22,689 research outputs found
Combining ray-trace and diffraction analysis: A design example
An example is presented of using a combined ray trace and diffraction modeling code to simulate effects of objective-lens tilt in an optical data storage device. In some cases, neither ray-trace analysis nor diffraction analysis can give an adequate description of an optical system. The designer that is faced with the problem of analyzing such a system is forced to use a ray-trace program to determine aberrations in the exit pupil and then introduce aberration coefficients into a diffraction model that simulate the propagation. This approach was found rather awkward, especially if complicated aberrations are present. Our approach is to integrate a diffraction analysis and a ray-trace description of an optical path into one program. Our design is taken from a data storage application, where we must analyze the effects of objective-lens tilt
The Stellar Population of Stripped Cluster Spiral NGC 4522: A Local Analog to K+A Galaxies?
We present observations of the stripped Virgo Cluster spiral NGC 4522, a
clear, nearby example of a galaxy currently undergoing ISM-ICM stripping.
Utilizing SparsePak integral field spectroscopy on the WIYN 3.5m telescope and
GALEX UV photometry, we present an analysis of the outer disk (r > 3 kpc)
stellar population of this galaxy, beyond the HI and Halpha truncation radius.
We find that the star formation in the gas-stripped outer disk ceased very
recently, ~100 Myr ago, in agreement with previous claims that this galaxy is
currently being stripped. At the time of this stripping, data and models
suggest that the galaxy experienced a modest starburst. The stripping is
occurring in a region of the cluster well outside the cluster core, likely
because this galaxy is experiencing extreme conditions from a dynamic ICM due
to an ongoing sub-cluster merger. The outer disk has a spectrum of a K+A
galaxy, traditionally observed in high-redshift cluster galaxies. In the case
of NGC 4522, a K+A spectrum is formed by simple stripping of the interstellar
gas by the hot intracluster medium. These data show K+A spectra can be created
by cluster processes and that these processes likely extend beyond the cluster
core.Comment: 5 pages, 3 figures, accepted for publication in ApJ Letter
Submarine groundwater discharge: an unseen yet potentially important coastal phenomenon
In collaboration with researchers from Florida
State University, Florida Sea Grant introduces an important but poorly known topic:
submarine groundwater discharge. Although nearly invisible, submarine
groundwater discharge influences coastal systems. This brochure helps explain this important phenomenon. (8pp.
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