Spot­ted from afar: comet com­ing in from the cold

The Press and Journal (Inverness) - - NEWS -

Lead re­searcher Dr David Je­witt, from the Univer­sity of Cal­i­for­nia at Los An­ge­les, said: “K2 is so far from the sun and so cold, we know for sure that the ac­tiv­ity – all the fuzzy stuff mak­ing it look like a comet – is not pro­duced, as in other comets, by the evap­o­ra­tion of wa­ter ice.

“In­stead, we think the ac­tiv­ity is due to the sub­li­ma­tion (a solid chang­ing di­rectly into a gas) of su­per­volatiles as K2 makes its maiden en­try into the so­lar sys­tem’s plan­e­tary zone.

“That’s why it’s spe­cial. This comet is so far away and so in­cred­i­bly cold that wa­ter ice there is frozen like a rock.”

The Hub­ble ob­ser­va­tions sug­gest that sunlight is heat­ing frozen gases such as oxy­gen, ni­tro­gen, car­bon diox­ide, and car­bon monox­ide that coat the comet’s frigid sur­face.

As the icy volatiles lift off the comet they re­lease dust, form­ing the coma.

“Most comets are dis­cov­ered much closer to the sun, near Jupiter’s or­bit, so by the time we see them, these sur­face volatiles have al­ready been baked off. That’s why I think K2 is the most prim­i­tive comet we’ve seen,” added Dr Je­witt.

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