Swift ultraviolet photometry of the Deep Impact encounter with Comet 9P/Tempel 1

K. O. Mason, M. Chester, A. Cucchiara, C. Gronwall, D. Grupe, S. Hunsberger, G. H. Jones, S. Koch, J. Nousek, P. T. O'Brien, J. Racusin, P. Roming, P. Smith, A. Wells, R. Willingale, G. Branduardi-Raymont, N. Gehrels

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We report time-resolved imaging UV photometry of Comet 9P/Tempel 1 during the interval 2005 June 29-2005 July 21, including intensive coverage of the collision with the Deep Impact probe and its immediate aftermath. The nuclear flux of the comet begins to rise within minutes of the collision, and peaks about 3 h after impact. There is no evidence for a prompt flash at the time of impact. The comet exhibits a significant re-brightening about 40 h after the initial outburst, consistent with the rotation period of the comet, with evidence for further periodic re-brightenings on subsequent rotations. Modelling of the brightness profile of the coma as a function of time suggests two distinct velocity systems in the ejecta, at de-projected expansion speeds of 190 and 550 m/s, which we suggest are due to dust and gas, respectively. There is a distinct asymmetry in the slower-moving (dust) component as a function of position angle on the sky. This is confirmed by direct imaging analysis, which reveals an expanding plume of material concentrated in the impact hemisphere. The projected expansion velocity of the leading edge of this plume, measured directly from the imaging data, is 190 m/s, consistent with the velocity of the dust component determined from the photometric analysis. From our data we determine that a total of (1.4 ± 0.2) × 1032 water molecules were ejected in the impact, together with a total scattering area of dust at 300 nm of 190 ± 20   km2.

Original languageEnglish (US)
Pages (from-to)123-131
Number of pages9
JournalIcarus
Volume187
Issue number1
DOIs
StatePublished - Mar 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Swift ultraviolet photometry of the Deep Impact encounter with Comet 9P/Tempel 1'. Together they form a unique fingerprint.

  • Cite this

    Mason, K. O., Chester, M., Cucchiara, A., Gronwall, C., Grupe, D., Hunsberger, S., Jones, G. H., Koch, S., Nousek, J., O'Brien, P. T., Racusin, J., Roming, P., Smith, P., Wells, A., Willingale, R., Branduardi-Raymont, G., & Gehrels, N. (2007). Swift ultraviolet photometry of the Deep Impact encounter with Comet 9P/Tempel 1. Icarus, 187(1), 123-131. https://doi.org/10.1016/j.icarus.2006.09.021