Wednesday Colloquium


"Fulerens in space"

Ryszard Szczerba (Copernicus Astronomical Centre, Toruń)

The first fullerenes (C60, C70, etc.) were synthesized in lab in mid-eighties. For this discovery the team (Kroto, Curl, and Smalley) was awarded by Nobel Price in Chemistry in 1996. Since then fullernes were discovered in minerals and meteorities, but only in 2010 in Space using data from Spitzer Space Telescope. Surprisingly, they were found only in H-rich environments including planetary nebula in SMC. During this talk the recent discoveries of fullerenes in Space will be reviewed.


"The doubling of the superorbital period of Cyg X-1"

Andrzej Zdziarski (Copernicus Astronomical Centre, Warsaw)

In addition to X-ray and radio periodicity related to the orbital motion, Cyg X-1 shows a longer X-ray/radio period, so-called superorbital, presumably related to precession of its accretion disc and jet. Recently, Cyg X-1 underwent a striking doubling of this period from about 150 d to about 300 d, which presents a challenge to theoretical models. The periodicity appears as changes in the normalization of an intrinsic spectrum of constant shape, which implies it is not due to periodic changes of the accretion rate.


"V1309 Sco: merger of a contact binary"

Romuald Tylenda (Copernicus Astronomical Centre, Toruń)

Stellar mergers are expected to take place in numerous circumstences in the evolution of stellar systems. In particular, they are considered as a plausible origin of stellar eruptions of the V838 Mon type. V1309 Sco is the most recent eruption of this type in our Galaxy. The object was discovered in September 2008. It appears that V1309 Sco has been photometrically observed in course of the OGLE project since August 2001. The progenitor of the object was variable and we find out that it was a contact binary with an orbital period of ~1.4 day. The period was systematically decreasing with time. Similarly the light curve of the binary was also evolving. The system evolved toward its merger. The violent phase of the merger, marked by the systematic brightenning of the object, started in March 2008, i.e. half a year before the outburst discovery. We also investigate the observations of V1309 Sco during the outburst and the decline and show that they can be fully accounted for within the merger hypothesis. Thus, for the first time in the history, we show, from direct observations, that contact binaries indeed end up by merging into a single object, as it was suggested in numerous theoretical studies of these systems. Our study also shows that stellar mergers indeed result in eruptions of the V838 Mon type.


"What was the last Nobel Prize in physics given for?"

Jacek Baranowski (Department of Physics, Warsaw University)