A dataset provided by the European Space Agency

Name OT1_mhogerhe_1
Title Deep HIFI searches for cold water vapor in protoplanetary disks


DOI https://doi.org/10.5270/esa-vsw96sn
Author European Space Agency
Description Water vapor inside planet-forming disks is expected to show large
variations. In the warm (virgul200 K) inner few AU of the disk all oxygen
is locked up in water vapor. In the colder outer region water quickly
freezes out onto dust grains. However, efficient photodesorption by
stellar ultraviolet radiation will return an appreciable fraction back
into the gas phase in the upper disk layers. This coupled water
ice/vapor system explains the Spitzer observations of warm water in
several disks, and predicts the presence of cold water vapor in the
outer disk.
Through the .Water in Star Forming Regions. (WISH) Key Program, we
have recently clearly detected the groundstate line of cold water
vapor to TW Hya and very tentatively detected it to DM Tau. Both lines
are factors 10-50 weaker than expected. We hypothesize that up to 99%
of icy grains have settled to the disk.s midplane thus .freeze drying.
the upper disk layers.
The WISH data do not go deep enough to probe cold water vapor content
now that we know that the outer disk is freeze-dried. The only clear
detection is TW Hya, which has a distance of only 51 pc. At more
typical distances of 100-140 pc, line strengths are lower by factors
5-8, beyond the sensitivity of WISH.
We propose much deeper HIFI observations of the H2O 110-101 line at
557 GHz of four targets: DM Tau (to confirm or reject WISH.s .very
tentative. detection), and HD100546, HD163296, and AA Tau. These disks
are, after TW Hya, the closest and largest disks that offer the best
chances of detection. Because of the sensitivity of H2O 110-101 to
cold water vapor in the outer disk, our observations probe as-of-yet
unexplored grain settling in the outer disk and enrichment of the
midplane with icy grains. This can boost planet formation, since icy
grains coagulate more easily.
Our proposal also contains a small request for v...elocity-resolved CO
10-9 observations with HIFI to study warm (virgul200 K) gas in these four
disks, and investigate if preferential settling of icy grains also
affects CO.
Instrument HIFI_HifiPoint_dbs
Temporal Coverage 2011-12-23T15:57:04Z/2012-09-06T16:35:47Z
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 2013-03-06T11:15:02Z
Publisher And Registrant European Space Agency
Credit Guidelines European Space Agency, 2013, Deep Hifi Searches For Cold Water Vapor In Protoplanetary Disks, SPG v14.1.0, European Space Agency, https://doi.org/10.5270/esa-vsw96sn