Wednesday Colloquium


"Pulsar Wind Nebula G21.5-0.9 seen in the infrared"

Anna Zajczyk (Copernicus Astronomical Centre, Toruń)

The young PWN G21.5-0.9, heavily obscured in the optical due to its position in the inner Galaxy, reveals its beauty and complexity in the infrared. Images taken with ISAAC - VLT in the 1.64 micron [FeII] line show diffuse emission within the PWN which presumably originates from shocked ejecta. Spitzer, AOB-KIRĆFHT and polarimetric imaging, on the other hand, reveals a compact, strongly polarised nebula coincident with the X-ray core observed by Chandra. The measurements of the polarisation angle yields unique information on the magnetic geometry near the pulsar wind termination shock. The case of PWN G21.5-0.9 points to the infrared band as a promising window for observing optically obscured PWNe.


"The long term evolution of a planetary system with energy dissipation"

Cezary Migaszewski (Centre for Astronomy, N. Copernicus University, Toruń)

The study of the evolution of a planetary system with short-period planets in the time-scales of gigayears requires taking into account the dissipation of mechanical energy both in the star and in the planets. I will discuss the mechanism of energy loss as well as its consequences on the long term dynamics of a system consisting of a Sun like star and a hot Jupiter.


"Satellite Mission Planck: Description, Scientific Goals, and Early Results"

Krzysztof Górski (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA and Warsaw University Observatory)

Since August 2009 Planck has been observing the sky at frequencies from 30 to 857 GHz, measuring its principal target - the cosmic microwave background, but also everything else in the universe that radiates at these frequencies. I will describe the design and scientific goals of the mission, and the first scientific results from Planck, presented in Jan. 2011, covering a wide range of galactic and extragalactic astrophysics.


"The radio-X-ray correlation in black-hole binaries and the formation of jets"

Andrzej Zdziarski (Copernicus Astronomical Centre, Warsaw)

The radio flux in the hard state of black hole binaries is strongly correlated with the X-ray flux. The character of this correlation is found to strongly depend on the X-ray energy, as well as the correlation is found to extend to the soft spectral state, using data from Cyg X-1. The results imply that the jet is formed by the relativistic electrons of the Comptonization corona/hot flow, and rule out models in which the observed X-rays are emitted by the jet.


"GHz-Peaked-Spectrum Galaxies as sources of high energy emission"

Rafał Moderski (Copernicus Astronomical Centre, Warsaw)

I will present a simple dynamical description of young and compact (less then one kpc) radio galaxies, consisting of relativistic jet propagation into a uniform gaseous medium in the central parts of an elliptical host. The model will allow to discuss the broad-band lobe emission with a strong and complex high-energy component. I will also present X-ray and gamma-ray observations to support the model.