Article Dans Une Revue The Astrophysical Journal Année : 2000

High-Resolution Hubble Space Telescope STIS Spectra of C I and CO in theβ Pictoris Circumstellar Disk

Résumé

High-resolution far-ultraviolet (FUV) echelle spectra showing absorption features arising from C I and CO gas in the β Pic circumstellar (CS) disk were obtained on 1997 December 6 and 19 using the Space Telescope Imaging Spectrograph (STIS). An unsaturated spin-forbidden line of C I at 1613.376 Å not previously seen in spectra of β Pic was detected, allowing for an improved determination of the column density of C I at zero velocity relative to the star (the stable component), N(3P)=(2-4)×1016 cm-2. Variable components with multiple velocities, which are the signatures of infalling bodies in the β Pic CS disk, are observed in the C I λλ1561 and 1657 multiplets. Also seen for the first time were two lines arising from the metastable 1D level of carbon at 1931 Å and 1463 Å. The results of analysis of the CO A-X (0-0), (1-0), and (2-0) bands are presented, including the bands arising from 13CO, with much better precision than has previously been possible, as a result of the very high resolution provided by the STIS echelle gratings. Only stable CO gas is observed, with a column density N(CO)=(6.3+/-0.3)×1014 cm-2. An unusual ratio of the column densities of 12CO to 13CO is found (R=15+/-2). The large difference between the column densities of C I and CO indicates that photodissociation of CO is not the primary source of C I gas in the disk, contrary to previous suggestion.

Dates et versions

hal-04110322 , version 1 (30-05-2023)

Identifiants

Citer

A. Roberge, P. D. Feldman, A. M. Lagrange, A. Vidal-Madjar, R. Ferlet, et al.. High-Resolution Hubble Space Telescope STIS Spectra of C I and CO in theβ Pictoris Circumstellar Disk. The Astrophysical Journal, 2000, 538, pp.904-910. ⟨10.1086/309157⟩. ⟨hal-04110322⟩
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