|A Herschel survey of photodissociation regions in proplyds
|Most low mass stars form near OB associations and are hence subject to the harsh feedback of massive stars. Proplyds are in this situation. They are young stars, surrounded by a protoplanetary disk which is being photo-evaporated by the far-UV (FUV) photons emitted by massive stars. This photo-evaporation process determines the mass-loss and hence lifetime of these disks, which may result in severe constraints on the planet formation timescale. The photo-evaporation flow results from the formation of a photodissocaition region (PDR) at the surface of the disk, where FUV photons heat the atomic and molecular gas. The bright far-infrared cooling lines of atomic and molecular gas, observable with Herschel, are therefore the ideal tracers to understand the mechanisms at play in the PDRs at the surface of the disks. Unfortunately, proplyds have not been observed with Herschel. With this proposal, we will obtain key cooling lines -- [OI], [CII] and high J CO-- emitted by the dense and highly irradiated PDRs of three carefully selected proplyds in the Orion and Carina Nebulae. We will then analyze these observations in the frame of PDR and disk models, in order to provide a clearer picture of the photoevaporation process. For these observations we require 10.3 hours.
|Herschel survey and modelling of externally-illuminated photoevaporating protoplanetary disks . Champion J. et al. . Astronomy & Astrophysics, Volume 604, id.A69, 23 pp. . 604 . 10.1051/0004-6361/201629404 . 2017A&A...604A..69C ,
|HIFI_HifiPoint_dbs, HIFI_HifiPoint_fs, HIFI_HifiPoint_load, PACS_PacsLineSpec_point
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_oberne_4, SPG v14.2.0. https://doi.org/10.5270/esa-lyjkz4o