060520 MK

Sungrazing Comets : Sungrazing Comets Matthew Knight University of Maryland (or How you can find comets without being a professional astronomer)


Halley’s Comet : Halley’s Comet 1910 1986


Hale-Bopp (1995) : Hale-Bopp (1995) Hyakutake (1996)


Kohoutek (1973) : Kohoutek (1973)


Tempel 1 (2005) : Tempel 1 (2005) SW3 (2006)


What is a sungrazing comet? : What is a sungrazing comet? Comets that “graze” the Sun’s surface Orbits pass within a few solar radii of the Sun Typically only seen close to the Sun, when they get very bright Allows much smaller comets to be seen Most are part of a “family” which all fragmented from a single “parent” comet Comets spread out in a chain along the orbit Have similar shaped orbits Arrive at the Sun at slightly different times


History of sungrazer discoveries : History of sungrazer discoveries Ground based discoveries (10-15) None since 1970 Space based: Solwind 1979-1985 (10) Solar Maximum Mission 1980-1989 (10) SOHO 1996-present (1137)


Prominent sungrazing comets : Prominent sungrazing comets


Sungrazing comets discovered by SOHO : Sungrazing comets discovered by SOHO Kreutz (948) Marsden (30) Meyer (70) Kracht (28) Kracht II (3) No family (51) Statistics as of 5/20/06


Slide10 : The above movie can be downloaded from http://lasco-www.nrl.navy.mil/mvimpg/xmas_c23_shrt_clean.mpg Other movies can be obtained from http://sohowww.nascom.nasa.gov/bestofsoho/Movies/movies2.html#comets


Slide11 : The above movie can be downloaded from http://lasco-www.nrl.navy.mil/movies/980411_c3_comet.mpg Other movies can be obtained from http://sohowww.nascom.nasa.gov/bestofsoho/Movies/movies2.html#comets


Kreutz group : Kreutz group Period ~800 years Highly inclined ~143º Pass the closest to the Sun Demonstrate the effects of higher temperatures and gravity than anything else in the Solar System Famous members: C/1843 D1 “The Great March Comet” C/1882 R1 “The Great September Comet” C/1965 S1 Ikeya-Seki


The Great March Comet (1843) : The Great March Comet (1843)


The Great September Comet (1882) : The Great September Comet (1882)


Ikeya-Seki (1965) : Ikeya-Seki (1965)


Prominent sungrazing comets : Prominent sungrazing comets


Prominent sungrazing comets : Prominent sungrazing comets


Marsden & Kracht groups : Marsden & Kracht groups Period ~5 years Related to: Comet 96P/Machholz Quadrantid (January) and Arietid (May-July) meteor shower Repeat observation allows measurement of erosion of comet’s nucleus Helps understand how long a comet lives


Other sungrazing comets : Other sungrazing comets Meyer group Very high inclination (72º) Kracht II group Predicted to have a period of ~4 years Next return in August 2006 Non-group comets Possibly more groups could be found


Comet discoveries in the future : Comet discoveries in the future SOHO will soon be replaced by STEREO Scheduled to launch in summer 2006 Two space-based coronagraphs which look at the Sun in stereo Will have a much larger field of view and will be sensitive to fainter comets Much better orbit determination than SOHO


Comet discoveries in the future : Comet discoveries in the future Next generation of surveys: Pan-STARRS Four 1.8-m telescopes in Hawaii Large Synoptic Survey Telescope (LSST) 8.4-m telescope in Chile Discovery Channel Telescope (DCT) 4.2-m telescope at Lowell Observatory, AZ


Want to get involved? : Want to get involved? You can search for sungrazing comets using publicly available data from SOHO: http://ares.nrl.navy.mil/sungrazer/ http://groups.yahoo.com/group/sohohunter/ http://www.sungrazer.org/