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BOLIDE FRAGMENTATION PROCESSES : SINGLE-BODY MODELING VERSUS THE CATASTROPHIC FRAGMENTATION LIMIT.

Description: The catastrophic 'pancake' fragmentation process, proposed as being generally applicable to very large meteoroid entry in the early 1990's by a number of workers, has been carefully examined. In this effort, the transition from the traditional single-body dynamics and energetics model to a catastrophic 'pancake' fragmentation process has been delineated. The key parameters are the {mu} parameter originally proposed by Levin and the fragmentation scale height, Hf, which we have derived from {mu}… more
Date: January 1, 2001
Creator: ReVelle, D. O. (Douglas O.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

CALCULATIONS OF SHAPE CHANGE AND FRAGMENTATION PARAMETERS USING VERY PRECISE BOLIDE DATA.

Description: Using the theoretical formalism of ReVelle (2001d), we have analyzed 22 European (EN) and US Prairie Network fireballs (PN) with the most precise trajectory information available for shape change and fragmentation effects. For 14 bolides the shape change parameter, {mu}, was always > 0 and for the other 8 cases there were instances of {mu} < 0, but with large oscillations in its sign with height or time. When the shape change parameter, {mu}, was < 0, the fragmentation scale height was… more
Date: January 1, 2001
Creator: ReVelle, D. O. (Douglas O.) & Ceplecha, Zdeněk
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The milky way tomography with sdss

Description: Using the photometric parallax method, we estimate the distances to {approx}48 million stars detected by the Sloan Digital Sky Survey (SDSS), and map their three-dimensional number density distribution in the Galaxy. The currently available data sample the distance range from 100 pc to 15 kpc and cover 6,500 deg{sup 2} of sky, mostly at high galactic latitudes (|b| > 25). These stellar number density maps allow an investigation of the Galactic structure without any a priori assumptions about… more
Date: October 1, 2005
Creator: Juric, Mario; Ivezic, Zeljko; Brooks, Alyson; Lupton, Robert H.; Schlegel, David; Finkbeiner, Douglas et al.
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Partner: UNT Libraries Government Documents Department
open access

COMET SHOWERS ARE NOT INDUCED BY INTERSTELLAR CLOUDS

Description: Encounters with interstellar clouds (IC) have been proposed by Rampino and Stothers as a cause of quasi-periodic intense comet showers leading to earth impacts, in order to explain the periodicity in marine mass extinctions found by Raup and Sepkoski. The model was described further, criticized and defended. The debate has centered on the question of whether the scale height of the clouds is small enough (in comparison to the amplitude of the oscillation of the solar system about the plane of t… more
Date: November 1, 1985
Creator: Morris, Donald E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A New Catalog of Radio Compact H II Regions in the Milky Way

Description: We utilize new VLA Galactic plane catalogs at 5 and 1.4 GHz covering the first Galactic quadrant (350{sup o} {le} l {le} 42{sup o}, |b| {le} 0.4{sup o}) in conjunction with the MSX6C Galactic plane catalog to construct a large sample of ultra-compact H II regions. A radio catalog of this region was first published by Becker et al. (1994), but we have added new observations and re-reduced the data with significantly improved calibration and mosaicing procedures, resulting in a tripling of the nu… more
Date: November 2, 2004
Creator: Giveon, U.; Becker, R.; Hefland, D. & White, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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