Exocometary gas in the HD 181327 debris ring
Oxford University Press, 2016
academicJournal
Zugriff:
An increasing number of observations have shown that gaseous debris discs are not an exception. However, until now, we only knew of cases around A stars. Here we present the first detection of 12CO (2–1) disc emission around an F star, HD 181327, obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) observations at 1.3 mm. The continuum and CO emission are resolved into an axisymmetric disc with ring-like morphology. Using a Markov chain Monte Carlo method coupled with radiative transfer calculations, we study the dust and CO mass distribution. We find the dust is distributed in a ring with a radius of 86.0 ± 0.4 au and a radial width of 23.2 ± 1.0 au. At this frequency, the ring radius is smaller than in the optical, revealing grain size segregation expected due to radiation pressure. We also report on the detection of low-level continuum emission beyond the main ring out to ∼200 au. We model the CO emission in the non-local thermodynamic equilibrium regime and we find that the CO is co-located with the dust, with a total CO gas mass ranging between 1.2 × 10−6 M ⊕ and 2.9 × 10−6 M ⊕ , depending on the gas kinetic temperature and collisional partners densities. The CO densities and location suggest a secondary origin, i.e. released from icy planetesimals in the ring. We derive a CO+CO 2 cometary composition that is consistent with Solar system comets. Due to the low gas densities, it is unlikely that the gas is shaping the dust distribution.
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Exocometary gas in the HD 181327 debris ring
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Autor/in / Beteiligte Person: | Marino, S. ; Matrà, L. ; Stark, C. ; Wyatt, M. C. ; Casassus, S. ; Kennedy, G. ; Rodriguez, D. ; Zuckerman, B. ; Perez, S. ; Dent, W. R. F. ; Kuchner, M. ; Hughes, A. M. ; Schneider, G. ; Steele, A. ; Roberge, A. ; Donaldson, J. ; Nesvold, E. |
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Veröffentlichung: | Oxford University Press, 2016 |
Medientyp: | academicJournal |
DOI: | 10.1093/mnras/stw1216 |
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