| Issue |
A&A
Volume 419, Number 1, May III 2004
|
|
|---|---|---|
| Page(s) | 375 - 383 | |
| Section | Planets and planetary systems | |
| DOI | https://doi.org/10.1051/0004-6361:20040073 | |
| Published online | 23 April 2004 | |
The nuclei of comets 126P/IRAS and 103P/Hartley 2*
1
Laboratoire d'Astronomie Spatiale, BP 8, 13376 Marseille Cedex 12, France
2
Konkoly Observatory, PO Box 67, Budapest 1525, Hungary
Corresponding author: O. Groussin, grousssin@astro.umd.edu
Received:
6
May
2003
Accepted:
15
January
2004
We report the detection of the nucleus of 126P/IRAS and
103P/Hartley 2 with the Infrared Camera of the Infrared Space
Observatory (ISOCAM). 126P/IRAS was observed on 12 November 1996,
when it was at 
AU from the Sun and
AU from the
Earth. 103P/Hartley 2 was observed on 5 February 1998, when it was
at 
AU from the Sun and 
AU from
the Earth. The observations were performed with the broadband LW10
filter centered at 11.5 μm. The spatial resolution was
adequate to separate the thermal emission of the nuclei from that of
their respective comae. We combined the ISOCAM observations with
measured water production rates, using a model that considers a
spherical nucleus with a macroscopic mosaic of small and numerous
active and inactive regions, and we derived a radius of
km and an active fraction at perihelion of
for 126P/IRAS, and a radius of
km and an active fraction of ~1 at perihelion
and 
at 1.11 AU post-perihelion for 103P/Hartley 2.
These two examples illustrate the large diversity of activity pattern
that exists among cometary nuclei.
Key words: comets: individual: 126P/IRAS / comets: individual: 103P/Hartley 2 / comets: general
© ESO, 2004
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