Detection Of Phosphorus-bearing Molecules Towards A Solar-type Protostar


RADEX modeling results as a function of input gas density and temperature for an input PN column density of 1012 cm−2 . Left: recovered rotational temperatures, with contours marking the region consistent with the observed rotational temperatures of 6–10 K. Right: recovered column density as a fraction of the input column density, with contours reproduced from the left panel.

Phosphorus is a key ingredient in terrestrial biochemistry, but is rarely observed in the molecular ISM and therefore little is known about how it is inherited during the star and planet formation sequence.


We present observations of the phosphorus-bearing molecules PO and PN towards the Class I low-mass protostar B1-a using the IRAM 30m telescope, representing the second detection of phosphorus carriers in a Solar-type star forming region. The P/H abundance contained in PO and PN is ~10−10-10−9 depending on the assumed source size, accounting for just 0.05-0.5% of the solar phosphorus abundance and implying significant sequestration of phosphorus in refractory material.

Based on a comparison of the PO and PN line profiles with the shock tracers SiO, SO2, and CH3OH, the phosphorus molecule emission seems to originate from shocked gas and is likely associated with a protostellar outflow. We find a PO/PN column density ratio of ~1-3, which is consistent with the values measured in the shocked outflow of the low-mass protostar L1157, the massive star-forming regions W51 and W3(OH), and the galactic center GMC G+0.693-0.03. This narrow range of PO/PN ratios across sources with a range of environmental conditions is surprising, and likely encodes information on how phosphorus carriers are stored in grain mantles.

Jennifer B. Bergner, Karin I. Oberg, Salma Walker, Viviana V. Guzman, Thomas S. Rice, Edwin A. Bergin
(Submitted on 10 Oct 2019)
Comments: Accepted to ApJL
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:1910.04539 [astro-ph.SR] (or arXiv:1910.04539v1 [astro-ph.SR] for this version)
Submission history
From: Jennifer Bergner
[v1] Thu, 10 Oct 2019 13:18:09 UTC (323 KB)
https://arxiv.org/abs/1910.04539
Astrobiology, Astrochemistry

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