Comet Lovejoy is still with us!

Rumours of the demise of Kreutz sungrazing Comet Lovejoy may have been greatly exaggarated.  NASA’s Solar Dynamics Observatory caught Comet Lovejoy emerging from its scorching close encounter with the sun.  [Video Credit: NASA SDO]

As the Science at Nasa press release notes

Comet Lovejoy was discovered on Dec. 2, 2011, by amateur astronomer Terry Lovejoy of Australia.  Researchers quickly realized that the new find was a member of the Kreutz family of sungrazing comets.  Named after the German astronomer Heinrich Kreutz, who first studied them, Kreutz sungrazers are fragments of a single giant comet that broke apart back in the 12th century (probably the Great Comet of 1106).  Kreutz sungrazers are typically small (~10 meters wide) and numerous. The Solar and Heliospheric Observatory sees one falling into the sun every few days.

At the time of discovery, Comet Lovejoy appeared to be at least ten times larger than the usual Kreutz sungrazer, somewhere in the in the 100 to 200 meter range.  In light of today’s events, researchers are re-thinking those numbers.

“I’d guess the comet’s core must have been at least 500 meters in diameter; otherwise it couldn’t have survived so much solar heating,” says Matthew Knight. “A significant fraction of that mass would have been lost during the encounter. The remains are probably much smaller.”

SOHO and NASA’s twin STEREO probes are monitoring the comet as it recedes from the sun. It is still very bright and should remain in range of the spacecrafts’ cameras for several days to come.

What happens next is anyone’s guess.

“There is still a possibility that Comet Lovejoy will start to fragment,” continues Battams. “It’s been through a tremendously traumatic event; structurally, it could be extremely weak. On the other hand, it could hold itself together and disappear back into the recesses of the solar system.”

And here’s an animated coronagraph image of Comet Lovejoy’s solar close encounter from SOHO.

Comet Lovejoy skimmed across the Sun’s edge about 140,000 km above the surface late Dec. 15 and early Dec. 16, 2011, furiously brightening and vaporizing as it approached the Sun. It is the brightest sungrazing comet that SOHO has ever seen, with a nucleus about twice as wide as a football field. It unexpectedly survived the pass and cruised out from behind the Sun some hours later. Comets are ancient balls of dust and ice. There is a temporary, four hour gap in the SOHO data after the comet went behind the occulting disk.

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  • That was great. What a wiggly tail!

  • Pete Baker

    Indeed, Joe.

    As the Science at Nasa press release also notes

    In the SDO movies, the comet’s tail wriggles wildly as the comet plunges through the sun’s hot atmosphere only 120,000 km above the stellar surface. This could be a sign that the comet was buffeted by plasma waves coursing through the corona. Or perhaps the tail was bouncing back and forth off great magnetic loops known to permeate the sun’s atmosphere. No one knows.

    “This is all new,” says Battams. “SDO is giving us our first look at comets travelling through the sun’s atmosphere. How the two interact is cutting-edge research.”

    “The motions of the comet material in the sun’s magnetic field are just fascinating,” adds SDO project scientist Dean Pesnell of the Goddard Space Flight Center. “The abrupt changes in direction reminded me of how the solar wind affected the tail of Comet Encke in 2007 (movie).”

  • fordprefect

    Fantastic! I love anything about astronomy, I’ve visited your threads on a right few occasions. We may not agree politically on a lot of things (if any), but we have a mutual love of the cosmos and all that goes on in it. Keep up the good work!