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RE: Comet
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Constant Comet Threat
It certainly captures the imagination: a star passing silently by our solar system knocks a deadly barrage of comets towards Earth. However, recent simulations by one group of researchers has shown that these star-induced comet showers may not be as dramatic as once thought.
The idea of nearby stars influencing comets goes back to 1950, when the astronomer Jan Hendrik Oort hypothesized an invisible repository of comets - the so-called Oort cloud - swarming around the solar system out to a distance of 100,000 AU (one AU is the distance between the sun and the Earth).
Oort assumed that stars passing through the cloud would cause a fresh batch of comets to fall in towards the sun, where they become visible to astronomers. Such a disturbance could have long term effects.

"The comets we see now could be from a stellar passage hundreds of millions of years ago" - Hans Rickman of the Uppsala Astronomical Observatory.

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Swift Looks to Comets for a Cool View
NASA's Swift Gamma-ray Explorer satellite rocketed into space in 2004 on a mission to study some of the highest-energy events in the universe. The spacecraft has detected more than 380 gamma-ray bursts, fleeting flares that likely signal the birth of a black hole in the distant universe. In that time, Swift also has observed 80 exploding stars and studied six comets.
Comets?... Comets are 'dirty snowballs' made of frozen gases mixed with dust. X-rays come from superhot plasmas. What do cold comets have in common with exploding stars or the birth of black holes?

"It was a big surprise in 1996 when the NASA-European ROSAT mission showed that comet Hyakutake was emitting X-rays. After that discovery, astronomers searched through ROSAT archives. It turns out that most comets emit X-rays when they come within about three times Earth's distance from the sun" - Dennis Bodewits, a NASA Postdoctural Fellow at the Goddard Space Flight Centre in Greenbelt, Md.

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Seven new comets were discovered on images taken by the SOHO satellite, and announced by in the  MPEC 2008-L18 and MPEC 2008-L19 news pages.
The comet C/2008 C9 does not seem to belong to any known group,  comet C/2008 D6 belongs to the Meyer group, while the other comets belong to the Kreutz group.

C/2008 C6 (SOHO) Bo Zhou
C/2008 C7 (SOHO) Hua Su
C/2008 C8 (SOHO) John Sachs
C/2008 C9 (SOHO) Rainer Kracht
MPEC 2008-L18

C/2008 D5 (SOHO) Hua Su
C/2008 D6 (SOHO) Tony Hoffman
C/2008 D7 (SOHO) Bo Zhou
MPEC 2008-L19



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Two new comets discovered on SECCHI images  taken by the  HI1-A instrument  aboard the STEREO-A satellite  were announced by the  MPEC 2008-K29 circular.

C/2008 E5 (STEREO) - Alan Watson
C/2008 E6 (STEREO) - Rainer Kracht

The two STEREO comets belong to the Kreutz group.

MPEC 2008-K29

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SOHO Comets
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Seven new comets were discovered on archived images taken by the SOHO satellite.
The comets ere announced on circulars MPEC 2008-G59 and MPEC 2008-G60.
Comet C/2008 C3 does not belong to any known group; the other comets belong to the Kreutz group.

C/2008 B1 (SOHO) Hua Su
C/2008 B2 (SOHO) Arkadiusz Kubczak
C/2008 B3 (SOHO) Hua Su
C/2008 B4 (SOHO) Bo Zhou
MPEC 2008-G59

C/2008 C3 (SOHO) Rainer Kracht
C/2008 C4 (SOHO) Hua Su
C/2008 C5 (SOHO) Arkadiusz Kubczak
MPEC 2008-G60



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RE: Comet
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Three new comets were discovered on archived images taken by the SOHO satellite.
The results for comet C/2002 are repeat observations announced on circulars MPEC 2002-Q46 and MPC 46495.
There is a possible link between the comets C/2008 Q8 and C/2008 E4 suggested by initial measurements (MPEC 2002-Q46). Repeat measurements did not find the comet on the images taken on February 14.9, 1997, during perihelion.
The comets C/2002 Q8 and C/2008 E4 belong to the Kracht group, while the comet C/2008 F1 belongs to the Meyer group.

C/2002 Q8 (SOHO) Xingming Zhou
C/2008 E4 (SOHO) Hua Su
C/2008 F1 (SOHO) Rainer Kracht

MPEC 2008-F32



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Four  new comets were discovered on archived images taken by the SOHO satellite.
The comet C/2007 Y8 belongs to the  Meyer group. The comets C/2007 Y9 and C/2007 Y10 belong to the Kreutz group; the comet C/2008 A3, from the Marsden group, was successfully linked to comet C/2002 R1, by  R. Kracht.

C/2007 Y8 (SOHO) Rainer Kracht
C/2007 Y9 (SOHO) Rob Matson
C/2007 Y10 (SOHO) Bo Zhou
C/2008 A3 (SOHO) Rainer Kracht
MPEC 2008-B61



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Seven new comets were discovered on archived images taken by the SOHO satellite.
The comet C/2007 X14 belongs to the  Meyer group;  the comet C/2007 Y4  could be the return of the comet C/2002 R4, and  belongs to the Marsden   group; the others belong to the  Kreutz group.

C/2007 X14 (SOHO) Tony Hoffman
C/2007 X15 (SOHO) Hua Su
MPEC 2008-B48

C/2007 Y3 (SOHO) Shihong Yuan, Tony Hoffman
C/2007 Y4 (SOHO) Rainer Kracht
C/2007 Y5 (SOHO) Arkadiusz Kubczak
C/2007 Y6 (SOHO) Shihong Yuan
C/2007 Y7 (SOHO) Hua Su, Rainer Kracht, Shihong Yuan
MPEC 2008-B49



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Eight new comets were discovered on archived images taken by the SOHO satellite.
The comet C/2007 X7 belongs to the  Meyer group,  the others belong to the  Kreutz group.

C/2007 X6 (SOHO) Michal Kusiak
C/2007 X7 (SOHO) Hua Su
C/2007 X8 (SOHO) Tony Hoffman
C/2007 X9 (SOHO) Rob Matson, Tony Hoffman
MPEC 2008-B45

C/2007 X10 (SOHO) Tony Hoffman
C/2007 X11 (SOHO) Rainer Kracht, Hua Su
C/2007 X12 (SOHO) Rob Matson
C/2007 X13 (SOHO) Parrish Collison, Tony Hoffman
MPEC 2008-B46



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