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Title: Deep Search for Molecular Oxygen in TW Hya
Abstract The dominant form of oxygen in cold molecular clouds is gas-phase carbon monoxide (CO) and ice-phase water (H2O). Yet, in planet-forming disks around young stars, gas-phase CO and H2O are less abundant relative to their interstellar medium values, and no other major oxygen-carrying molecules have been detected. Some astrochemical models predict that gas-phase molecular oxygen (O2) should be a major carrier of volatile oxygen in disks. We report a deep search for emission from the isotopologue16O18O (NJ= 21− 01line at 233.946 GHz) in the nearby protoplanetary disk around TW Hya. We used imaging techniques and matched filtering to search for weak emission but do not detect16O18O. Based on our results, we calculate upper limits on the gas-phase O2abundance in TW Hya of (6.4–70) × 10−7relative to H, which is 2–3 orders of magnitude below solar oxygen abundance. We conclude that gas-phase O2is not a major oxygen carrier in TW Hya. Two other potential oxygen-carrying molecules, SO and SO2, were covered in our observations, which we also do not detect. Additionally, we report a serendipitous detection of the C15NNJ= 25/2− 13/2hyperfine transitions,F= 3 − 2 andF= 2 − 1, at 219.9 GHz, which we found via matched filtering and confirm through imaging.  more » « less
Award ID(s):
2205698
PAR ID:
10535234
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
IOPP
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
956
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
135
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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