Arecibo imaging of compact high-velocity clouds

Details Arecibo imaging of compact high-velocity clouds Arecibo imaging of compact high-velocity clouds

2001-02-06

arxiv.org/abs/astro-ph/0102085v1

Astronomy and Astrophysics

Astrophysics

29 pages, 16 degraded (sigh...) figures, accepted for publication in A&A

Scientific paper

10.1051/0004-6361:20010162

Ten isolated compact high-velocity clouds (CHVCs) of the type cataloged by Braun & Burton (1999) have been imaged with the Arecibo telescope and were found to have a nested core/halo morphology. We argue that a combination of high-resolution filled-aperture and synthesis data is crucial to determining the intrinsic properties of the CHVCs. We identify the halos as Warm Neutral Medium surrounding one or more cores in the Cool Neutral Medium phase. These halos are clearly detected and resolved by the Arecibo filled-aperture imaging, which reaches a limiting sensitivity (1 sigma) of N_H about 2x10^17 cm^-2 over the typical 70 km/s linewidth at zero intensity. The FWHM linewidth of the halo gas is found to be 25 km/s, consistent with a WNM thermal broadening within 10^4 K gas. Substantial asymmetries are found at high N_H (>10^18.5 cm^-2) levels in 60% of our sample. A high degree of reflection-symmetry is found at low N_H (<10^18.5 cm^-2) in all sources studied at these levels. The column-density profiles of the envelopes are described well by the sky-plane projection of a spherical exponential in atomic volume density, which allows estimating the characteristic central halo column density, N_H(0) = 4.1+/-3.2x10^19 cm^-2, and characteristic exponential scale-length, h_B=420+/-90 arcsec. For plausible values of the thermal pressure at the CNM/WNM interface, these edge profiles allow distance estimates to be made for the individual CHVCs studied here which range between 150 and 850 kpc. (abridged)

Affiliated with

Also associated with

No associations

Rating

Arecibo imaging of compact high-velocity clouds does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Arecibo imaging of compact high-velocity clouds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arecibo imaging of compact high-velocity clouds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-491842