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Auteurs principaux: Nickerson, Sarah L., Rangwala, Naseem, Sung, Keeyoon, Huang, Xinchuan, Montiel, Edward J., DeWitt, Curtis, Gouellec, Valentin J. M. Le, Colgan, Sean W. J., Dittmann, Jason, Fonfría, Jose Pablo, Harper, Graham M., Kraemer, Kathleen E., Li, Jialu, Nixon, Conor A., Rashman, Maisie Frances, Sousa-Silva, Clara, Tielens, Alexander G. G. M., Vacca, William D.
Format: Preprint
Publié: 2025
Sujets:
Accès en ligne:https://arxiv.org/abs/2508.00059
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author Nickerson, Sarah L.
Rangwala, Naseem
Sung, Keeyoon
Huang, Xinchuan
Montiel, Edward J.
DeWitt, Curtis
Gouellec, Valentin J. M. Le
Colgan, Sean W. J.
Dittmann, Jason
Fonfría, Jose Pablo
Harper, Graham M.
Kraemer, Kathleen E.
Li, Jialu
Nixon, Conor A.
Rashman, Maisie Frances
Sousa-Silva, Clara
Tielens, Alexander G. G. M.
Vacca, William D.
author_facet Nickerson, Sarah L.
Rangwala, Naseem
Sung, Keeyoon
Huang, Xinchuan
Montiel, Edward J.
DeWitt, Curtis
Gouellec, Valentin J. M. Le
Colgan, Sean W. J.
Dittmann, Jason
Fonfría, Jose Pablo
Harper, Graham M.
Kraemer, Kathleen E.
Li, Jialu
Nixon, Conor A.
Rashman, Maisie Frances
Sousa-Silva, Clara
Tielens, Alexander G. G. M.
Vacca, William D.
contents We present the first astrophysical detection of methanol (CH3OH) in the torsional band near 25 um. Using high resolution mid-infrared (MIR) spectroscopy, we identified over seventy gas-phase CH3OH absorption lines between 20 and 28 um towards the massive protostar NGC 7538 IRS 1 with SOFIA/EXES. We derive a temperature of 180 K and a total column density of 2 x 10^17 cm-2, comparable to sub-mm measurements. Complementary analysis of acetylene (C2H2) absorption lines is also included. Both CH3OH and C2H2 reveal an unresolved second velocity component. These MIR absorption lines likely probe the molecular material in two edge-on disks, supporting the scenario that NGC 7538 IRS 1 consists of multiple protostars. We provide an updated line list for the torsional band of CH3OH, which was generated from lab work and model calculations. This discovery and the updated line list will enable the search for CH3OH in JWST/MIRI spectra.
format Preprint
id arxiv_https___arxiv_org_abs_2508_00059
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Discovery of 25 um Interstellar Methanol
Nickerson, Sarah L.
Rangwala, Naseem
Sung, Keeyoon
Huang, Xinchuan
Montiel, Edward J.
DeWitt, Curtis
Gouellec, Valentin J. M. Le
Colgan, Sean W. J.
Dittmann, Jason
Fonfría, Jose Pablo
Harper, Graham M.
Kraemer, Kathleen E.
Li, Jialu
Nixon, Conor A.
Rashman, Maisie Frances
Sousa-Silva, Clara
Tielens, Alexander G. G. M.
Vacca, William D.
Astrophysics of Galaxies
We present the first astrophysical detection of methanol (CH3OH) in the torsional band near 25 um. Using high resolution mid-infrared (MIR) spectroscopy, we identified over seventy gas-phase CH3OH absorption lines between 20 and 28 um towards the massive protostar NGC 7538 IRS 1 with SOFIA/EXES. We derive a temperature of 180 K and a total column density of 2 x 10^17 cm-2, comparable to sub-mm measurements. Complementary analysis of acetylene (C2H2) absorption lines is also included. Both CH3OH and C2H2 reveal an unresolved second velocity component. These MIR absorption lines likely probe the molecular material in two edge-on disks, supporting the scenario that NGC 7538 IRS 1 consists of multiple protostars. We provide an updated line list for the torsional band of CH3OH, which was generated from lab work and model calculations. This discovery and the updated line list will enable the search for CH3OH in JWST/MIRI spectra.
title The Discovery of 25 um Interstellar Methanol
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2508.00059