A. Majczyna - Academia.edu (original) (raw)

Papers by A. Majczyna

AIP Conference Proceedings, 2009

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2012, 2012

ABSTRACT We analyse burst of MXB 1728-34 obtained by the RXTE PCA instrument during the observati... more ABSTRACT We analyse burst of MXB 1728-34 obtained by the RXTE PCA instrument during the observational period from 1995 to 2005. Each spectrum was integrated over 0.25 second and was fitted to the extensive grid of atmospheric models after background subtraction. Theoretical model spectra were calculated by the ATM code for various chemical compositions, effective temperatures from 107 K to 3×107 K and surface gravities from critical gravity up to log g = 15.0 (cgs units). As the result of the fitting procedure we obtained the surface redshift z and the surface gravity log g simultaneously for each trial set of parameters. Therefore, we are able to calculate mass and radius of the neutron star in MXB 1728-34. Many satisfactory fits were obtained for each chemical composition, but for models with iron abundance 100 times greater than the solar value fits were better than others. For this chemical composition we recommend that mass and radius of the neutron star is in the range: M = 0.103 - 1.564 Mʘ and R = 1.745 - 10.620 km.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

ABSTRACT We present the first few steps of creation the second edition of the variable stars cata... more ABSTRACT We present the first few steps of creation the second edition of the variable stars catalogue, based on the "Pi of the Sky" data, collected during two years 2006-2007. We have chosen - 3000 variable star candidates from about 1.5 million objects.

EAS Publications Series, 2013

ABSTRACT Pi of the Sky is a system of wide field-of-view robotic telescopes which search for shor... more ABSTRACT Pi of the Sky is a system of wide field-of-view robotic telescopes which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system is designed for autonomous operation, follows the predefined observing strategy and adopts it to the actual conditions. We describe the current status of telescopes located in Chile and Spain and prospects for future development.

ABSTRACT We present determinations of masses, radii and bolometric luminosities for DA white dwar... more ABSTRACT We present determinations of masses, radii and bolometric luminosities for DA white dwarfs observed for the ESO SN Ia Progenitor Survey. Masses and radii of 513 stars were determined from their effective temperatures and surface gravities, obtained by Koester et al. (2009 [6]). We have used a grid of theoretical mass‐radius relations for carbon and oxygen core stars with hydrogen envelopes derived by Panei et al. (2000 [10]).

We present model atmospheres and theoretical spectra for X-ray bursters. Our models include the e... more We present model atmospheres and theoretical spectra for X-ray bursters. Our models include the effects of Compton scattering on free electrons. The atmospheres have compositions that are mixtures of hydrogen, helium, and iron. For our models the ratio of color temperature, TcT_cTc, to effective temperature, TeffT_{eff}Teff, is in the range 1.2 - 1.8. This ratio depends on TeffT_{eff}Teff, surface gravity, and iron abundance. For fixed TeffT_{eff}Teff and surface gravity, models with non-zero iron abundance exhibit values of Tc/TeffT_c/T_{eff}Tc/Teff that are slightly lower than pure hydrogen-helium models.

We present a new catalogue of masses, radii and bolometric luminosities for hot DA white dwarfs o... more We present a new catalogue of masses, radii and bolometric luminosities for hot DA white dwarfs observed by the Sloan Digital Sky Survey (Data Release 4). Masses and radii of 7134 non-magnetic stars were determined from their observed effective temperatures Teff and surface gravities log g by the spectroscopic method. We have used here the grid of theoretical mass-radius relations for carbon-core stars with hydrogen-envelopes derived by Panei et al. (2000). Mass distribution of DA white dwarfs with Teff >= 12000 K has one maximum at M=0.549 M&sun;. However, we discovered the existence of the secondary maximum at about 0.393 M&sun; for hotter white dwarf stars. We also turn attention to low-mass white dwarfs (M

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2010, 2010

ABSTRACT We presented preliminary results for our catalogue of the variable stars from the 2006-2... more ABSTRACT We presented preliminary results for our catalogue of the variable stars from the 2006-2007 "Pi of the Sky" data. Our catalogue contains more than 1 000 variable stars of different type. The most numerous group in our catalogue are eclipsing variables (515) whereas pulsating variables are less numerous (292). Significant group consists stars classified simply as "variable" (180). For these stars we can not be able to determine more detailed type of the variability. Our classification was based on the shape of the light curve, as in the GCVS catalogue. However, some stars from the GCVS catalogue were classified differently in our catalogue.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2010, 2010

ABSTRACT We present a method of determination of space debris detection possibility by the &q... more ABSTRACT We present a method of determination of space debris detection possibility by the "Pi of the Sky" telescopes, based on observations made during normal service. Main feature of objects orbiting Earth is its movement on celestial sphere, comparing to the stars. This movement diminishes measured brightnesses of these objects, and in consequence influences possibilities of satellite detection. The altitude of orbit decreases, the satellite should be brighter, but at the same time possibility of detection diminishes because of higher angular velocity in the sky. As preliminary results we show an estimations of both of these effects.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2011, 2011

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2011, 2011

... A. Majchera, M. Sokołowskia, T. Batscha, AJ Castro-Tiradob, H. Czyrkowskic, M. Ćwiokc, R. Dąb... more ... A. Majchera, M. Sokołowskia, T. Batscha, AJ Castro-Tiradob, H. Czyrkowskic, M. Ćwiokc, R. Dąbrowskic, M. Jelınekb, G. Kasprowiczd, A. Majczynaa, K ... We were very lucky: the burst occurred inside our cameras' field of view and we observed it before, during and after the burst. ...

