High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter.

Details High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter. High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter.

Publishing date

Jan 1995

URL

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995phdt........13t&link_type=abstract

Journals

Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, BERKELEY, 1995.Source: Dissertation Abstracts International, Volume: 57-03, Section: B

Science

Other

Type

Scientific paper

Abstract

The Galactic anticenter is home to a wealth of features covering a wide range of forbidden velocities. The Anticenter shell (ACS) and the Anticenter chain high-velocity clouds (ACHVCs) are the most prominent H scI features. When the emission from H scI at permitted velocities is removed, the ACS ceases to maintain its shell-like morphology. Instead, it appears to be composed of two separate filaments elongated parallel to the Galactic plane. Interior to the ACS are a multitude of similarly oriented intermediate-velocity filaments (IVFs). Their appearance is similar to lines of constant longitude on the surface of a sphere. The spatial and kinematic data for all the filaments are modeled, and no robust signature of expansion is found. The ACS and IVFs are instead modeled as the remnants of oblique high-velocity cloud (HVC) collisions with the Galactic disk. This model links the presence of the ACHVCs with the other anomalous-velocity components. High-resolution H scI observations support the impact interpretation for the ACS, and they are used extensively to show that Cohen's stream, which lies at the tail end of the ACHVCs, is the remnant of a collision between HVC 168-43-280 and a low-velocity cloud. A simple mass and momentum conserving simulation demonstrates the elegance of this model. The velocity distribution in the simulated remnant is broader than observed, and some form of damping is required. The redistribution of momentum by the enhanced magnetic field in the compressed, postshock gas is the most promising damping mechanism. The distribution of column densities versus centroid velocities in Cohen's stream is asymmetric and is found to be a natural consequence of the different sixes of the colliding clouds. An optical survey for high-velocity interstellar absorption towards the ACS and ACHVCs resulted in no detections. The use of the high-resolution (3^' beam width) H scI maps provides for a more accurate interpretation of the nondetections. The possibility that the line of sight to the background star passed through a small-scale deficiency in the HVC is ruled out. Barring peculiar abundances for the absorbing species, the ACS is at least 950 pc, and the ACHVCs are at least 650 pc from the Sun.

Affiliated with

Also associated with

No associations

Rating

High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter. 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 High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-Velocity Clouds and Large-Scale Structure Towards the Galactic Anticenter. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-837451