| Name | OT1_cjoblin_1 |
| Title | Physics of gas evaporation at PDR edges |
| URL | http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342213713&instrument_name=HIFI&product_level=LEVEL0&compress=true |
| DOI | https://doi.org/10.5270/esa-519ej9v |
| Author | European Space Agency |
| Description | Far-ultraviolet (FUV) photons in massive OB star-forming regions have a major impact on the structure, dynamics, chemistry and thermal balance of their associated molecular cloud. We propose to study the photoevaporation under FUV irradiation of dense filaments in prototype photodissociation regions (PDR) by mapping with the HIFI spectrometer the [CII] 158 micron line associated with the evaporating gas and high-J CO lines tracing the warm dense structures. The combination of the spectral range covered by Herschel and the very high spectral resolution of HIFI is unique to get insight into the process of mixing of cold molecular gas into warm atomic gas. This process governs the evolution of dense gas submitted to FUV photons in a wide variety of astronomical objects including protostellar and protoplanetary disks but is best studied in PDRs. We ask for 9.8 hours of observations in two PDRs, NGC7023 and the Horsehead nebula. NGC7023 is illuminated by a B2Ve star and hosts very diluted atomic gas and dense filaments. The Horsehead nebula is a PDR viewed nearly edge-on with a high gas density gradient at the edge that is illuminated by a O9.5V star and is immersed in an HII region. In these objects, there is evidence for dynamical processes that create a mixing layer between molecular and atomic gas, both from gas kinematics (first results with HIFI on the [CII] line) and chemistry. The first HIFI [CII] results clearly call for a larger spatial coverage of the region using OTF mapping mode with HIFI to obtain a more complete picture of the PDR morphology and dynamics. The 12^CO(8-7) and 13^CO(8-7) lines will be also targeted to trace the warm interfaces of the dense filaments/edges. The team gathers together specialists of the studied regions and of the Herschel instruments: HIFI (this proposal), SPIRE and PACS (comple...mentary data). The team has strong expertise in the study of the physics and chemistry of PDRs, both in terms of data analysis and modelling using and developing the Meudon PDR code. |
| Publication | |
| Instrument | HIFI_HifiMapping_load-raster, HIFI_HifiMapping_fly |
| Temporal Coverage | 2011-02-03T22:17:13Z/2012-04-14T09:41:29Z |
| Version | SPG v14.1.0 |
| Mission Description | 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. |
| Creator Contact | https://support.cosmos.esa.int/h®erschel/ |
| Date Published | 2012-10-14T08:09:13Z |
| Publisher And Registrant | European Space Agency |
| Credit Guidelines | European Space Agency, 2012, Physics Of Gas Evaporation At Pdr Edges, SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-519ej9v |