A dataset provided by the European Space Agency

Name OT2_ewirst01_1
Title Depletion Cores - the O2 Hideout?


DOI https://doi.org/10.5270/esa-4v9rolm
Author European Space Agency
Description Molecular oxygen has proven to be the most elusive molecule in the
interstellar medium. Despite the fact that it in theory forms easily in both
warm and cold dense gas, extensive searches with SWAS, Odin and Herschel
have only resulted in detections in two sources. In addition, upper limits in
various astronomical environments are at levels of 1000 times less abundant
than predicted by chemical models.

This situation requires either for atomic carbon to be abundant enough to
suppress the O2 by CO formation, or for atomic oxygen to accrete onto
grains and remain bound there.
However, the binding energies of atoms to grains are highly uncertain and
high abundances of OI in depleted gas have both been directly observed
and inferred from observations of other molecules. A possible explanation
is that OI is bound to grains by fixing (get hydrogenated to form ices) rather
than sticking (van der Waals bonding to the surface potential), which will
become less efficient in high density gas.

Based on this, our calculations show that molecular oxygen could be abundant in
dense cores of high CO depletion. To test this theory, we propose to search
a small sample of starless depletion cores for emission in the
low excitation O2 line at 487.249virgulGHz using Herschel HIFI.
Publication A Search for O2 in CO-depleted Molecular Cloud Cores with Herschel . Wirström Eva S. et al. . The Astrophysical Journal, Volume 830, Issue 2, article id. 102, 5 pp. (2016). . 830 . 10.3847\/0004-637X\/830\/2\/102 . 2016ApJ...830..102W ,
Instrument HIFI_HifiPoint_dbs
Temporal Coverage 2012-05-04T19:22:18Z/2012-09-29T11:26:37Z
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 2013-03-29T10:20:00Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, 2013, Depletion Cores - The O2 Hideoutquestionmark, SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-4v9rolm