Journal Article

The return of activity in main-belt comet 133P/Elst–Pizarro

Henry H. Hsieh, David Jewitt, Pedro Lacerda, Stephen C. Lowry and Colin Snodgrass

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 403, issue 1, pages 363-377
Published in print March 2010 | ISSN: 0035-8711
Published online March 2010 | e-ISSN: 1365-2966 | DOI:
The return of activity in main-belt comet 133P/Elst–Pizarro

Show Summary Details


Comet 133P/Elst–Pizarro is the first known and currently best-characterized member of the main-belt comets, a recently identified class of objects that exhibit cometary activity but which are dynamically indistinguishable from main-belt asteroids. We report here on the results of a multiyear monitoring campaign from 2003 to 2008, and present observations of the return of activity in 2007. We find a pattern of activity consistent with seasonal activity modulation. Additionally, recomputation of phase function parameters using data in which 133P was inactive yields new IAU parameters of HR= 15.49 ± 0.05 mag and GR= 0.04 ± 0.05, and linear parameters of mR(1, 1, 0) = 15.80 ± 0.05 mag and β= 0.041 ± 0.005 mag deg−1. The comparison between predicted magnitudes using these new parameters and the comet's actual brightnesses during its 2002 and 2007 active periods reveals the presence of unresolved coma during both episodes, of the order of ∼0.20 of the nucleus cross-section in 2002 and ∼0.25 in 2007. Multifilter observations during 133P's 2007 active outburst yield mean nucleus colours of BV= 0.65 ± 0.03, VR= 0.36 ± 0.01 and RI= 0.32 ± 0.01, with no indication of significant rotational variation, and similar colours for the trail. Finally, while 133P's trail appears shorter and weaker in 2007 than in 2002, other measures of activity strength such as dust velocity and coma contamination of nucleus photometry are found to remain approximately constant. We attribute changes in trail strength to the timing of observations and projection effects, thus finding no evidence of any substantial decrease in the activity strength between 2002 and 2007.

Keywords: comets: general; comets: individual: 133P/Elst–Pizarro; minor planets, asteroids

Journal Article.  8140 words.  Illustrated.

Subjects: Astronomy and Astrophysics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.