| Name | OT2_ppilleri_1 |
| Title | Dynamics of the ultracompact HII region Monoceros R2: solving the lifetime paradox of young massive star forming region |
| URL | http://archives.esac.esa.int/hsa/whsa-tap-server/data?retrieval_type=OBSERVATION&observation_id=1342250693&instrument_name=HIFI&product_level=LEVEL0&compress=true |
| DOI | https://doi.org/10.5270/esa-iis2qyc |
| Author | pilleri, p. |
| Description | Ultracompact (UC) HII regions represent one of the earliest phasesin massive star formation. They are characterized by extremeUV irradiation (G0>10^5 Habings), small physicalscales (<0.1 pc) and are embedded in dense molecular clouds.HII regions are expected to expand at velocities of the order of the sound speed (10km/s) and remain ultracompact for about 3000 years. Therefore, only a few dozen should exist in the Galaxy. However, many more UCHIIs have been observed,corresponding to lifetimes one to two orders of magnitude larger.A number of models have been proposed to solve this problem, but all haveshortcomings. Our ability to test these models depends on goodinformations about the morphology and the kinematics of the sources.Mon R2 is the closest ultracompact HII region (d=830 pc), the only one thatcan be resolved by Herschel and undoubtedly a case study.Full modeling of the CO lines previously observed with HIFIsuggests that the high velocity gas arises from the layer of warm (>100 K) and dense(>5x10^6 cm-3) gas confining the UCHII region. The line profiles are well reproducedassuming that this layer is expanding at the relatively high velocity of1.5km/s, corresponding to a lifetime of about 10^5 years. Our kinematical study of the region is however limitedby the scarce HIFI observations that hinder a full 3Dmodeling.We propose to observe with HIFI fully sampled maps of several atomicand molecular species (CII, CO, 13CO, CH, CH+) and single pointedobservations of OH+ to trace the kinematics of the different phasesof MonR2.The understanding of the dynamics andenergetics of UCHII regions is key to study the feedback process ofnewly formed massive stars in their native molecular cloud, andtherefore the evolution of giant molecular clouds. In extragalacticresearch, these energetic environments could dominate the physical andchemical conditions in evolved starbursts like M82 and in the mostdistant galaxies. |
| Publication |
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| Instrument | HIFI_HifiPoint_dbs, HIFI_HifiMapping_load-raster, HIFI_HifiMapping_fly |
| Temporal Coverage | 2012-09-06T17:34:07Z/2013-03-29T02:16:21Z |
| 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 | 2013-09-28T23:17:12Z |
| Keywords | Herschel, HSC, submillimetre, far-infrared, HIFI, PACS, SPIRE |
| Publisher And Registrant | European Space Agency |
| Credit Guidelines | European Space Agency, pilleri et al., 2013, 'Dynamics of the ultracompact HII region Monoceros R2: solving the lifetime paradox of young massive star forming region', SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-iis2qyc |