Sungrazing Comets or How you can find comets

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) SW 3 (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)

Prominent sungrazing comets Year 372 BC 1106 1843 Comet name/discoverer Ephorus/Aristotle Europe, China, Japan, Korea, Constantinople, Palestine Great March Comet 1880 1882 1887 1945 1963 1965 1970 Great Southern Comet Eclipse Comet aka. “Tewfik” Great September Comet Great Southern Comet du Toit Pereyra Ikeya-Seki White-Ortiz-Bolelli

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_c 23_shrt_clean. mpg Other movies can be obtained from http: //sohowww. nascom. nasa. gov/bestofsoho/Movies/movies 2. html#comets

The above movie can be downloaded from http: //lasco-www. nrl. navy. mil/movies/980411_c 3_comet. mpg Other movies can be obtained from http: //sohowww. nascom. nasa. gov/bestofsoho/Movies/movies 2. 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 D 1 “The Great March Comet” – C/1882 R 1 “The Great September Comet” – C/1965 S 1 Ikeya-Seki

The Great March Comet (1843)

The Great September Comet (1882)

Ikeya-Seki (1965)

Prominent sungrazing comets Year 372 BC 1106 1843 Comet name/discoverer Ephorus/Aristotle Europe, China, Japan, Korea, Constantinople, Palestine Great March Comet 1880 1882 1887 1945 1963 1965 1970 Great Southern Comet Eclipse Comet aka. “Tewfik” Great September Comet Great Southern Comet du Toit Pereyra Ikeya-Seki White-Ortiz-Bolelli

Prominent sungrazing comets Year 372 BC 1106 Comet name/discoverer Ephorus/Aristotle Europe, China, Japan, Korea, Constantinople, Palestine 1843 Great March Comet 1880 1882 1887 1945 1963 1965 1970 Great Southern Comet Eclipse Comet aka. “Tewfik” Great September Comet Great Southern Comet du Toit Pereyra Ikeya-Seki White-Ortiz-Bolelli

Marsden & Kracht groups • Period ~5 years • Related to: – Comet 96 P/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/