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Title: PROBING THE RADIAL TEMPERATURE STRUCTURE OF PROTOPLANETARY DISKS WITH HERSCHEL/HIFI

Herschel/HIFI spectroscopic observations of CO J = 10-9, CO J = 16-15 and [C II] toward HD 100546 are presented. The objective is to resolve the velocity profile of the lines to address the emitting region of the transitions and directly probe the distribution of warm gas in the disk. The spectra reveal double-peaked CO line profiles centered on the systemic velocity, consistent with a disk origin. The J = 16-15 line profile is broader than that of the J = 10-9 line, which in turn is broader than those of lower-J transitions (6-5, 3-2, observed with APEX), thus showing a clear temperature gradient of the gas with radius. A power-law flat disk model is used to fit the CO line profiles and the CO rotational ladder simultaneously, yielding a temperature of T {sub 0} = 1100 ± 350 K (at r {sub 0} = 13 AU) and an index of q = 0.85 ± 0.1 for the temperature radial gradient. This indicates that the gas has a steeper radial temperature gradient than the dust (mean q {sub dust} ∼ 0.5), providing further proof of the thermal decoupling of gas and dust at the disk heights where the CO linesmore » form. The [C II] line profile shows a strong single-peaked profile red-shifted by 0.5 km s{sup –1} compared to the systemic velocity. We conclude that the bulk of the [C II] emission has a non-disk origin (e.g., remnant envelope or diffuse cloud)« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Max Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)
  2. Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)
  3. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 78, Cambridge, MA 02138 (United States)
  5. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22215401
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 776; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLOUDS; COMPARATIVE EVALUATIONS; COSMIC DUST; EMISSION; PEAKS; PROBES; PROTOPLANETS; RED SHIFT; SPECTRA; TEMPERATURE GRADIENTS; VELOCITY