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Nicolaus Copernicus Astronomical Center Research Highlights |
Bartycka 18, 00-716 Warsaw, POLAND |
Table of contents 2012.01.04 Distinction for Solaris Project 2011.06.15 Hasselblad Foundation stipend for Marek Abramowicz 2011.04.15 The shape of the Sagittarius dwarf explained 2011.02.24 First evidence of a gravitational lensing-induced echo in gamma rays with Fermi LAT! 2011.01.20 Mystery of the broad emission lines in quasars explained 2008.07.20 Intranight variability of radio-quiet quasars 2008.04.04 The Torun catalog of galactic pot-AGB objects 2007.04.26 Sixten Heymans for Marek Abramowicz 2007.03.09 Descartes Research Prize 2006 for the project H.E.S.S. 2006.11.30 ESA's gamma-ray observatory Integral has spotted a rare kind of gamma-ray outburst 2006.10.29 Maciej Konacki from Copernicus Centre, Toruń, has won "Złota lampa" Prize 2006.10.23 The Universe is larger then previously though 2006.09.07 2006.07.21 INTEGRAL Satellite and gamma burst 2006.06.01 Cyg X-1: precession of accretion disc 2006.04.11 Microlens in globular cluster M22 2006.03.29 2006.03.14 Eruption of the V838 Mon - an effect of stellar merger 2006.03.14 |
Distinction for Solaris Project Project Solaris, headed by Maciej Konacki form the Copernicus Astronomical Center in Torun was selected as one of five to be presented during the celebration of the 5th Aniversary of European Research Council, at the end of 2012. Hasselblad Foundation stipend for Marek Abramowicz
The Foundation cites the following in its award motivation: Read more on Foundation's web page: The shape of the Sagittarius dwarf explained Dwarf spheroidal galaxies of the Local Group were probably formed by tidal interaction of disky progenitors with the Milky Way and Andromeda. Due to such interactions the dwarfs lose mass and their stellar component transforms into a bar and then an ellipsoid. The dwarf galaxy in Sagittarius is a classical example of such an evolution. According to the presented model, based on an N-body simulation, the Sagittarius dwarf has just passed the second pericenter on its orbit around the Milky Way and its elongated shape is a remnant of a bar formed after the first pericenter. The results of the numerical simulations Full text of the article (Lokas et al., 2010, ApJ, 725, 1516) First evidence of a gravitational lensing-induced echo in gamma rays with Fermi LAT! A. Barnacka, J-F.Glicenstein i Y. Moudden observed for the first time gravitational lensing efect in high energy, gamma rays. More information: Original article published in Astronomy and Astrophysics Mystery of the broad emission lines in quasars explained More information: Intranight variability of radio-quiet quasars Some radio-quiet quasars show clear signs of low amplitude intranight variability. The timescale is surprisingly short for optical variations. Bozena Czerny and collaboratores showed that the only viable explanation is the contribution of a weak variable jet component to the spectrum of radio quiet objects. This supports the view that there is no major intrinsic difference between radio-quiet and radio-loud quasars. The Torun catalog of galactic pot-AGB objects Ryszard Szczerba (CAMK Torun) with collaborators developed the first catalogue of galactic post-AGB objects. The collected information on galactic post-AGB objects will allow to optimize investigations of this still not well understood phase of evolution between Asymptotic Giant Branch (AGB) and planetary nebulae. This is short, albeit very important period of stellar evolution since process of nebulae shapping takes place at its beginning. The on-line version of this catalogue is available Sixten Heymans for Marek Abramowicz
Marek Abramowicz from Copernicus Center (and Goeteborgs Universitet) was awarded
Swedish
