Volume 395, Number 2, November IV 2002
|Page(s)||L29 - L33|
|Published online||14 November 2002|
Letter to the Editor
Discovery of calcite in the solar type protostar NGC 1333-IRAS 4
Observatoire de Bordeaux, BP 89, 33270 Floirac, France
2 Laboratoire d'Astrophysique de l'Observatoire de Grenoble, France
3 CESR CNRS-UPS, BP 4346, 31028 Toulouse Cedex 04, France
4 SRON, PO Box 800, 9700 AV Groningen, The Netherlands
5 Astronomical Institute Anton Pannekoek, Univeristy of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
6 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001 Heverlee, Belgium
7 California Institute of Technology, Downs Laboratory of Physics 320-47, Pasadena, CA 91125, USA
Corresponding author: C. Ceccarelli, firstname.lastname@example.org
Accepted: 11 October 2002
We present observations, obtained with ISO-LWS, of the continuum between 50–200 μm of the solar type protostar IRAS 4, in the NGC 1333 complex. The continuum presents an excess, around 95 μm, that we demonstrate must be a dust feature. We compared the 95 μm excess with the calcite feature at 92 μm and find that it fits the observations reasonably well. There may be a further contribution from hydrous silicates at ~100 μm, but this seems a less robust result. The detected calcite mass is ~ and represents about 1% of the warm (~23 K) dust mass surrounding IRAS 4. This is only the second observation indicating the presence of carbonates outside the solar system, and the first revealing calcite in a young protostar. It is remarkable and intriguing that in all the objects where calcite has been detected so far, namely meteorites, planetary nebulae and IRAS 4, it represents from 0.3 to 1% of the dust mass. This new detection of calcite strengthens the claim by Kemper et al. (2002a) that calcite formation does not necessarely requires liquid water. We suggest that calcite forms at the surface of the grains, where water ice layers may locally have an enhanced mobility caused by heating due to hard X-rays emitted by the central object.
Key words: ISM: abundances / ISM: molecules / stars: formation / ISM: individual: IRAS 4
© ESO, 2002
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