5)|
|Uncertainty parameter 0|
|Observation arc||29.55 yr (10,792 d)|
|3.50 yr (1,278 d)|
|0° 16m 53.76s / day|
|km 3.7 (est. at 0.22)|
|0.22 (est. family-based)|
|S (est. family-based)|
Orbit and classificationEdit
Gault is a core member of the Phocaea family (701). The large asteroid family consists of nearly 2,000 known stony asteroids, and was named after its largest member, 25 Phocaea. The old family formed up to 2.2 billion years ago and has the highest inclination of all families in the inner asteroid belt. Several of its members are also Mars-crossing asteroids with high eccentricities.:23
It orbits the Sun at a distance of 1.9–2.8 AU once every 3 years and 6 months (1,278 days; semi-major axis of 2.31 AU). Its orbit has an eccentricity of 0.19 and an inclination of 23° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Palomar in May 1988.
In January 2019, it was discovered, that Gault possesses a comet tail, which had not been present in previous images. There is evidence that the asteroid became active in November 2018, and that material had been ejected from its surface, and that a collision or impact is responsible for its tail.
This minor planet was named in memory of American planetary geologist Donald Gault (1923–1999), an expert in the field of impact crater forming processes. Gault conducted field experiments and applied his insight to the interpretation of impact data from the Moon, Earth, Mars and Mercury. The official naming citation was published by the Minor Planet Center on 28 July 1999 (M.P.C. 35484).
Gault's spectral type is likely that of a common, stony S-type asteroid, according its membership to the Phocaea family. Based on a generic magnitude-to-diameter conversion, the asteroid measures approximately 3.7 kilometers in diameter, for an assumed family-specific albedo of 0.22,:23 and an absolute magnitude of 14.4. As of 2019, no rotational lightcurve of Gault has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.
- "6478 Gault (1988 JC1)". Minor Planet Center. Retrieved 10 January 2019.
- "JPL Small-Body Database Browser: 6478 Gault (1988 JC1)" (2017-11-28 last obs.). Jet Propulsion Laboratory. Retrieved 10 January 2019.
- "Asteroid 6478 Gault". Small Bodies Data Ferret. Retrieved 10 January 2019.
- "Asteroid (6478) Gault – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 May 2018.
- "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 10 January 2019.
- "Asteroid (6478) Gault has a tail!". astroblogger. 10 January 2019. Retrieved 10 January 2019.
- Carruba, V. (September 2009). "An analysis of the region of the Phocaea dynamical family". Monthly Notices of the Royal Astronomical Society. 398 (3): 1512–1526. Bibcode:2009MNRAS.398.1512C. doi:10.1111/j.1365-2966.2009.15220.x.
- Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
- Recent CBETs (CBET 4594), Minor Planet Electronic Circular, IAU–Minor Planet Center
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 10 January 2019.
- "LCDB Data for (6478) Gault – Not in Data Base". Asteroid Lightcurve Database (LCDB). Retrieved 10 January 2019.
- image of (6478) Gault showing tail, astrobin.com
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (5001)-(10000) – Minor Planet Center
- 6478 Gault at AstDyS-2, Asteroids—Dynamic Site
- 6478 Gault at the JPL Small-Body Database