JOYS: The [D/H] abundance derived from protostellar outflows across the Galactic disk measured with JWST
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2025
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| author | Francis, L. van Dishoeck, E. F. Garatti, A. Caratti o van Gelder, M. L. Gieser, C. Beuther, H. Tychoniec, T. P. Ray L. Kavanagh, P. Nazari S. Reyes P. J. Klaassen, P. Güdel, M. Henning, T. |
| author_facet | Francis, L. van Dishoeck, E. F. Garatti, A. Caratti o van Gelder, M. L. Gieser, C. Beuther, H. Tychoniec, T. P. Ray L. Kavanagh, P. Nazari S. Reyes P. J. Klaassen, P. Güdel, M. Henning, T. |
| contents | The total deuterium abundance [D/H] in the universe is set by just two processes: the creation of deuterium in Big Bang Nucleosynthesis at an abundance of [D/H]$=2.58\pm0.13\times10^{-5}$, and its destruction within stellar interiors. Measurements of the total [D/H] abundance can potentially provide a probe of Galactic chemical evolution, however, most measurements of [D/H] are only sensitive to the gas-phase deuterium, and the amount of deuterium sequestered in carbonaceous dust grains is debated. With the launch of JWST, it is now possible to measure the gas-phase [D/H] at unprecedented sensitivity and distances through observation of mid-IR lines of H$_2$ and HD. We employ data from the JWST Observations of Young protoStars (JOYS) program to measure the gas-phase [D/H] abundance with a rotation diagram analysis towards 5 nearby low-mass and 5 distant high-mass protostellar outflows. The gas-phase [D/H] varies between low-mass sources by up to a factor of $\sim4$, despite these sources likely having formed in a region of the Galactic disk that would be expected to have nearly constant total [D/H]. Most measurements of gas-phase [D/H] from our work or previous studies produce [D/H] $\lesssim 1.0\times10^{-5}$, a factor of $2-4$ lower than found from local UV absorption lines and as expected from Galactic chemical evolution models. The variations in [D/H] between our low-mass sources and the low [D/H] with respect to Galactic chemical evolution models suggest that our observations are not sensitive to the total [D/H]. Significant depletion of deuterium onto carbonaceous dust grains is a possible explanation, and tentative evidence of enhanced [D/H] towards shock positions with higher gas-phase Fe abundance is seen in the HH 211 outflow. Deeper observations of HD and H$_2$ in shocked environments and modelling of dust-grain destruction are warranted to test for the effects of depletion. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_02085 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | JOYS: The [D/H] abundance derived from protostellar outflows across the Galactic disk measured with JWST Francis, L. van Dishoeck, E. F. Garatti, A. Caratti o van Gelder, M. L. Gieser, C. Beuther, H. Tychoniec, T. P. Ray L. Kavanagh, P. Nazari S. Reyes P. J. Klaassen, P. Güdel, M. Henning, T. Astrophysics of Galaxies Solar and Stellar Astrophysics The total deuterium abundance [D/H] in the universe is set by just two processes: the creation of deuterium in Big Bang Nucleosynthesis at an abundance of [D/H]$=2.58\pm0.13\times10^{-5}$, and its destruction within stellar interiors. Measurements of the total [D/H] abundance can potentially provide a probe of Galactic chemical evolution, however, most measurements of [D/H] are only sensitive to the gas-phase deuterium, and the amount of deuterium sequestered in carbonaceous dust grains is debated. With the launch of JWST, it is now possible to measure the gas-phase [D/H] at unprecedented sensitivity and distances through observation of mid-IR lines of H$_2$ and HD. We employ data from the JWST Observations of Young protoStars (JOYS) program to measure the gas-phase [D/H] abundance with a rotation diagram analysis towards 5 nearby low-mass and 5 distant high-mass protostellar outflows. The gas-phase [D/H] varies between low-mass sources by up to a factor of $\sim4$, despite these sources likely having formed in a region of the Galactic disk that would be expected to have nearly constant total [D/H]. Most measurements of gas-phase [D/H] from our work or previous studies produce [D/H] $\lesssim 1.0\times10^{-5}$, a factor of $2-4$ lower than found from local UV absorption lines and as expected from Galactic chemical evolution models. The variations in [D/H] between our low-mass sources and the low [D/H] with respect to Galactic chemical evolution models suggest that our observations are not sensitive to the total [D/H]. Significant depletion of deuterium onto carbonaceous dust grains is a possible explanation, and tentative evidence of enhanced [D/H] towards shock positions with higher gas-phase Fe abundance is seen in the HH 211 outflow. Deeper observations of HD and H$_2$ in shocked environments and modelling of dust-grain destruction are warranted to test for the effects of depletion. |
| title | JOYS: The [D/H] abundance derived from protostellar outflows across the Galactic disk measured with JWST |
| topic | Astrophysics of Galaxies Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2501.02085 |