Wednesday Colloquium


"Studies of methanol maser sources in high-mass star-forming regions - discoveries based on Torun blind survey"

Anna Bartkiewicz (Astronomy Centre, UMK)

I will summary our studies of methanol maser sources that were discovered using Torun 32-m dish (Szymczak et al. 2000, 2002). We imaged selected 31 sources using the European VLBI Network and discovered a new class of objects - the ring-like structures. Next, we carried out four projects using radio interferometers VLA and VLBA as well as telescopes GEMINI in order to investigate where the exciting stellar sources lie with respect to the masers and to know the nature of massive young stellar objects.


"New and comprehensive ways to constraining the co-evolution of Black Holes and Galaxies"

Francesco Shankar (Max Planck Institute for Astrophysics in Garching)

Supermassive black holes (SMBHs) seem to be ubiquitous at the center of all galaxies which have been observed with high enough sensitivity with HST. SMBH masses are tightly linked with the masses and velocity dispersions of their host galaxies. Also, SMBHs are considered to be the central engines of active galactic nuclei (AGN). It is however still unclear how SMBHs have grown and if they have co-evolved with their hosts. In my talk I will derive, in ways independent of specific models, constraints on how SMBHs must have evolved within their dark matter halos. I will describe the accretion history of SMBHs from z~6 to z~0 by interconnecting a variety of data sets, including the AGN luminosity function, their clustering properties, and Eddington ratio distributions. I'll show results obtained through a novel numerical code which evolves the SMBH mass function and clustering adopting broad distributions of Eddington ratios. I will finally insert SMBH evolution in a wider cosmological framework for galaxy evolution directly constrained by the Sloan Digital Sky Survey.


"Solar like oscillations in Delta Scuti stars"

Victoria Antoci

Asteroseismology allows to access the most hidden part of the universe - the interior of stars. The outer convection zone in the Sun, for example, is known to generate acoustic noise in a broad frequency range, leading stochastically excited pulsation. From ground-based observations but also from space missions such as CoRoT and Kepler it is known that many solar-type stars show the same type of oscillations. As stellar mass and effective temperature increase the convective outer layer decreases. The transition zone from deep and effective to shallow convective outer zone takes place in the classical instability strip where the delta Scuti stars are located. These stars exhibit pulsations driven by an opacity mechanism acting like a heat engine. Theoretical models predicted solar-like oscillations to be still present in the very cool delta Scuti stars, but were never observed so far. Here we present the first evidence of stochastically excited oscillations in such a star, provided by NASA's Kepler satellite. Surprisingly, the measured effective temperature is higher than models predict, making this star a unique astrophysical laboratory to test our models on convection. Furthermore divers regions of the star can be sounded seismically as stochastically excited oscillations and pulsation driven by the opacity mechanism excite different radial overtones which penetrate into different depths of the star


"Ptaki w naszym otoczeniu"

Andrzej Kruszewicz (Warszawski Ogród Zoologiczny)


"20th Century Global Warming - Anthropogenic or Solar?"

Nir J. Shaviv (Racah Institute of Physics, Hebrew University of Jerusalem)

The 20th Century has seen a notable temperature rise, generally attributed to the greenhouse effect of anthropogenic gases, and a future "business as usual" policy is generally believed to be catastrophic. I will show, however, that the story is not that simple. I will address the following questions, all of which have a far from trivial and often surprising answer: How large is the greenhouse effect? Could some of the temperature rise be natural and not anthropogenic? If so, what is this natural driver? How sensitive really is Earth's climate? What should we expect in the future? How effective will the implementation of a cap and trade agreement be?