August 26, 2019

27.01.11: A Surge of Sungrazers.

A curious event closed out the year 2010. From December 13th to the 22nd, astronomers studying the Sun noticed an unprecedented upswing in the number of sun diving comets. In fact, researchers spied no less than 25 comets in ten days, a record rate. The data comes from the European Space Agencies (ESA) Solar Heliospheric Observatory (SOHO) which has stared at the sun since its launch in 1996.

SOHO has a primary mission of studying the Sun, but catches comets periodically in its LASCO C2 and C3 cameras. This has led to tireless legions of amateur desktop astronomers pouring over frames and discovering more than 2,000 comets, many so tiny or close to the Sun that they probably would have gone unnoticed otherwise. The comets involved in the outburst were tiny, no more than 10 meters in size. Still, this leads astronomers to think that the proverbial “big one” may be yet to reveal itself. “It’s just a matter of time,” said researcher Karl Battams of the Naval Research Lab in Washington D.C. “We know that there are some big ones out there.”

Could a large sungrazing comet be inbound? The last one to put on such a show was Comet Ikeya-Seki in 1965. Ikeya-Seki buzzed the solar photosphere at a distance of 450,000 kilometers and then put on a splendid show on its outward journey as it was easily visible during the daytime. In fact, we haven’t had a good daylight comet since, and only the twin apparitions of comets Hyakutake and Hale-Bopp in the 1990’s came close. The nucleus of Ikeya-Seki was an estimated 5 kilometers in size and hence managed to survive its blazing passage.

All of the December 2010 fragments were members of the Kreutz family of comets. This family of comets was first identified by Heinrich Kreutz in the 19th century, and much of our modern thinking on this sub-familycomes from the late Brian Marsden, who passed away last year. Marsden had traced back the most likely progenitor of the Kreutz family of comets as a breakup of a single large comet around the 12th century. In fact, a bright daylight comet did occur around this era, the Great Comet of 1106 A.D.

Since the advent of SOHO, sungrazers have been studied in unprecedented detail. In fact, a 2008 PhD paper by Lowell observatories’ Matthew Knight reports 69 sun diving comets in 1997 versus the 200 seen in 2010…activity is definitely on the upswing.

So, are we due for a big “Comet of Century” appearance? Will it pop by just in time for 2012, to make folks shake a little bit? The orientation of the incoming path of Kreutz group comets is currently angled along the ecliptic towards the constellations of Capricornus and Aquarius in the dusk skies, and a large payoff might just be waiting for an avid comet hunter with the presence of mind to notice a fuzzy, out of place object. Good luck!

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