Sixten Heymans pris Announcement on the Goeteborgs Universitet web page Descartes Research Prize 2006 for the project H.E.S.S. The research project H.E.S.S. was awarded the 2006 Descartes Prize for Research. The project involves about 100 scientists including polish astrophysicists. The project was named for its achievements in exploring the Universe in the very high energy domain of the electromagnetic spectrum. The success of the H.E.S.S. project was made possible due to a long-time collaboration of the scientific teams from Germany, France, the UK, Ireland, the Czech Republic, Armenia, South Africa and Namibia in designing and building the system of four Cherenkov telescopes in Namibia, which allowed them to carry out observations and collect the data of unprecedented quality. The group of astrophysicists from the Copernicus Astronomical Center and Jagiellonian University joined the H.E.S.S. project in the year 2005. At the beginning their activities concentrated mostly on theoretical research; recently they are being involved in regular observations. More: in the press reselase of European Commission Updated list of members of the polish team in H.E.S.S. ESA's gamma-ray observatory Integral has spotted a rare kind of gamma-ray outburst There are many potential gamma-ray sources in the Galactic Centre. ESA's gamma-ray observatory Integral satellite is now running a Key Programme, in which almost four weeks of its observing time is given over to the study of the galactic centre. On 17 September 2006 Integral, has spotted a rare kind of gamma-ray outburst. The outburst continued to rise in brightness for a few days before beginning a gradual decline that lasted for weeks. Comparing the shape of the light curve of an X-ray nova IGR J17497-2821 to others on file revealed that this was an eruption thought to come from a binary star system in which one component is a star like our Sun whereas the other is a black hole. For more information see the ESA press release Maciej Konacki from Copernicus Centre, Toruń, has won "Złota lampa" Prize Maciej Konacki from NCAC and Jan Awrejcewicz from Lódź Politechnics are the first recipients of a new prize in science. "Złota Lampa" is a prize established and awarded by the Foundation PGNiG - Polskie Górnictwo Naftowe i Gazownictwo - the largest Polish oil and gas exploration and production company. The Prize is awarded in two categories: fundamental science and technical sciences. The monetary value of the Prize is equivalent to approx. 37 000 Euros. Maciej Konacki won the prize for the discovery of an extrasolar planet in a triple stellar system and for the novel technique he has used to achieve this goal. The Universe is larger then previously though
International team of astronomers including Janusz Kałużny and Barbara Mochejska
from the Copernicus Centre and Kris Stanek from Ohio State University (Stanek has
got his M.Sc. from Warsaw University) has determined the distance to the galaxy
M33, for the first time in
a direct way. The distance estimate is based on the observations in the visible
and infrared damain of the two brightest stars in this galaxy, forming a
binary system.
The observations allowed to estimate stellar masses and in consequence their
absolute magnitudes.
Thanks to that the cosmic distance-scale ladder got shorter. The distance to M33 seems
to be about 15% greater, and the size and the age of the Universe as well. See the original publications (Work of A. Sch.-Cz et al.: 2006MNRAS.371.1405H). New Internet tool Created by Michał Frąckowiak from Toruń branch of the Copernicus Centre system wikidot.com offers internauts the space and and the tools for building up both simple personal internet pages, as well as the most advanced internet portals in the Wiki system. Wikidit.com was released in August 2006 but it is already used by approx. 500 internauts from all over the world. It is the most advanced existing system of this type. Main Polish daily Gazeta Wyborcza devoted an article to Wikidot.com (in Polish). INTEGRAL Satellite and gamma burst The INTEGRAL gamma ray satellite has a relatively small field of view of 10X10 degrees. Thus it can catch only a few gamma ray burst per year inside the field of view. An international collboration of researchers from CBK, Warsaw (M. Denis, R. Marcnikowski), Copernicus Astronomical Centre, Warsaw (T. Bulik) and CEA in Saclay (P. Goldoni, Ph. Laurent) have devised a novel data analysis method allowing the detection of gamma ray burst outside the field of view. This has been possible by consdering Compton scattering inside the instrument. For more information see the ESA press release Cyg X-1: precession of accretion disc Cygnus X-1 is historically the first X-ray binary system in which the existence of black-hole was claimed to be true. Its orbital period equals to 5.6 day, and a companion is blue supergiant. A hot (>10e5K) accretion disc is formed around the compact object. The disc is powered by the matter accreting via a focused stellar