EDP Sciences
Free Access
Volume 432, Number 2, March III 2005
Page(s) 547 - 557
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20041891

A&A 432, 547-557 (2005)
DOI: 10.1051/0004-6361:20041891

The 90-110 $\mu$m dust feature in low to intermediate mass protostars: Calcite?

A. Chiavassa1, C. Ceccarelli1, A. G. G. M. Tielens2, E. Caux3 and S. Maret1

1  Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 09, France
    e-mail: cecilia.ceccarelli@obs.ujf-grenoble.fr
2  Kapteyn Astronomical Instute, BO Box 800, 9700 AV Groningen, The Netherlands
3  CESR CNRS - UPS, BP 4346, 31028, Toulouse Cedex 04, France

(Received 24 August 2004 / Accepted 25 October 2004)

We present ISO spectra between 60 and 180 $\mu$m of 32 protostars of low to intermediate mass. About half of the spectra present a dust feature between ~90 and ~110 $\mu$m. We describe the observational characteristics of this feature, which seems to be due to one single carrier. In Class 0 sources the feature peaks around 100 $\mu$m, while in AeBe stars it peaks around 95 $\mu$m. The feature peak position seems to mostly depend on the temperature of the dust of the source, suggesting reprocessing of the dust. We present arguments for the identification of the observed feature as due to calcite, and estimate that about 10% to 30% of elemental Ca is locked up in it. Therefore, calcite seems to be formed relatively easily around protostars despite the observation that on Earth it needs aqueous solutions. This rises the question of whether conditions simulating liquid water are common around forming stars and what creates them.

Key words: ISM: abundances -- ISM: molecules -- stars: formation -- ISM: dust, extinction -- ISM: lines and bands -- infrared: ISM

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