A new comet is currently making its inaugural trip to the inner Solar System from the Oort cloud where it likely originated. New images show a tremendous amount of dust streaming away from it, along with strange blobs that have attracted the attention of astronomers.

The comet is currently being investigated by Johns Hopkins physicist Nour E. Raouafi, who was scanning the Sun with the SECCHI/HI-1 telescope aboard the solar-observing spacecraft STEREO-B. He was looking for coronal mass ejections (CMEs) when comet C/2011 L4 (Pan-STARRS) came into his field of view, which he described as an “amazing” sight.

The comet, in addition to being unusually dusty, appears to be jettisoning weird clumps. Not being a comet researcher, Raouafi recruited the help of JHUAPL astrophysicist Casey Lisse who was likewise intrigued. Their analysis of the comet and its mysterious clumps can be found in the latest issue of Geophysical Research—Space Physics.

So what are the clumps? Larry O’Hanlon from the American Geophysical Union explains:

Since the clumps are moving directly away from sun, it appears they are being driven by the solar wind. The clumps are flowing past the comet at typical speeds of 250 to 500 kilometers per second (about 155 to 310 miles per second). This is about the same speed as the solar wind, suggesting the clumps are very small, lightweight particles or gas, according to the new study.

The fact that the clumps do not change in size as they blow away suggests they are being held together by the magnetic field of the solar wind. This means they are likely charged particles, or ionized gas, which are sensitive to magnetic fields. Likely candidates are ionized potassium and sodium that have been roasted out of the rocks on the comet as it passes close to the sun, according to the researchers.


Another possibility is that the clumps are dust in the process of exploding. If true, this could explain why comet tails have lines, or straie, that make them appear as if they’ve been combed.

Read the entire study at Geophysical Research—Space Physics: “Dynamics of HVECs emitted from comet C/2011 L4 as observed by STEREO”.

[ AGU ]

Contact the author at george@io9.com and @dvorsky. Top image by AGU