A dataset provided by the European Space Agency

Name OT2_rvisser_2
Title Hot water in hot cores


DOI https://doi.org/10.5270/esa-vuvydbz
Author visser, r.
Description As matter flows from the ice-cold envelope onto a forming protostar, it heats up from temperatures of 10 K to more than 100 K. The region where the temperature exceeds 100 K (the hot core or hot corino) is where the molecular envelope connects with both the seedling circumstellar disk and the bipolar outflow. As the envelope contracts from larger scales, a lot of material passes through the hot core before accreting onto the disk. The hot core is therefore a crucial step in establishing the physical and chemical properties of planetary building blocks. However, little is yet known about hot cores. How large and how massive are they? How hot are they? Are they exposed to strong UV or X-ray fluxes? We propose the rotationally excited 3(12)-3(03) line of H2-18O at 1095.6 GHz (E_up = 249 K) as a novel probe into the properties of hot cores. This line was detected as a narrow emission feature (FWHM virgul4 km-s) in a deep integration (5 hr) in the Class 0 protostar NGC1333 IRAS2A. Comparing the line intensity to radiative transfer models, we find a tentative H2-16O hot core abundance of 4x10^-6. This is a factor of 50 lower than one would expect from simple evaporation of water ice above 100 K. Why is the hot core of IRAS2A so much drier than expected? Is most of the water destroyed by UV photons and-or X-rays? We propose to measure the water abundance in the hot cores of a sample of five additional Class 0 and I protostars by obtaining deep integrations of the 3(12)-3(03) lines of H2-16O and H2-18O. This mini-survey will reveal whether NGC1333 IRAS2A is unique in having a dry hot core, or whether dry hot cores are a common feature of low-mass embedded protostars. If they are a common feature, it means they are a more hostile environment than previously thought, with high fluxes of destructive UV photons and X-rays.
Publication Observational evidence for dissociative shocks in the inner 100 AU of low-mass protostars using Herschel-HIFI . Kristensen L. E. et al. . Astronomy & Astrophysics, Volume 557, id.A23, 13 pp. . 557 . 10.1051/0004-6361/201321619 . 2013A&A...557A..23K ,
High-J CO survey of low-mass protostars observed with Herschel-HIFI . Yıldız U. A. et al. . Astronomy & Astrophysics, Volume 556, id.A89, 46 pp. . 556 . 10.1051/0004-6361/201220849 . 2013A&A...556A..89Y ,
Water in star-forming regions with Herschel (WISH). V. The physical conditions in low-mass protostellar outflows revealed by multi-transition water observations . Mottram J. C. et al. . Astronomy & Astrophysics, Volume 572, id.A21, 49 pp. . 572 . 10.1051/0004-6361/201424267 . 2014A&A...572A..21M ,
Herschel-HIFI observations of high-J CO and isotopologues in star-forming regions: from low to high mass . San José-García I. et al. . Astronomy & Astrophysics, Volume 553, id.A125, 29 pp. . 553 . 10.1051/0004-6361/201220472 . 2013A&A...553A.125S ,
Linking low- to high-mass young stellar objects with Herschel-HIFI observations of water . San José-García I. et al. . Astronomy & Astrophysics, Volume 585, id.A103, 30 pp. . 585 . 10.1051/0004-6361/201525708 . 2016A&A...585A.103S ,
Instrument HIFI_HifiPoint_dbs
Temporal Coverage 2012-08-02T03:06:35Z/2012-10-25T07:48:44Z
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 2013-04-25T03:51:50Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, 2013, OT2_rvisser_2, SPG v14.1.0. https://doi.org/10.5270/esa-vuvydbz