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M. Mikolajewski

Publications and source records attributed to M. Mikolajewski.

13 recordsLinked to original sources
arXiv2015

SALT observations of southern post-novae

We report on recent optical observations of the stellar and the nebular remnants of 22 southern post-novae. In this study, for each of our targets, we obtained and analysed long-slit spectra in the spectral range 3500-6600 A and in H$α$+NII narrow-band images. The changes in the emission lines' equivalent widths with the time since the outburst agree with earlier published results of other authors. We estimated an average value $α$=2.37 for the exponent of the power law fitted to the post-novae continua. Our observations clearly show the two-component structure of the V842 Cen expanding nebulae, owing to the different velocities of the ejected matter. We discovered an expanding shell around V382 Vel with an outer diameter of about 12 arcsec.

astro-ph.SR↗
arXiv2014

The 2014 Eclipse of EE Cep. Announcement for a Third International Observational Campaign

EE Cep is a unique system in which a Be star is eclipsed by a dark dusty disk, making this star similar to the famous epsilon Aur in many respects. The depth and the duration of the EE Cep eclipses change to a large extent. The last two eclipses were observed in the framework of extensive international campaigns. The joint analysis of these campaigns data and historical photometry, enabled us to propose a model of this system, which implies a disk precession with a period approximately 11-12 times larger than the orbital period. This model predicts that the forthcoming eclipse should be among the deepest observed, reaching about 2 mag. The next eclipse approaches - the photometric minimum should occur around August 23, 2014. Here we would like to announce a new, third international campaign with purpose to verify the disk precession model and to put more constraints on the physical parameters of this system.

astro-ph.SR↗
arXiv2010

Multicolor photometry of SU UMa and U Gem during quiescence, outburst and superoutburst

The results of time-resolved observations of SU UMa and U Gem obtained over two-years are presented. Both stars are prototypes of different classes of dwarf novae. We studied brightness variations on different time scales: orbital, QPO and flickering. The multicolor BVRI photometry allows to distinguisch the geometrical and physical sources of these variations.

astro-ph.SR↗
arXiv2010

V2467 Cygni as possible intermediate polar

We present the results of unfiltered and UBVR_cI_c band CCD photometry fast nova V2467Cyg. Our analysis of the data gives two distinct frequencies corresponding to periods of ~3.8h and ~35 min. The observed light curve of V2467 Cyg is typical for an intermediate polar.

astro-ph.SR↗
arXiv2010

V2491 Cyg - a possible recurrent nova ?

Nova V2491 Cyg was discovered on April 10.72 UT 2008 (Nakano, 2008). Here we present spectrophotometric premises that V2491 Cyg can be a good candidate for recurrent nova (RNe). Its properties are compared to five well known RNe with red dwarf secondaries (U Sco, V394 Cra, T Pyx, CI Aql, IM Nor) and recently confirmed as recurrent nova V2487 Oph (Pagnotta et al.,2008). Photometric $U, B, V, R_C, I_C$ and moderate resolution (R$\sim 1500$) spectral observations of V2491 Cyg were carried out in the Torun Observatory (Poland) between April 14 and May 20 2008.

astro-ph.SR↗
arXiv2010

Ellipsoidal effect in the symbiotic star YY Her

A new estimation of the orbital period of YY Her on the base of our and published observations is presented. Phased light curves in RI bands show evidently ellipsoidal effect connected with the tidal distortion of the giant surface.

astro-ph.SR↗
arXiv2010

Photometric search of orbital periods in symbiotic stars

We present UBVRI photometry of three symbiotic stars ZZ CMi, TX CVn and AG Peg carried out from 1997 to 2008 in Piwnice Observatory near Torun. To search orbital periods of these stars Fourier analysis was used. For two of them, TX CVn and AG Peg, we have confirmed the earlier known periods. For ZZ CMi we found a relatively short period 218.59 days. Assuming, that the orbital period is twice longer (P=437.18 days), the double sine wave in the light curve can be interpreted by ellipsoidal effect.

astro-ph.SR↗
arXiv2009

Multi-ring structure of the eclipsing disk in EE Cep - possible planets?

The photometric and spectroscopic observational campaign organized for the 2008/9 eclipse of EE Cep revealed features, which indicate that the eclipsing disk in the EE Cep system has a multi-ring structure. We suggest that the gaps in the disk can be related to the possible planet formation.

astro-ph.SR↗
arXiv2006

Searching for flickering variability in several symbiotic stars and related objects: BX Mon, V471 Per, RS Oph, V627 Cas, CI Cam V886 Her, Z And, T CrB, MWC 560, V407 Cyg

UBVRI photometry observations of 10 symbiotic stars and related objects obtained in the period 2002-2003 are presented. Analysing differential light curves we found rapid light variations with timescales of tens of minutes and significant amplitudes in the well-known flickerers MWC 560, RS Oph, V407 Cyg and T CrB. MWC 560 and V407 Cyg demonstrate quasi periodic oscillations (QPO) with similar amplitudes and timescales. Flickering and unusual flare in V627 Cas as well as some indications of flickering presence in BX Mon are detected. The existence of 29 minutes oscillations in Z And with an amplitude about 0.02 mag in U band is confirmed. Only one symbiotic star, V471 Per, and both non symbiotic, CI Cam and V886 Her seem to be constant on flickering timescales. Nevertheless, small night to night changes in the brightness of V886 Her were observed as well.

astro-ph↗
arXiv2003

The 2003 eclipse of EE Cep is coming. A review of past eclipses

EE Cep is an eclipsing binary with a period of 5.6 years. The next eclipse will occur soon, in May-June 2003, and all available past eclipses were collected and briefly analysed. EE Cep shows very large changes of the shape and the depth of minima during different eclipses, however it is possible to single out some persistent features. The analysis suggests that the eclipsing body should be a long object surrounded by an extended semi-transparent envelope. As an explanation, a model of a precessing optically thick disc, inclined to the plane of the binary orbit, is invoked. The changes of its spatial orientation, which is defined by the inclination of the disc and the tilt, induced most probably by precession of the disc spin axis with a period of about 50 years, produce strange photometric behaviour of this star. The H_alpha emission, and possibly the NaI absorptions, show significant changes during several months outside of the eclipse phase.

astro-ph↗
arXiv2002

Peculiar outburst of the newly revealed variable star V838 Mon

We present photometric and high- and low-resolution spectroscopic observations of the unusual outburst of V838 Mon. The data were collected at the NAO Rozhen, Bulgaria and at the Torun Observatory, Poland. Analysis of the peculiar behavior of the spectrum of the star is given. The star's radial velocity of +60 km/s is derived. A brief discussion concerning the nature of the object is also given.

astro-ph↗
arXiv2002

The double outburst of the unique object V838 Mon

We present spectroscopic and photometric observations of the recent peculiar outburst of V838 Mon, carried out at Rozhen and Torun observatories. Our data cover a period of three months beginning just before the second eruption. The evolution of the outburst is divided into four phases. The changes of particular spectral features for each of these phases are shortly discussed.

astro-ph↗