3 research outputs found
Physical properties of two compact high-velocity clouds possibly associated with the Leading Arm of the Magellanic System
We observed two compact high-velocity clouds HVC 291+26+195 and HVC
297+09+253 to analyse their structure, dynamics, and physical parameters. In
both cases there is evidence for an association with the Leading Arm of the
Magellanic Clouds. The goal of our study is to learn more about the origin of
the two CHVCs and to use them as probes for the structure and evolution of the
Leading Arm. We have used the Parkes 64 m radio telescope and the Australia
Telescope Compact Array (ATCA) to study the two CHVCs in the 21 cm line
emission of neutral hydrogen. We present a method to estimate the distance of
the two CHVCs. The investigation of the line profiles of HVC 297+09+253 reveals
the presence of two line components in the spectra which can be identified with
a cold and a warm gas phase. In addition, we find a distinct head-tail
structure in combination with a radial velocity gradient along the tail,
suggesting a ram-pressure interaction of this cloud with an ambient medium. HVC
291+26+195 has only a cold gas phase and no head-tail structure. The ATCA data
show several cold, compact clumps in both clouds which, in the case of HVC
297+09+253, are embedded in the warm, diffuse envelope. All these clumps have
very narrow HI lines with typical line widths between 2 and 4 km/s FWHM,
yielding an upper limit for the kinetic temperature of the gas of T_max = 300
K. We obtain distance estimates for both CHVCs of the order of 10 to 60 kpc,
providing additional evidence for an association of the clouds with the Leading
Arm.Comment: 11 pages, 6 Postscript figures, 2 tables; accepted for publication in
Astronomy & Astrophysic
Signal Integrity: Efficient, Physics-Based Via Modeling: Integration of Striplines
In the first article of this series, principles and methods of physics-based via modeling were discussed. It was shown how the electromagnetic behavior of vias can be captured by an equivalent circuit based modeling approach that describes all relevant full-wave effects. In this follow-up article, the authors present an approach to integrate striplines into the physics-based via model. The striplines can be located at any layer of the stackup and they may constitute both single and multiconductor transmission lines. The integration of striplines extends the via representation to a full, efficient interconnect model of, for instance, printed circuit board signal links. An intuitive integration approach at a circuit simulator level and application examples are discussed in this article as well