Open AccessAn infrared image of the dust disc around β Pic
Author(s) -
Heinrichsen I.,
Walker H. J.,
Klaas U.,
Sylvester R. J.,
Lemke D.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02325.x
Subject(s) - physics , astrophysics , photometry (optics) , infrared , black body radiation , emissivity , radius , radiative transfer , photometer , astronomy , stars , optics , computer security , radiation , computer science
The star β Pictoris is a normal main‐sequence star with a remnant disc of cool dust around it. We present observations of the β Pic dust disc in the far‐infrared, obtained using the photometer (ISOPHOT) on the Infrared Space Observatory (ISO) satellite. We resolve the edge‐on disc using high‐resolution scans, with full widths at half‐maximum of 8.7 × 2.9 arcsec 2 (± 1.5 arcsec) at 25 μ m (corresponding to a characteristic disc radius of 84 au) and 14.5 × 6.1 arcsec 2 (± 2.0 arcsec) at 60 μ m (corresponding to 140 au). The disc is just resolved in the minor axis direction at 60 μ m. Photometry, from 4.85 to 200 μ m, is combined with low‐resolution spectroscopy and modelled to give an average dust temperature of 85 K, using a blackbody modified by an emissivity proportional to λ ‐1 . A simple radiative transfer model is also used, with the grain radius ranging from 1 μ m to 5 mm. The dust mass is estimated to be around (3‐‐10) × 10 ‐8 M ⊙ (0.9‐‐2.7 M moon ), depending on the selected grain parameters.