Astron. Astrophys. 343, L87-L90 (1999)

4. Conclusions

In the present work we have reported the infrared spectrum of comet 103P/Hartley 2, observed with the medium resolution ISOPHOT-S instrument on 1 Jan. 1998. The analysis of the 2.5-5 µm range evidences relevant spectral features. Vibrational bands of water (2.66 µm) and carbon dioxide (4.26 µm) were both directly measured by infrared spectroscopy for this comet. A strong out-gassing of carbon dioxide was observed, leading to confirm a CO₂/H₂O ratio of about 8%, consistent with data inferred from UV observations. A feature at 3.69 µm appears difficult to attribute clearly. The 6-12 µm spectrum is well fitted by a blackbody emission at a colour temperature of 285 K.

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999
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