14 January 2018

Comet PanSTARRS ~ Space Weather ~ 13 January 2018

(It's blue....)

Source: Space Weather


Astronomers are marveling at the wild blue color and even wilder dynamics of Comet PanSTARRS (C/2016 R2), now approaching the sun beyond the orbit of Mars. Every day, it seems, another cloud of dusty gas billows down the comet's tail as gaseous jets swivel around the comet's core. This is what the comet looked like on Jan. 10th: (see image above)

Amateur astronomer Gerald Rhemann took the picture from his private observatory in Farm Tivoli, Namibia. "This is a 56 minute guided exposure through a 12-inch telescope," he explains.

The comet's extraordinary behavior can be traced to one key ingredient: carbon monoxide (CO). The comet's core is spewing 4.7 x 1028 CO molecules into space every second, according to recent measurements at the Arizona Radio Observatory's 10-m Submillimeter Telescope. This accounts for the comet's lovely color (because ionized CO glows blue) and its hyperactivity. Carbon monoxide is extremely volatile. CO can sublimate (change suddenly from solid to gas) at temperatures as low as -248 C (25 K). Only a little bit of sunlight is required to turn deposits of frozen CO into wild jets and billowing clouds.

Where did all this CO come from?

Many readers have asked this question, assuming perhaps that carbon monoxide is rare. On the contrary, carbon monoxide is one of the most common molecules found in interstellar space. Only diatomic hydrogen (H2) is more abundant. A quick look at the most common elements in the cosmos explains why:

Carbon and oxygen are among the most abundant atoms, second only to hydrogen and helium. C and O are cooked up inside stars via nucleosynthesis and scattered throughout space by stellar explosions. These species naturally get together to form CO. Interstellar CO was first detected with radio telescopes in 1970, and it is now a commonly used tracer of molecular gas in distant galaxies. It is hardly surprising that we occasionally find stores of this material inside comets--in this case, Comet PanSTARRS.

What will this CO-rich comet look like tomorrow? Stay tuned!

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