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Astron. Astrophys. 354, 965-982 (2000)

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Far-infrared photometry and mapping of Herbig Ae/Be stars with ISO *

P. Ábrahám 1,2, Ch. Leinert 1, A. Burkert 3, Th. Henning 3 and D. Lemke 1

1 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
2 Konkoly Observatory of the Hungarian Academy of Sciences, P.O.Box 67, 1525 Budapest, Hungary
3 Astrophysikalisches Institut und Universitäts-Sternwarte, Schillergäßchen 3, 07745 Jena, Germany

Received 23 August 1999 / Accepted 8 December 1999

Abstract

Seven Herbig Ae/Be stars were observed at mid- and far-infrared wavelengths with ISOPHOT, the photometer on-board the Infrared Space Observatory. At [FORMULA]m, where the emission mainly arises from a compact circumstellar region, the observed spectral energy distributions can be described by power-law relationships between wavelength and flux density ([FORMULA]). The exponent of the power-law changes considerably among the stars, from [FORMULA] for MWC 1080 to [FORMULA] in the case of LkH[FORMULA] 234, with a typical value of around 1. Interpreting the observed power-law relationships in terms of circumstellar disks, in 5 out of 6 cases relatively shallow radial temperature distributions have to be assumed ([FORMULA] where [FORMULA]). At longer wavelengths the observed emission is spatially extended, and in some cases significant discrepancy with IRAS was found due to beam size effects. The peak of the SEDs (in [FORMULA]) is typically at 60-100µm, corresponding to temperatures of around 50 K. At [FORMULA]m the emission observed by ISOPHOT is never dominated by the Herbig Ae/Be stars. The most likely sources of the far-infrared radiation are dust cores of about 1 arcminute in size. The dust cores are probably located in the vicinity of the stars, and may be related to the star forming process.

Key words: stars: formation – stars: pre-main sequence – ISM: clouds – ISM: dust, extinction – radio continuum: ISM – stars: circumstellar matter

* Based on observations with ISO, an ESA project with instruments funded by ESA member states (especially the P/I countries France, Germany, the Netherlands and the United Kingdom) with participation of ISAS and NASA.

Send offprint requests to: P. Ábrahám, Heidelberg

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© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000
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