Wednesday Colloquium


"Contact Binary Stars: 45 Years after Lucy"

Stefan Mochnacki (University of Toronto)

In 1968, Leon Lucy proposed a compelling model for W U Ma stars involving a close binary surrounded by a common convective envelope. I will review what we now know about contact binaries, and whether this model has fundamental difficulties. I also will briefly touch upon the challenges of computing light curves and spectra when space-based observations are a hundred times more precise than theoretical calculations using methods first devised by Lucy.


"Forty years of the Shakura-Sunyaev ISCO paradigm "

Marek Abramowicz (NCAC, Warsaw)

One of the key concepts in the Shakura-Sunyaev black hole accretion disk model is the existence of ISCO. I will briefly discuss ISCO's original meaning, and at length a few recent papers that address a relevance of the concept of the "inner disk edge" in the context of the magneto-rotational (Balbus-Hawley) instability.


"Galactic Wind Haze"

Peter L. Biermann (MPI for Radioastronomy, Bonn, Germany)

We present a comprehensive interpretation of the Galactic wind haze at radio and gamma-ray wavelengths: We propose that the solution is an unsteady Galactic wind, driven by cosmic rays and massive star activity. With this ansatz we discuss i) the Planck and WMAP haze, ii) the Fermi haze and the Fermi bubble, iii) the cosmic ray electron and positron data, iv) the 511 keV emission line, v) the 130 GeV feature, vi) the magnetic fields in the wind, vii) the radial profile, viii) the energetics, and ix) the non-stationarity and spectrum of magnetic irregularities in the wind.


"Radio and optical monitoring of blazars and the RT90 progress report"

Andrzej Kus (Astronomy Center, Nicolaus Copernicus University, Toruń)

A progress reports and recent achievements will be presented on two subjects: 1. Radio monitoring of Fermi sources on Torun 32m RT in combination with similar programs performed at OVRO (Caltech) 40m and MPIfR 100m RT. A new development to observe polarization at optical range within RoboPol collaboration (Crete University, Caltech, MPIfR, UMK) using Skinakas 1.3m telescope will be described. The program should start this spring in semi and then full automatic modes to routinely observe ~300 blazars and ToO transients. Torun has 25% share in the polarimeter investment. 2. Preparatory work and the current situation with the proposal for large Polish radio telescope will be detaily presented. The chances for the success are high both in funds availability as in the country's technical capabilities. The concept study including 3D computer model of RT90+ and the scientific programs will be reviewed. The project creates great challenge for the logistics, technology development and broad aspects research. The new telescope will be an important part of European research infrastructure, sustainable for many decades and for variety of present and future research programs.