Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS 5-26555.
Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations★
Article first published online: 22 MAR 2011
© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
Monthly Notices of the Royal Astronomical Society
Volume 412, Issue 3, pages 1573–1590, April 2011
How to Cite
Lamy, P. L., Toth, I., Weaver, H. A., A'Hearn, M. F. and Jorda, L. (2011), Properties of the nuclei and comae of 10 ecliptic comets from Hubble Space Telescope multi-orbit observations. Monthly Notices of the Royal Astronomical Society, 412: 1573–1590. doi: 10.1111/j.1365-2966.2010.17934.x
- Issue published online: 4 APR 2011
- Article first published online: 22 MAR 2011
- Accepted 2010 October 26. Received 2010 October 26; in original form 2010 June 14
- comets: general
We report on our on-going effort to detect and characterize cometary nuclei with the Hubble Space Telescope (HST). During cycle 9 (2000 July to 2001 June), we performed multi-orbit observations of 10 ecliptic comets with the Wide Field Planetary Camera 2. Nominally, eight contiguous orbits covering a time interval of ∼11 h were devoted to each comet but a few orbits were occasionally lost. In addition to the standard R band, we could additionally observe four of them in the V band and the two brightest ones in the B band. Time series photometry was used to constrain the size, shape and rotational period of the 10 nuclei. Assuming a geometric albedo of 0.04 for the R band, a linear phase law with a coefficient of 0.04 mag deg−1 and an opposition effect similar to that of comet 19P/Borrelly, we determined the following mean values of the effective radii 47P/Ashbrook–Jackson: 2.86±0.08 km, 61P/Shajn–Schaldach: 0.62±0.02 km, 70P/Kojima: 1.83±0.05 km, 74P/Smirnova–Chernykh: 2.23±0.04 km, 76P/West–Kohoutek–Ikemura: 0.30±0.02 km, 82P/Gehrels 3: 0.69±0.02 km, 86P/Wild 3: 0.41±0.03 km, 87P/Bus: 0.270.01 km, 110P/Hartley 3: 2.15±0.04 km and 147P/Kushida–Muramatsu: 0.21±0.01 km. Because of the limited time coverage (∼11 h), the rotational periods could not be accurately determined, multiple solutions were sometime found and three periods were not constrained at all. Our estimates range from ∼5 to ∼32 h. The lower limits for the ratio a/b of the semi-axis of the equivalent spheroids range from 1.10 (70P) to 2.20 (87P). The four nuclei for which we could measure (V−R) are all significantly redder than the Sun, with 86P/Wild 3 (V−R) = 0.86 ± 0.10 appearing as an ultrared object. We finally determined the dust activity parameter Afρ of their coma in the R band, the colour indices and the reflectivity spectra of four of them.