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