English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Recent measurements carried out at comet 67P/C-G with the ${\it Rosetta}$probe revealed that molecular oxygen, O$_2$, is the fourth most abundantmolecule in comets. Models show that O$_2$ is likely of primordial nature,coming from the interstellar cloud from which our Solar System was formed.However, gaseous O$_2$ is an elusive molecule in the interstellar medium withonly one detection towards quiescent molecular clouds, in the $\rho$ Oph Acore. We perform a deep search for molecular oxygen, through the $2_1 - 0_1$rotational transition at 234 GHz of its $^{16}$O$^{18}$O isotopologue, towardsthe warm compact gas surrounding the nearby Class 0 protostar IRAS 16293--2422B with the ALMA interferometer. The targeted $^{16}$O$^{18}$O transition issurrounded by two brighter transitions at $\pm 1$ km s$^{-1}$ relative to theexpected $^{16}$O$^{18}$O transition frequency. After subtraction of these twotransitions, residual emission at a 3$\sigma$ level remains, but with avelocity offset of $0.3 - 0.5$ km s$^{-1}$ relative to the source velocity,rendering the detection "tentative". We derive the O$_2$ column density for twoexcitation temperatures $T_{\rm ex}$ of 125 and 300 K, as indicated by othermolecules, in order to compare the O$_2$ abundance between IRAS16293 and comet67P/C-G. Assuming that $^{16}$O$^{18}$O is not detected and using methanolCH$_3$OH as a reference species, we obtain a [O$_2$]/[CH$_3$OH] abundance ratiolower than $2-5$, depending on the assumed $T_{\rm ex}$, a three to four timeslower abundance than the [O$_2$]/[CH$_3$OH] ratio of $5-15$ found in comet67P/C-G. Such a low O$_2$ abundance could be explained by the lower temperatureof the dense cloud precursor of IRAS16293 with respect to the one at the originof our Solar System that prevented an efficient formation of O$_2$ ininterstellar ices.

Linking interstellar and cometary O$_2$: a deep search for $^{16}$O$^{18}$O in the solar-type protostar IRAS 16293--2422