1,957,380 research outputs found
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
Sklyanin Bracket and Deformation of the Calogero-Moser System
A two-dimensional integrable system being a deformation of the rational
Calogero-Moser system is constructed via the symplectic reduction, performed
with respect to the Sklyanin algebra action. We explicitly resolve the
respective classical equations of motion via the projection method and quantize
the system.Comment: 14 pages, no figure
Asymptotic behaviour of two-point functions in multi-species models
We extract the long-distance asymptotic behaviour of two-point correlation
functions in massless quantum integrable models containing multi-species
excitations. For such a purpose, we extend to these models the method of a
large-distance regime re-summation of the form factor expansion of correlation
functions. The key feature of our analysis is a technical hypothesis on the
large-volume behaviour of the form factors of local operators in such models.
We check the validity of this hypothesis on the example of the
-invariant XXX magnet by means of the determinant representations for
the form factors of local operators in this model. Our approach confirms the
structure of the critical exponents obtained previously for numerous models
solvable by the nested Bethe Ansatz.Comment: 45 pages, 1 figur
Drawer drive for space shuttle vacuum canister
A sliding drawer type canister was designed to contain long duration exposure facility experiments which require vacuum storage before and after space exposure. The elastomeric seals require high closing loads which are generated through camming levers and transmitted through a spring loaded pressure plate. Lubrication was provided by various dry surface coatings. Higher than expected friction required some redesign after which the assembly functioned well and provided good sealing
System for computing operational probability equations
SCOPE system computes an expression relating the probability of system success to the probabilities of success of its components. It is especially designed for complex system reliability studies
- …