322P/SOHO
Comet 322P/SOHO, also designated P/1999 R1, P/2003 R5, P/2007 R5, and P/2011 R4, is the first periodic comet to be discovered using the automated telescopes of the SOHO (SOlar and Heliospheric Observatory) spacecraft, and second to be given a numbered designation, after 321P/SOHO. JPL Horizons next predicts 322P to come to perihelion (closest approach to the Sun) at 2019-Aug-31 12:25 UT.
| Discovery | |
|---|---|
| Discovered by | T. Lovejoy K. Černis B. Zhou S. F. Hönig |
| Discovery date | September 4, 1999 |
| Alternative designations | P/1999 R1, P/2003 R5, P/2007 R5, P/2011 R4 |
| Orbital characteristics A | |
| Epoch | January 1, 2013 (JD 2456293.5) |
| Observation arc | 16 years |
| Number of observations | 299 |
| Aphelion | 4.978257 AU |
| Perihelion | 0.05338 AU |
| Semi-major axis | 2.5158179 AU |
| Eccentricity | 0.978783 |
| Orbital period | 3.99 yr |
| Max. orbital speed | 186 km/s (2019) |
| Min. orbital speed | 1.9 km/s (2017-Sep-01) |
| Inclination | 12.630° |
| TJupiter | 2.346 |
| Earth MOID | 0.092 AU (13,800,000 km) |
| Dimensions | ~100-200 m |
| Comet total magnitude (M1) | 19.00 ± 0.09 |
| Last perihelion | September 4, 2015[1] September 7, 2011[1] September 11, 2007[1] |
| Next perihelion | August 31, 2019 (12:25 UT)[1] |
The periodicity of this comet was predicted by Sebastian Hönig, a German graduate student and prolific asteroid discoverer, in 2006.[2] The announcement of the new periodic comet was made after the predicted return was confirmed by SOHO and observer Bo Zhou on 10 September 2007.[3] Out of approximately 1,350 SOHO-observed sungrazer comets, this is the first to be verified as a short-period comet; most sungrazers are long-period comets on near-parabolic orbits that do not repeat for thousands of years, if at all.
As it passed to within 7.9 million kilometres of the Sun, around 0.05 AU, it brightened by a factor of around a million. This is common behavior for a comet.[4]
P/2007 R5 is probably an extinct comet. Extinct comets are those that have expelled most of their volatile ice and have little left to form a tail or coma. They are theorized to be common objects amongst the celestial bodies orbiting close to the Sun. P/2007 R5 (SOHO) is probably only 100–200 meters in diameter.[4]
It was expected to return in September 2011,[4] and was recovered by B. Zhou on September 6, 2011. It has a 2.8 hour light curve period suggesting its rotation. It is uncertain whether to classify it as a dead comet or asteroid.[5]
Discovery credit goes to Terry Lovejoy (Australia, 1999), Kazimieras Černis (Lithuania, 2003), and Bo Zhou (China, 2007).
The second periodic comet discovered by SOHO is P/2003 T12 (SOHO).[6]
It was observed again in September 2019.[7]
References
- "322P/SOHO Orbit". Minor Planet Center. Retrieved April 10, 2017.
- Jaggard, Victoria (September 25, 2007). "Photo in the News: Sun Probe Spies New Periodic Comet". National Geographic News. National Geographic Society. Retrieved September 25, 2007.
- Marsden, Brian (September 18, 2007), "MPEC 2007-S16 : COMET P/1999 R1 = 2003 R5 = 2007 R5 (SOHO)", Minor Planet Electronic Circular (2007-S16)
- "SOHO's new catch: its first officially periodic comet". European Space Agency. September 25, 2007. Retrieved November 19, 2007.
- Rainer Kracht (September 7, 2011). "Recent comet discoveries 2123-2137". Yahoo Groups: SOHO Hunter. Retrieved September 11, 2011.
- Karl Battams (January 30, 2012). "The tale of a very shy comet..." Sungrazing Comets @ Navy.mil. Retrieved January 30, 2012.
- The case of the Sun-diving asteroid that thinks it's a comet Phil Plait, September 4, 2019
External links
- Orbital simulation from JPL (Java) / Ephemeris
- SOHO's first officially periodic comet
- SOHO Comets (view real-time images)
