POLYCYCLIC AROMATIC HYDROCARBON EMISSION IN THE PROPLYD HST10: WHAT IS THE MECHANISM BEHIND PHOTOEVAPORATION?
- Kapteyn Astronomical Institute, Postbus 800, 9700 AV, Groningen (Netherlands)
- Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France)
- CAB (INTA-CSIC), LAEFF, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain)
- Laboratoire AIM, CEA/DSM - CNRS - Universite Paris Diderot, IRFU/SAP, F-91191 sur Yvette (France)
- UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France)
Proplyds are photodissociation-region-(PDR)-like cometary cocoons around young stars which are thought to originate through photoevaporation of the central protoplanetary disk by external UV radiation from the nearby OB stars. This Letter presents spatially resolved mid-infrared imaging and spectroscopy of the proplyd HST10 obtained with the Very Large Telescope/VISIR instrument. These observations allow us to detect polycyclic aromatic hydrocarbon (PAH) emission in the proplyd PDR and to study the general properties of PAHs in proplyds for the first time. We find that PAHs in HST10 are mostly neutral and at least 50 times less abundant than typical values found for the diffuse interstellar medium or the nearby Orion Bar. With such a low PAH abundance, photoelectric heating is significantly reduced. If this low abundance pertains also to the original disk material, gas heating rates could be too low to efficiently drive photoevaporation unless other processes can be identified. Alternatively, the model behind the formation of proplyds as evaporating disks may have to be revised.
- OSTI ID:
- 22130829
- Journal Information:
- Astrophysical Journal Letters, Vol. 765, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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