The nature of Cloud-9: a compact core embedded in a diffuse envelope

Clicks: 1
ID: 320498
2026
Free PDF
Article Quality & Performance Metrics
Overall Quality
Not rated
Combines reader engagement with the AI quality analysis. This article has not been analysed, so there is no overall score — reader engagement is measured and shown alongside.
AI Quality Assessment
Not analyzed
Readership in this journal

Ranked #790 of 897 articles by views in monthly notices of the royal astronomical society

Most read Least read

Bar heights use a square-root scale. Only the 120 most-read articles are drawn; the journal has 897 in total.

Mint this article as an NFT
Not yet minted

Create a permanent, verifiable on-chain record of this article on the Scimatic Network. The NFT is held in your Journament account, and you can withdraw it to your own wallet at any time.

5 SUSD one-off · no wallet required
Sign in to mint
Abstract
Abstract We present new H i observations of Cloud-9 with the Five-hundred-meter Aperture Spherical Telescope (FAST), measuring total flux of 0.35 ± 0.03 Jy km s−1. Combined with Very Large Array (VLA) data, the H i shows a two-component structure: a compact, kinematically quiescent core and an extended envelope. The outer component exhibits a coherent velocity gradient of ~25 km s−1 across ~7 kpc. The position–velocity structure does not support rotation; instead, the gradient is consistent with ordered large-scale motion, induced by environmental interaction with M94. The coexistence of a compact, kinematically quiescent core and an extended structured envelope is difficult to reconcile with a unbound or purely gaseous system. While the extended component is more naturally interpreted as environmentally shaped gas, the compact core suggests gravitational confinement beyond that provided by the observed baryonic content, without requiring strict long-term dynamical equilibrium. Deep optical limits further rule out a significant stellar component. Taken together, our results indicate that Cloud-9 is most naturally interpreted as a dark matter-dominated system undergoing environmental interaction. The observed morphology and kinematics are consistent with a stripped RELHIC scenario, in which a compact gas-rich core is embedded within an extended envelope shaped by ram-pressure interaction with the circumgalactic medium of M94.
Reference Key
openalex_W7167919080 Use this key to autocite in the manuscript while using SciMatic Manuscript Manager or Thesis Manager
Authors Ruilei Zhou, Ming Zhu, Chuan-Peng Zhang, J R Xu
Journal monthly notices of the royal astronomical society
Year 2026
DOI
10.1093/mnras/stag1293
URL
https://doi.org/10.1093/mnras/stag1293
Keywords Keywords not found

Citations

No citations found. To add a citation, contact the admin at info@scimatic.org

Comments

No comments yet. Be the first to comment on this article.