8,889 research outputs found
Controlled visibility device for an aircraft Patent
Controlled visibility device for simulating poor visibility conditions in training pilots in instrument landing and flight procedure
Summary of XB-70 airplane cockpit environmental data
Thermal, acoustical, and acceleration environments of XB-70 airplane crew compartment in airworthiness test
Are dwarf spheroidal galaxies dark matter dominated or remnants of disrupted larger satellite galaxies? -- A possible test
The failure of standard cosmolocical models in accounting for the statistics
of dwarf satellites and the rotation curve of gas-rich dwarf galaxies in detail
has led us to examine whether earlier non-equilibrium models of dwarf
spheroidal satellites without any dark matter should be reconsidered in more
detail. Such models can explain the high dispersion of the dwarf spheroids by
the projection of disrupted tidal debris. We show in the case of Milky Way
satellites, that these models predict a significant spread in the apparent
magnitude of horizontal branch stars which is correlated with sky position and
velocity. In particular, the models produce a strong correlation of radial
velocity with the long axis of the dwarf. Current data do not set strong enough
constraints on the models, but we suggest that photometric and spectroscopic
surveys of extra-tidal stars of nearby dwarf spheroids in the Milky Way and
Andromeda can falsify these models without dark matter.Comment: 7 pages, 5 figures, accepted for publication in Ap
Draco -- A Failure of the Tidal Model
We test whether the structural properties of the nearby dwarf spheroidal
(dSph) galaxy Draco, a well-studied Milky Way companion, can be reconciled with
the suggestion that dSphs are unbound tidal remnants with a large depth extent
along the line of sight. In order to apply the observational test of this
hypothesis suggested by Klessen & Zhao, we use public photometric data from the
Sloan Digital Sky Survey (SDSS) to explore the width of Draco's blue horizontal
branch over a range of areas covering 0.06 square degrees to 6.25 square
degrees centered on Draco. The SDSS database is the only currently existing
database with sufficient depth and area coverage to permit a stringent test of
the tidal models. We show that blue horizontal branch stars extend beyond the
previously inferred limiting radii of Draco, consistent with the observed
absence of a truncated stellar surface density profile of this dSph. We
calculate new models for a galaxy without dark matter, using Draco's
morphological properties as constraints. The resulting models are unable to
reproduce the narrow observed horizontal branch width of Draco, which stays
roughly constant regardless of the field of view. We conclude that Draco cannot
be the remnant of a tidally disrupted satellite, but is probably strongly
dark-matter dominated. (ABSTRACT ABBREVIATED)Comment: 26 pages, 9 figures included, accepted for publication in ApJ,
high-resolution version available at
http://www.aip.de./~ralf/Publications/p22.abstract.htm
Seasonal Variability of Saturn's Tropospheric Temperatures, Winds and Para-H from Cassini Far-IR Spectroscopy
Far-IR 16-1000 m spectra of Saturn's hydrogen-helium continuum measured
by Cassini's Composite Infrared Spectrometer (CIRS) are inverted to construct a
near-continuous record of upper tropospheric (70-700 mbar) temperatures and
para-H fraction as a function of latitude, pressure and time for a third of
a Saturnian year (2004-2014, from northern winter to northern spring). The
thermal field reveals evidence of reversing summertime asymmetries superimposed
onto the belt/zone structure. The temperature structure that is almost
symmetric about the equator by 2014, with seasonal lag times that increase with
depth and are qualitatively consistent with radiative climate models. Localised
heating of the tropospheric hazes (100-250 mbar) create a distinct perturbation
to the temperature profile that shifts in magnitude and location, declining in
the autumn hemisphere and growing in the spring. Changes in the para-H
() distribution are subtle, with a 0.02-0.03 rise over the spring
hemisphere (200-500 mbar) perturbed by (i) low- air advected by both the
springtime storm of 2010 and equatorial upwelling; and (ii) subsidence of
high- air at northern high latitudes, responsible for a developing
north-south asymmetry in . Conversely, the shifting asymmetry in the
para-H disequilibrium primarily reflects the changing temperature structure
(and the equilibrium distribution of ), rather than actual changes in
induced by chemical conversion or transport. CIRS results interpolated to
the same point in the seasonal cycle as re-analysed Voyager-1 observations show
qualitative consistency, with the exception of the tropical tropopause near the
equatorial zones and belts, where downward propagation of a cool temperature
anomaly associated with Saturn's stratospheric oscillation could potentially
perturb tropopause temperatures, para-H and winds. [ABRIDGED]Comment: Preprint accepted for publication in Icarus, 29 pages, 18 figure
Investigation of reactivity of launch vehicle materials with liquid oxygen Quarterly report, 23 Jul. - 22 Oct. 1968
Reactivity of launch vehicle organic materials with liquid oxyge
Investigation of Reactivity of Launch Vehicle Materials with Liquid Oxygen
Impact sensitivity and ignition mechanism of organic compounds in liquid oxygen correlated with chemical and physical propertie
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