Keck images dust around nova RS Oph

The Keck Interferometer combines light very carefully from the two 10m Keck telescope to do super high resolution imaging. They can run the interferometer in “nulling” mode to remove the effects of bright stars and study the much dimmer surrounding areas. It’s complicated stuff but it looks like the technique is capable of some pretty amazing results.

In this case it looks like they got lucky and were able to catch RS Oph, a recurrent nova, in outburst. The surprise was — the dust:

The nuller saw no dust in the bright zone, presumably because the nova’s blast wave vaporized dust particles. But farther from the white dwarf, at distances starting around 20 times the Earth-sun distance, the nuller recorded the spectral chemical signature of silicate dust. The blast wave had not yet reached this zone, so the dust must have pre-dated the explosion.

“This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” said Richard Barry of Goddard, lead author of the paper on the observations that will appear in the Astrophysical Journal.

The team thinks the dust is created as the white dwarf plows through the red giant’s wind, creating a pinwheel pattern of higher-density regions that is reminiscent of galaxy spiral arms.

Novae have been studied for a long time and we thought we had them pretty much figured out. If confirmed, this result could trigger a lot of activity in the variable star community.