The circumstellar envelope of the C-rich post-AGB star HD 56126
| dc.creator | Hony, S. | |
| dc.creator | Tielens, A. G. G. M. | |
| dc.creator | Waters, L. B. F. M. | |
| dc.creator | de Koter, A. | |
| dc.date | 2003-02-21 | |
| dc.date.accessioned | 2026-07-07T10:26:52Z | |
| dc.date.available | 2026-07-07T10:26:52Z | |
| dc.description | We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch ``21 micron object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use amorphous carbon, hydrogenated amorphous carbon, magnesium sulfide and titanium carbide. We present a detailed parametrisation of the optical properties of hydrogenated amorphous carbon as a function of H/C content. The mid-infrared imaging and spectroscopy is best reproduced by a single dust shell from 1.2 to 2.6 arcsec radius around the central star. This shell originates from a short period during which the mass-loss rate exceeded 10^(-4) M_sun/yr. We find that the strength of the ``21'' micron feature poses a problem for the TiC identification. The low abundance of Ti requires very high absorption cross-sections in the ultraviolet and visible wavelength range to explain the strength of the feature. Other nano-crystalline metal carbides should be considered as well. We find that hydrogenated amorphous carbon in radiative equilibrium with the local radiation field does not reach a high enough temperature to explain the strength of the 3.3-3.4 and 6-9 micron hydrocarbon features relative to the 11-17 micron hydrocarbon features. We propose that the carriers of these hydrocarbon features are not in radiative equilibrium but are transiently heated to high temperature. We find that 2 per cent of the dust mass is required to explain the strength of the ``30'' micron feature, which fits well within the measured atmospheric abundance of Mg and S. This further strengthens the MgS identification of the ``30'' micron feature. | |
| dc.description | 20 Pages, 10 Figures, accepted for publication in Astronomy and Astrophysics | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0302448 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0302448 | |
| dc.identifier | Astron.Astrophys.402:211-228,2003 | |
| dc.identifier | doi:10.1051/0004-6361:20030240 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/176991 | |
| dc.subject | Astrophysics | |
| dc.title | The circumstellar envelope of the C-rich post-AGB star HD 56126 | |
| dc.type | text |