Wednesday Colloquium


"Climate physics - global warming"

Szymon Malinowski (Institute of Geophysics, Warsaw University)

The talk is planned as an overview of contemporary climate physics. In the first part physical principles of the climate system will be reminded. Then history of climate science, beginning from Joseph Fourier through John Tyndall, Svante Arrhenius to Edward N. Lorenz and modern times will be stressed. Observing systems and theoretical methods commonly used in climate research will be discussed after the introduction. The particular attention will be paid to attribution of the recent climate change . Advances in climate science in context of the forthcoming 5th Assessment Report of the Intergovernmental Panel on Climate Change will be summarized in the final part of the talk.


"Winds versus accretion disk atmospheres in GBHBs"

Agata Różańska (NCAC, Warsaw)

We show that continuum X-ray spectrum of 4U 1630-472 being in the high/soft state with iron absorption lines can be satisfactorily modeled by the spectrum from an accretion disk atmosphere. Our models of disk emission seen at different viewing angles, computed using full radiative transfer code ATM21 are then fitted to high resolution X-ray spectra of 4U 1630-472 obtained by SUZAKU satellite. We model continuum and line spectra using a single model. Iron absorption line profiles computed with natural, thermal and pressure broadenings match very well observations. According to any global disk models considered for the mass of central object of the order 10 solar masses or less, the effective temperature of the inner radii reaches $10^7$K. In such a case possible origin of absorption lines from accretion disk atmospheres should be taken into account in modeling of winds in X-ray binaries. During talk I will discuss the wind model versus accretion disk atmospheres in GBHBs.


"Investigating the intriguing A-type stars"

Simon Murphy (University of Central Lancanshire)

The A-type stars exhibit a plethora of fascinating phenomena, offering testbeds to an array of research areas. The Am and Ap stars have chemical peculiarities that are influenced by radiation pressure, diffusion and mixing. The magnetic Ap stars display the effects of magnetic fields on astrophysical plasmas, strongly influencing processes such as convection. The range of rotation velocities stretches from stars rotating at walking speed to those on the border of Keplerian break-up. All of these properties influence perhaps the most important observed phenomenon of all: pulsation. The variety of pulsation classifications found here, at the junction of the classical instability strip and the main sequence, is the densest of the whole HR-diagram and is being probed at revolutionary precision with the Kepler Space Telescope. In this presentation, we will review these fascinating phenomena along with some exciting new results obtained with Kepler.


"The MOST and BRITE satellite projects"

Sławomir Ruciński (University of Toronto)

The MOST and BRITE satellite projects The satellite project MOST was started in 1997 by a successful application to the Canadian Space Agency. It was launched in 2003 and since then has provided high precision (10-5 to 10-3), continuous (up to 2 months), high cadence (typically 6 times per minute), photometric data on variability of bright stars of 1 to 12 mag. MOST has been the first photometric micro-satellite (<100 kg) and the important lessons from its performance have been implemented in planning of the CoRoT and Kepler missions. The satellite project BRITE, originally conceived as a very inexpensive mission of two nano-satellites (<10 kg), has grown since its inception in 2004 into the BRITE Constellation of 6 satellites, to be launched in pairs by Austria (already in orbits, since 24 February 2013), Poland and Canada in 2013 - 2014. The BRITE satellites will concentrate on continuous photometry of brightest stars (<4 mag) in longer times scales than MOST, typically hours to several months. The talk will describe how it came to both projects and what are their main scientific advantages and weaknesses.