CORINOS. III. Outflow Shocked Regions of the Low-mass Protostellar Source IRAS 15398-3359 with JWST and ALMA

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Main Authors: Okoda, Yuki, Yang, Yao-Lun, Evans II, Neal J., Kim, Jaeyeong, Jin, Mihwa, Garrod, Robin T., Francis, Logan, Johnstone, Doug, Ceccarelli, Cecilia, Codella, Claudio, Chandler, Claire J., Yamamoto, Satoshi, Sakai, Nami
Format: Preprint
Published: 2025
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author Okoda, Yuki
Yang, Yao-Lun
Evans II, Neal J.
Kim, Jaeyeong
Jin, Mihwa
Garrod, Robin T.
Francis, Logan
Johnstone, Doug
Ceccarelli, Cecilia
Codella, Claudio
Chandler, Claire J.
Yamamoto, Satoshi
Sakai, Nami
author_facet Okoda, Yuki
Yang, Yao-Lun
Evans II, Neal J.
Kim, Jaeyeong
Jin, Mihwa
Garrod, Robin T.
Francis, Logan
Johnstone, Doug
Ceccarelli, Cecilia
Codella, Claudio
Chandler, Claire J.
Yamamoto, Satoshi
Sakai, Nami
contents While molecular outflows have been studied in details with radio interferometry, observations of the hotter gas in protostellar outflows at a comparable physical scale is often challenging. Combined with ALMA, JWST allows us to investigate the cold and hot gas with unprecedented spatial resolution and sensitivity. We present a detailed comparison between the gas distributions probed with ALMA and JWST in the primary outflow of IRAS 15398$-$3359. At 2000 au scale, the southwestern outflow shows four shell structures in 5--10 micron continuum, whereas the submillimeter H$_2$CO emission traces two of the four shells closest to the protostar. Submillimeter emission from CS, CCH, c-C$_3$H$_2$, and CH$_3$OH shows the same two shells, and the $^{12}$CO emission covers most of the outflow region. SO and SiO only trace a condensation at the edge of the shell closest to the protostar. None of these lines observed with ALMA show the outermost shell. At 500 au scale, we find hot H$_2$ gas inside the outflow cavity with JWST. The derived temperature of H$_2$ is 1147$\pm$198 K within a 0\farcs5 aperture at the protostar. The foreground mass column density of dust is (1.4--2.0)$\times$10$^{-3}$ g$\cdot$cm$^{-2}$ (A$_{\rm v}$ = 47--66 mag) in the outflow, using the dust model from Weingartner & Draine (2001). We also find an 8$^{\circ}$ difference between the directions toward the [Fe II] knot and the outermost shell in the MIRI image, which may be interpreted as the precession of the [Fe II] jet. The dynamical timescale of the [Fe II] knot is 10 yrs, suggesting a current event.
format Preprint
id arxiv_https___arxiv_org_abs_2503_03050
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CORINOS. III. Outflow Shocked Regions of the Low-mass Protostellar Source IRAS 15398-3359 with JWST and ALMA
Okoda, Yuki
Yang, Yao-Lun
Evans II, Neal J.
Kim, Jaeyeong
Jin, Mihwa
Garrod, Robin T.
Francis, Logan
Johnstone, Doug
Ceccarelli, Cecilia
Codella, Claudio
Chandler, Claire J.
Yamamoto, Satoshi
Sakai, Nami
Solar and Stellar Astrophysics
Astrophysics of Galaxies
While molecular outflows have been studied in details with radio interferometry, observations of the hotter gas in protostellar outflows at a comparable physical scale is often challenging. Combined with ALMA, JWST allows us to investigate the cold and hot gas with unprecedented spatial resolution and sensitivity. We present a detailed comparison between the gas distributions probed with ALMA and JWST in the primary outflow of IRAS 15398$-$3359. At 2000 au scale, the southwestern outflow shows four shell structures in 5--10 micron continuum, whereas the submillimeter H$_2$CO emission traces two of the four shells closest to the protostar. Submillimeter emission from CS, CCH, c-C$_3$H$_2$, and CH$_3$OH shows the same two shells, and the $^{12}$CO emission covers most of the outflow region. SO and SiO only trace a condensation at the edge of the shell closest to the protostar. None of these lines observed with ALMA show the outermost shell. At 500 au scale, we find hot H$_2$ gas inside the outflow cavity with JWST. The derived temperature of H$_2$ is 1147$\pm$198 K within a 0\farcs5 aperture at the protostar. The foreground mass column density of dust is (1.4--2.0)$\times$10$^{-3}$ g$\cdot$cm$^{-2}$ (A$_{\rm v}$ = 47--66 mag) in the outflow, using the dust model from Weingartner & Draine (2001). We also find an 8$^{\circ}$ difference between the directions toward the [Fe II] knot and the outermost shell in the MIRI image, which may be interpreted as the precession of the [Fe II] jet. The dynamical timescale of the [Fe II] knot is 10 yrs, suggesting a current event.
title CORINOS. III. Outflow Shocked Regions of the Low-mass Protostellar Source IRAS 15398-3359 with JWST and ALMA
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2503.03050