21 research outputs found
A Wide Field, Low Frequency Radio Image of the Field of M31: II. -- Source Classification and Discussion
We have previously presented the results of a 325 MHz radio survey of M31,
conducted with the A-configuration of the Very Large Array. In this survey, a
total of 405 radio sources between <6" and 170" in extent were mapped with a
resolution of 6" and a sensitivity of ~0.6 mJy/beam. Here, we compare the
resultant source list and image with other radio, IR, optical, X-ray
observations and catalogs of the region. Through this, we were able to identify
five supernova remnant (SNR) candidates and three pulsar wind nebula (PWN)
candidates in M31, as well as three Milky Way radio stars, a possible Milky Way
Planetary Nebula, and a bevy of interesting extragalactic objects: a BL Lac, a
Giant Radio Galaxy, a galaxy merger, and several high-z radio galaxy
candidates. In addition, a large number of compact (<6") extremely steep
spectrum sources () were
detected whose nature is unknown.Comment: 30 pages, 23 tables, + 18 figures. Low-resolution figures are
available here in .jpg form. ApJS accepted, to be published in August 2005,
v159 2 issu
Variable Stars in Galactic Globular Clusters
Based on a search of the literature up to May 2001, the number of known
variable stars in Galactic globular clusters is approximately 3000. Of these,
more than 2200 have known periods and the majority (approximately 1800) are of
the RR Lyrae type. In addition to the RR Lyrae population, there are
approximately 100 eclipsing binaries, 120 SX Phe variables, 60 Cepheids
(including population II Cepheids, anomalous Cepheids and RV Tauri) and 120
SR/red variables. The mean period of the fundamental mode RR Lyrae variables is
0.585, for the overtone variables it is 0.342 (0.349 for the first-overtone
pulsators and 0.296 for the second-overtone pulsators) and approximately 30%
are overtone pulsators. These numbers indicate that about 65% of RR Lyrae
variables in Galactic globular clusters belong to Oosterhoff type I systems.
The mean period of the RR Lyrae variables in the Oosterhoff type I clusters
seems to be correlated with metal abundance in the sense that the periods are
longer in the more metal poor clusters. Such a correlation does not exist for
the Oosterhoff type II clusters. Most of the Cepheids are in clusters with blue
horizontal branches.Comment: 45 pages, 10 figures, to be published in AJ November 200
New approach to the LaxâWendroff modified differential equation for linear and nonlinear advection
METHOD FOR DETERMINATION OF THERMAL CHARACTERISTICS OF THE LAYER OF GRANULAR MEDIA WITH ELEMENTS OF PULSED THERMAL NDT
At the Department of Food Production of Murmansk State Technical University (MSTU) was developed a method of producing smoke fuel using infrared energy supply. The method provides a stable temperature pyrolysis of wood fuel is less than 400 ° C. Kinetic of the heating layer of fuel (wooden chips) is affected by chip's density and moisture content. The method of calculating of the optimum modes of smoke produce, which is based on a system of differential equations of heat and mass transfer in the IR smoke generator, was previously proposed. The system of equations includes thermal characteristics (TC) of the fuel layer (e.g. specific heat, thermal conductivity, thermal diffusivity). The exact definition of these characteristics affect the accuracy of the experimental calculation of optimal process conditions with use of the developed software. A definition of layer's TC by a method with elements of pulsed thermal NDT. The use of thermal imager is proposed for measuring the temperature of the irritated surface of the porous wooden chip's lawyer