596 Scheila

Overview

On 11 December 2010, Steve Larson of the Catalina Sky Survey detected a comet-like appearance to asteroid Scheila: it displayed a "coma" of about magnitude 13.5.{{cite web |name-list-style=amp |access-date=2010-12-12| archive-url= https://web.archive.org/web/20110107081344/http://remanzacco.blogspot.com/2010/12/comet-like-appearance-of-596-scheila.html| archive-date= 7 January 2011 | url-status= live}} Inspection of archival Catalina Sky Survey observations showed the activity was triggered between 11 November 2010 and 3 December.{{cite web |access-date=2010-12-12}} Imaging with the 2-meter Faulkes Telescope North revealed a linear tail in the anti-sunward direction and an orbital tail, indicative of larger slower particles.

When first detected it was unknown what drove the ejecta plumes. Scheila's gravity is too large for electrostatics to launch dust. Cometary outgassing could not be ruled out until detailed spectroscopic observations indicated the absence of gas in Scheila's plumes. Observations by the Hubble Space Telescope and the Neil Gehrels Swift Observatory's ultraviolet-optical telescope make it most likely that Scheila was impacted at ~5 km/s by a previously unknown asteroid ~35 meters in diameter.{{cite journal

As a consequence of the 2010 impact, the surface spectrum of Scheila changed, from a moderately red T-type spectrum to a more reddish D-type spectrum, showing how "fresh" material weathers over time in space. This is similar to laboratory experiments done on the Tagish Lake meteorite.

Scheila last came to perihelion on 2022 May 26.

References

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References

1. Schmadel, Lutz D.. (2003). "Dictionary of Minor Planet Names". Springer Science & Business Media.
2. Richard Miles's [https://archive.today/20120719231322/http://tech.groups.yahoo.com/group/mpml/message/24810 posting on Yahoo minor planet mailing list (MPML)]
3. (2022). "The Appearance of a "Fresh" Surface on 596 Scheila as a Consequence of the 2010 Impact Event". The Astrophysical Journal Letters.