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Sungrazing Comets. (or How you can find comets without being a professional astronomer). Matthew Knight University of Maryland. Halley’s Comet. 1910. 1986. Hale-Bopp (1995). Hyakutake (1996). Kohoutek (1973). Tempel 1 (2005). SW3 (2006). What is a sungrazing comet?.
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Sungrazing Comets (or How you can find comets without being a professional astronomer) Matthew Knight University of Maryland
Halley’s Comet 1910 1986
Hale-Bopp (1995) Hyakutake (1996)
Tempel 1 (2005) SW3 (2006)
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 • Ground based discoveries (10-15) • None since 1970 • Space based: • Solwind 1979-1985 (10) • Solar Maximum Mission 1980-1989 (10) • SOHO 1996-present (1137)
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
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
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 • 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
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 • 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 • 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 • 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? • 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/