The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project
Abstract
The Orion nebula is the nearest site of ongoing and recent high-mass star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an expanding shell that matches the EON contours delineated by recent observations of ionized carbon ([CII]) line emission. However, our combination of single-dish and interferometric HI observations suggests 100 solar masses of material for the front hemisphere of the shell, which is lower by roughly a factor of ten than the mass inferred from [CII] observations. This discrepancy suggests that the mass of the nearest wind-blown bubble has been overestimated, although we do not rule out the possibility that a significant amount of molecular hydrogen (H 2 ) in the shell may account for part of the difference. Our extended 21 cm line maps also reveal uncharted structures in and around the EON. They include a probable secondary bubble and a linear protrusion extending roughly four parsecs from the shell boundary. Our results illustrate the potential of HI interferometric observations to elucidate key aspects of the multiphase structure of star-forming regions and their connection to their surroundings.
Versions
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BibTeX
@article{soler2026neutral,
title = {{The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project}},
author = {J D Soler and H Beuther and S C O Glover and R S Klessen and J Ott and M Rugel and J W Teh and S E Clark and P Goldsmith and A Hacar and A Socci and M Heyer and M-Y Lee and C E Murray and D Seifried and S Walch and B Godard and M-A Miville-Deschênes},
journal = {Astronomy \& Astrophysics - A\&A},
year = {2026},
month = jul,
doi = {10.1051/0004-6361/202659272},
eprint = {2609.02658},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05800694v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project
AU - J D Soler
AU - H Beuther
AU - S C O Glover
AU - R S Klessen
AU - J Ott
AU - M Rugel
AU - J W Teh
AU - S E Clark
AU - P Goldsmith
AU - A Hacar
AU - A Socci
AU - M Heyer
AU - M-Y Lee
AU - C E Murray
AU - D Seifried
AU - S Walch
AU - B Godard
AU - M-A Miville-Deschênes
PY - 2026
DA - 2026/07/08
JO - Astronomy & Astrophysics - A&A
DO - 10.1051/0004-6361/202659272
UR - https://hal.science/hal-05800694v1
AB - The Orion nebula is the nearest site of ongoing and recent high-mass star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an expanding shell that matches the EON contours delineated by recent observations of ionized carbon ([CII]) line emission. However, our combination of single-dish and interferometric HI observations suggests 100 solar masses of material for the front hemisphere of the shell, which is lower by roughly a factor of ten than the mass inferred from [CII] observations. This discrepancy suggests that the mass of the nearest wind-blown bubble has been overestimated, although we do not rule out the possibility that a significant amount of molecular hydrogen (H 2 ) in the shell may account for part of the difference. Our extended 21 cm line maps also reveal uncharted structures in and around the EON. They include a probable secondary bubble and a linear protrusion extending roughly four parsecs from the shell boundary. Our results illustrate the potential of HI interferometric observations to elucidate key aspects of the multiphase structure of star-forming regions and their connection to their surroundings.
SN - 0004-6361
SN - 1432-0746
ER -