wind. The wind is mainly responsible for X-ray absorption thanks to the bound-free processes and can be detected well in 1.5-20 keV energy band. A comprehensive analysis of long-term periodic variability of Cyg X-1 using the method of multiharmonic analysis of variance applied to available monitoring data since 1969 in X-ray and radio domain led Pawel Lachowicz, Andrzej Zdziarski, Alex Schwarzenberg-Czerny from the Copernicus Centre and Guy G. Pooley (England) and Shunji Kitamoto (Japan) to the discovery of significant superorbital variability of 151 day. They found it to be: (a) stable for over 65 superorbital cycles and (b) compatible with accretion disc precession. The mechanism of precession is probably sustained via tidal influence of a companion star onto the disc. In addition, a detection of 5.82 day period points at a prograde twist of the disc what, at the moment, appears to be rather difficult to explain from a theoretical point of view. Microlens in globular cluster M22
The Warm Absorber in NGC 3783 Many active galactic nuclei exhibit X-ray features typical of the highly ionized gas called "Warm Absorber". It appears to be stratified, displaying zones of different density, temperature and ionization. Agata Różanska from the Copernicus Center in Warsaw, and z A.C. Goncalves, S. Collin, A.-M. Dumont, M. Mouchet i R.W. Goosmann from the Observatoire de Paris-Meudon have shown that the Warm Absorber in NGC 3783 can be modelled by a single medium in total pressure equilibrium. This is probably the case also for other Warm Absorbers. This work demonstrated that the TITAN numerical code, deweloped by this team is well adapted to the study of Warm Absorbers in active galactic nuclei. It opens prospects for the use of TITAN by a larger community. Eruption of the V838 Mon - an effect of stellar merger In January 2002 the luminosity of V838 Mon increased to 600 thousand times larger then the luminosity of the Sun. The star became the brightest star in the Milky Way. Similar phenomena were observed earlier: M31 RV (erupted in 1988), V4332 Sgr (erupted in 1994). Roman Tylenda (Copernicus astronomical Center in Toruń) and Noam Soker (Technion Institute of Technology, Israel), studied three models of the eruption of V838 Mon: thermonuclear runaway on an accreting white dwarf (nova-like event), He-shell flash in a post asymptotic giant branch star (born-again AGB) and merger of stars. Tylenda and Soker proved the first two hypotheses can not account for the majority of the observed properties of the object V838 Mon and that the stellar merger model can account for all of them. Theory predicts there are 1-2 such events in our Galaxy each year. It seems that the observed frequency of V838 Mon type events is in agreement with this prediction. Cosmic Topological Dark Energy? Two of the biggest open questions in physical cosmology are the physical interpretation of the measured dark energy, and the still uncertain global shape of comoving space, especially including its topology. Stanislaw Bajtlik (Copernicus Astronomical Centre, Warsaw), Boudewijn F. Roukema, Agnieszka Szaniewska, Helena Jurkiewicz (Copernicus Astronomy Centre, Torun) and Marek Biesiada (University of Silesia, Katowice), used a weak field (Newtonian) approximation of gravity and considered the gravitational effect from distant, multiple copies of a large, collapsed (virialised) object today (i.e. a massive galaxy cluster), taking into account the finite propagation speed of gravity, in a flat, multiply connected and assuming that due to a prior epoch of fast expansion (e.g. inflation), the gravitational effect of a distant copies is felt locally, from beyond the naively calculated horizon. Results: the authors find that the residual newtonian gravitational force provides an effect that repels test particles from the cluster. proportionally to the distance from the cluster. This effect is algebraically similar to that of a cosmological constant and could be interpreted as an effect repelling a test object at comoving distance x from the nearest dense nodes of the cosmic web of density perturbations. The amplitude of the effect, expressed in terms of the pressure-to-density ratio w of the equation of state in a FLRW universe, is of order -(x/L)^3, where L is the size of the fundamental domain, i.e. of the Universe. Clearly, |w| << 1. |
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