The Silk Nebula: A Newly Discovered Giant [O iii ] Emission Filament
9 affiliations
- 1Chinese Academy of Sciences
- 2University of Chinese Academy of Sciences
- 3AEROSPACE KNOWLEDGE PRESS
- 4Nanjing University
- 5Light Speed Vision Beijing Co.LTD (QHYCCD)
- 6China West Normal University
- 7he Chinese University of Hong Kong
- 8Xingming Observatory
- 9Lijiang Gemini Observatory
Abstract
We report [O iii ] narrowband imaging of an extremely large-scale nebula, the Silk Nebula, discovered by the Super Wide-Field [O iii] Narrow-band Survey (SWONS), together with multifiber medium-resolution spectroscopic data covering the H α , [N ii ], [S ii ], and [O iii ] emission lines, acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) as part of the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N). Based on 2684 high-quality spectra, we measured its physical parameters, including relative line intensities, radial velocities, and full widths at half-maximum. The [S ii ]/H α ratio of the nebula significantly exceeds the shock-excitation threshold of 0.4. Its location in BPT diagnostic diagrams and spatial morphology of [O iii ] both support the optical emission is dominated by shock-heated gas. The oxygen abundance is near solar and spatially uniform, consistent with a shock propagating into the ambient interstellar medium. Because [O iii ] is the only emission line that clearly traces the nebular morphology, we base our distance estimate exclusively on the [O iii ] kinematics, obtaining a fiducial distance of ∼160 pc. At this distance, the nebula has a physical extent of ∼28 pc along the north–south direction. We suggest that the Silk Nebula is a large [O iii ] filament possibly associated with a supernova remnant, although a diffuse-ionized-gas (DIG) or ionized-bubble origin cannot be ruled out with the present data, and one of the largest angular-scale [O iii ] emission structures documented to date. Future deep X-ray observations and shock-modeling efforts are required to firmly establish its nature.
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BibTeX
@article{wu2026silk,
title = {{The Silk Nebula: A Newly Discovered Giant [O iii ] Emission Filament}},
author = {Yi-Fei Wu and Song-Yu Jia and Chao-Jian Wu and Chao Zhang and Li-Yue Zhang and Shu Wang and Juan-Juan Ren and Quzhen Dongyang and Hong-Yun Qiu and Zhi-Hong He and Jichen Zhang and Guo-You Sun and Wei-Guo Zhang and Jian-Jun Chen and Hong-Liang Yan and Xiang-Song Fang and Hong Wu},
journal = {The Astronomical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-3881/aeb11c},
url = {https://iopscience.iop.org/article/10.3847/1538-3881/aeb11c},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The Silk Nebula: A Newly Discovered Giant [O iii ] Emission Filament
AU - Yi-Fei Wu
AU - Song-Yu Jia
AU - Chao-Jian Wu
AU - Chao Zhang
AU - Li-Yue Zhang
AU - Shu Wang
AU - Juan-Juan Ren
AU - Quzhen Dongyang
AU - Hong-Yun Qiu
AU - Zhi-Hong He
AU - Jichen Zhang
AU - Guo-You Sun
AU - Wei-Guo Zhang
AU - Jian-Jun Chen
AU - Hong-Liang Yan
AU - Xiang-Song Fang
AU - Hong Wu
PY - 2026
DA - 2026/11/04
JO - The Astronomical Journal
DO - 10.3847/1538-3881/aeb11c
UR - https://iopscience.iop.org/article/10.3847/1538-3881/aeb11c
AB - We report [O iii ] narrowband imaging of an extremely large-scale nebula, the Silk Nebula, discovered by the Super Wide-Field [O iii] Narrow-band Survey (SWONS), together with multifiber medium-resolution spectroscopic data covering the H α , [N ii ], [S ii ], and [O iii ] emission lines, acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) as part of the Medium-Resolution Spectroscopic Survey of Nebulae (MRS-N). Based on 2684 high-quality spectra, we measured its physical parameters, including relative line intensities, radial velocities, and full widths at half-maximum. The [S ii ]/H α ratio of the nebula significantly exceeds the shock-excitation threshold of 0.4. Its location in BPT diagnostic diagrams and spatial morphology of [O iii ] both support the optical emission is dominated by shock-heated gas. The oxygen abundance is near solar and spatially uniform, consistent with a shock propagating into the ambient interstellar medium. Because [O iii ] is the only emission line that clearly traces the nebular morphology, we base our distance estimate exclusively on the [O iii ] kinematics, obtaining a fiducial distance of ∼160 pc. At this distance, the nebula has a physical extent of ∼28 pc along the north–south direction. We suggest that the Silk Nebula is a large [O iii ] filament possibly associated with a supernova remnant, although a diffuse-ionized-gas (DIG) or ionized-bubble origin cannot be ruled out with the present data, and one of the largest angular-scale [O iii ] emission structures documented to date. Future deep X-ray observations and shock-modeling efforts are required to firmly establish its nature.
SN - 0004-6256
SN - 1538-3881
ER -