Letter to the Editor
Infrared spectral observations of comet 103P/Hartley 2 by ISOPHOT *
L. Colangeli 1,
E. Epifani 1,2,
J.R. Brucato 1,
E. Bussoletti 3,
C. DeSanctis 4,
M. Fulle 5,
V. Mennella 1,
E. Palomba 1,6,
P. Palumbo 3 and
A. Rotundi 3
Received 15 December 1998 / Accepted 14 February 1999
Spectral observations in the 2.5-12 µm range of comet 103P/Hartley 2 were performed on 1 Jan. 1998 by the ISOPHOT instrument, on board the Infrared Space Observatory. The obtained spectrum evidences intense bands at 2.66 and 4.26 µm, attributable to H2O and CO2, respectively. The derived molecular production rates are Q(H2O) = (3.1 0.2) 1028 molec. s-1 and Q(CO2) = (2.5 0.3) 1027 molec. s-1. This leads to a CO2/H2O abundance ratio of 8%, showing that P/Hartley 2 is a relatively CO2 abundant comet, with respect to 1P/Halley and several other comets. A feature has been detected at 3.69 µm, whose attribution is rather puzzling. The long wavelength part of the spectrum is well fitted by a black-body profile at 285 K colour temperature. No significant silicate emission feature around 10 µm is observed, within observation errors.
Key words: comets: individual: 103P/Hartley 2 infrared: solar system
* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with participation of ISAS and NASA.
Send offprint requests to: L. Colangeli
This article contains no SIMBAD objects.
© European Southern Observatory (ESO) 1999
Online publication: March 1, 1999