Deep H I observations of the compact high-velocity cloud HVC125+41-207

Abstract

We present deep HI observations of the compact high-velocity cloud HVC125+41-207 using the 100-m Effelsberg telescope. Our goal was in particular to study the warm neutral medium (WNM) in detail. The Effelsberg data reveal a two phase core/halo structure - one component with a velocity width of FWHM approx 5 km/s (Westerbork data show FWHM approx 2 km/s, Braun & Burton 2000) and one with FWHM approx 18 km/s. The column density distribution of the warmer component is highly asymmetric and shows a head-tail structure. We performed a Gaussian decomposition of the cloud and found that 52% of the HI mass of the cloud is in the WNM. 24% of the WNM is located in the tail. The overall structure and the systematic variation of the observational parameters radial velocity, velocity dispersion and column density indicate that this cloud is currently interacting with the ambient medium. The Westerbork HI data of this HVC (Braun & Burton 2000) reveal an interesting dense condensation. Assuming that this condensation is virialized and in pressure equilibrium with the ambient medium, we derive a distance of 130 kpc for HVC125+41-207. Following these considerations, it is possible to constrain the parameters n_IGM < 7.8 10^-6 cm^-3 and T_IGM > 1.1 10^5 K of the intergalactic medium of the Local Group.

5 pages, 2 figures, LaTeX2e, accepted for publication in A&A Letters

Cited by in corpus (45)

• Highly-Ionized High-Velocity Gas in the Vicinity of the Galaxy
• Multi-Phase Galaxy Formation: High Velocity Clouds and the Missing Baryon Problem
• Science with ASKAP - the Australian Square Kilometre Array Pathfinder
• The Origin of the Magellanic Stream and Its Leading Arm
• Accretion of gas onto nearby spiral galaxies
• The Parkes HI Survey of the Magellanic System
• Complex C: A Low-Metallicity High-Velocity Cloud Plunging into the Milky Way
• The Fate of High-Velocity Clouds: Warm or Cold Cosmic Rain?
• Atomic Hydrogen Gas in Dark-Matter Minihalos and the Compact High Velocity Clouds
• The Effelsberg-Bonn HI Survey (EBHIS)
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• Westerbork HI observations of high-velocity clouds near M31 and M33
• Where are the high velocity clouds?
• The mode of gas accretion onto star-forming galaxies
• The small-scale structure of the Magellanic Stream
• An HI survey of six Local Group analogs: I. Survey description and the search for high-velocity clouds
• Detection of neutral hydrogen in early-type dwarf galaxies of the Sculptor Group
• High-resolution imaging of compact high-velocity clouds (II)
• Relics of structure formation: extra-planar gas and high-velocity clouds around the Andromeda Galaxy
• Effelsberg HI observations of compact high-velocity clouds
• The four leading arms of the Magellanic Cloud system
• Evaporation and condensation of spherical interstellar clouds. Self-consistent models with saturated heat conduction and cooling
• HI Observations of an Ultra-Compact High-Velocity Cloud
• High-resolution 21-cm observations of low-column density gas clumps in the Milky Way halo
• Physical properties of two compact high-velocity clouds possibly associated with the Leading Arm of the Magellanic System
• Searching for Stars in Compact High-Velocity Clouds. I First Results from VLT and 2MASS
• Mass, Morphing, Metallicities: The Evolution of Infalling High Velocity Clouds
• Physical effects on compact high-velocity clouds in the circumgalactic medium
• Identifying galaxy candidates in WSRT HI imaging of ultra-compact high velocity clouds
• X-Ray Searches for Emission from the WHIM in the Galactic Halo and the Intergalactic Medium
• Neutral hydrogen in galactic fountains
• Do High-Velocity Clouds trace the Dark Matter subhalo population?
• A High-Velocity Cloud Impact Forming a Supershell in the Milky Way
• Dust in a compact, cold, high-velocity cloud: A new approach to removing foreground emission
• Probing the Structure and Kinematics of the transition Layer between the Magellanic Stream and the Halo in HI
• HI observations of three compact high-velocity clouds around the Milky Way
• The Distance and Properties of Hydrogen Clouds in the Leading Arm of the Magellanic System
• Global properties of the HI high velocity sky, a statistical investigation based on the LAB survey
• The Nature and Origin of the Non-Void Lyman alpha Cloud Population
• Three-Dimensional Orientation of Compact High Velocity Clouds
• Tracing dense and diffuse neutral hydrogen in the halo of the Milky Way
• The Long Tails of the Pegasus-Pisces Arch Intermediate Velocity Cloud
• X-ray discovery of a dwarf-galaxy galaxy collision
• Resolving the formation of cold HI filaments in the high velocity cloud complex C
• The Baryonic Mass Estimates of the Milky Way Halo in the form of High Velocity Clouds