Wednesday Colloquium

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"Cosmic butterflies: the product of tempestuous stellar marriages"

David Jones (Instituto de Astrofísica de Canarias)

Planetary nebulae are some of the most strikingly beautiful astrophysical phenomena known, gracing many a glossy-paged, coffee-table book and earning them the nickname "cosmic butterflies". It is now clear that a significant fraction of these objects originate from a binary evolutionary pathway, with some theories even going as far as to say that binarity may be a prerequisite for all but the most massive stars to form a planetary nebula. In this seminar, I will begin by outlining some fundamentals of close binary evolution and how they relate to the formation of planetary nebulae. I will then go on to discuss some of our most interesting results, what they can tell us about the common envelope phase of close binary evolution, and the growing connections between these systems and other binary phenomena including novae and supernovae type Ia.

"Discovery of a new class of pulsating stars"

Paweł Pietrukowicz (Astronomical Observatory, Warsaw University)

Thousands of pulsating stars have been detected in the Milky Way and other galaxies of the Local Group over the last decades mainly thanks to large-scale variability surveys. It seemed that all types of pulsating stars had been recognized. By monitoring about one billion stars in the sky, the OGLE survey has discovered extremely rare, short-period objects whose properties do not fit to any class of known pulsators. Theory shows that the newly discovered objects are evolved low-mass stars with a giant-like structure, but their origin remains a mystery.

"A simple approach to gravitational wave data analysis"

Tomasz Bulik (Astronomical Observatory, Warsaw University)

The recent discovery of binary black hole coalescence by LIGO is based on a few cycles seen in a fraction of a second. I will show how the information about the binary can be inferred from the observed variation of the signal in time using only basic physical arguments.


Benoit Famaey (Observatoire Astronomique de Strasbourg)


Jonathan Zrake (Columbia University)


M.Ali Alpar (Sabanci University, Istanbul)