Deep HI Mapping of Stephan's Quintet and Its Neighborhood
Cheng Cheng, Cong Kevin Xu, P. N. Appleton, P.-A. Duc, N.-Y. Tang,, Y.S. Dai, J.-S. Huang, U. Lisenfeld, F. Renaud, Chuan He, and Hai-Cheng Feng

TL;DR
This study uses FAST to map atomic hydrogen in Stephan's Quintet, revealing more HI than previously known and suggesting that missing HI may be in diffuse gas rather than ionized gas.
Contribution
First deep HI mapping of Stephan's Quintet with FAST, detecting significant HI mass and revealing that the group is not HI deficient, challenging prior assumptions.
Findings
Total HI mass of SQ is significantly higher than previous estimates.
Detected HI in velocity ranges previously undetected due to sensitivity limits.
Suggests missing HI in compact groups may reside in diffuse neutral gas.
Abstract
We carried out deep mapping observations of the atomic hydrogen (HI) 21 cm line emission in a field centered on the famous galaxy group Stephan's Quintet (SQ), using the Five-hundred-meter Aperture Spherical Telescope (FAST) equipped with the 19-Beam Receiver. The final data cube reaches an HI column density sensitivity of cm per 20 km s channel with an angular resolution of . The discovery of a large diffuse feature of the HI emission in the outskirt of the intragroup medium of SQ was reported in a previous paper (Xu et al. 2022). Here we present a new study of the total HI emission of SQ and the detection of several neighboring galaxies, exploiting the high sensitivity and the large sky coverage of the FAST observations. A total HI mass of is found for SQ, which is significantly…
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Taxonomy
TopicsGalaxies: Formation, Evolution, Phenomena · Astrophysics and Cosmic Phenomena · Astronomy and Astrophysical Research