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

Gamma-Ray Bursts (GRB) are short impulses of gamma radiation (time duration ranges from 0.1 to 10... more Gamma-Ray Bursts (GRB) are short impulses of gamma radiation (time duration ranges from 0.1 to 100 s) distributed almost isotropically across the sky. Most probably they arise during explosions or collisions of stars at cosmological distances. In this paper we discuss their origin, properties and current models. The methods of their observations will be also described. At the end short

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

The &... more The "Pi of the Sky" robotic telescope has been designed for monitoring of a significant fraction of the sky with good time resolution and range. The main goal of the "Pi of the Sky" detector is to look for short timescale optical transients arising from various astrophysical phenomena, mainly for optical counterparts of Gamma Ray Burst (GRB). System design, observations

Experimental Astronomy, 2009

AIP Conference Proceedings, 2009

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2012, 2012

ABSTRACT We analyse burst of MXB 1728-34 obtained by the RXTE PCA instrument during the observati... more ABSTRACT We analyse burst of MXB 1728-34 obtained by the RXTE PCA instrument during the observational period from 1995 to 2005. Each spectrum was integrated over 0.25 second and was fitted to the extensive grid of atmospheric models after background subtraction. Theoretical model spectra were calculated by the ATM code for various chemical compositions, effective temperatures from 107 K to 3×107 K and surface gravities from critical gravity up to log g = 15.0 (cgs units). As the result of the fitting procedure we obtained the surface redshift z and the surface gravity log g simultaneously for each trial set of parameters. Therefore, we are able to calculate mass and radius of the neutron star in MXB 1728-34. Many satisfactory fits were obtained for each chemical composition, but for models with iron abundance 100 times greater than the solar value fits were better than others. For this chemical composition we recommend that mass and radius of the neutron star is in the range: M = 0.103 - 1.564 Mʘ and R = 1.745 - 10.620 km.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

ABSTRACT We present the first few steps of creation the second edition of the variable stars cata... more ABSTRACT We present the first few steps of creation the second edition of the variable stars catalogue, based on the "Pi of the Sky" data, collected during two years 2006-2007. We have chosen - 3000 variable star candidates from about 1.5 million objects.

EAS Publications Series, 2013

ABSTRACT Pi of the Sky is a system of wide field-of-view robotic telescopes which search for shor... more ABSTRACT Pi of the Sky is a system of wide field-of-view robotic telescopes which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system is designed for autonomous operation, follows the predefined observing strategy and adopts it to the actual conditions. We describe the current status of telescopes located in Chile and Spain and prospects for future development.

ABSTRACT We present determinations of masses, radii and bolometric luminosities for DA white dwar... more ABSTRACT We present determinations of masses, radii and bolometric luminosities for DA white dwarfs observed for the ESO SN Ia Progenitor Survey. Masses and radii of 513 stars were determined from their effective temperatures and surface gravities, obtained by Koester et al. (2009 [6]). We have used a grid of theoretical mass‐radius relations for carbon and oxygen core stars with hydrogen envelopes derived by Panei et al. (2000 [10]).

We present model atmospheres and theoretical spectra for X-ray bursters. Our models include the e... more We present model atmospheres and theoretical spectra for X-ray bursters. Our models include the effects of Compton scattering on free electrons. The atmospheres have compositions that are mixtures of hydrogen, helium, and iron. For our models the ratio of color temperature, TcT_cTc, to effective temperature, TeffT_{eff}Teff, is in the range 1.2 - 1.8. This ratio depends on TeffT_{eff}Teff, surface gravity, and iron abundance. For fixed TeffT_{eff}Teff and surface gravity, models with non-zero iron abundance exhibit values of Tc/TeffT_c/T_{eff}Tc/Teff that are slightly lower than pure hydrogen-helium models.

We present a new catalogue of masses, radii and bolometric luminosities for hot DA white dwarfs o... more We present a new catalogue of masses, radii and bolometric luminosities for hot DA white dwarfs observed by the Sloan Digital Sky Survey (Data Release 4). Masses and radii of 7134 non-magnetic stars were determined from their observed effective temperatures Teff and surface gravities log g by the spectroscopic method. We have used here the grid of theoretical mass-radius relations for carbon-core stars with hydrogen-envelopes derived by Panei et al. (2000). Mass distribution of DA white dwarfs with Teff >= 12000 K has one maximum at M=0.549 M&sun;. However, we discovered the existence of the secondary maximum at about 0.393 M&sun; for hotter white dwarf stars. We also turn attention to low-mass white dwarfs (M

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2010, 2010

ABSTRACT We presented preliminary results for our catalogue of the variable stars from the 2006-2... more ABSTRACT We presented preliminary results for our catalogue of the variable stars from the 2006-2007 "Pi of the Sky" data. Our catalogue contains more than 1 000 variable stars of different type. The most numerous group in our catalogue are eclipsing variables (515) whereas pulsating variables are less numerous (292). Significant group consists stars classified simply as "variable" (180). For these stars we can not be able to determine more detailed type of the variability. Our classification was based on the shape of the light curve, as in the GCVS catalogue. However, some stars from the GCVS catalogue were classified differently in our catalogue.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2010, 2010

ABSTRACT We present a method of determination of space debris detection possibility by the &q... more ABSTRACT We present a method of determination of space debris detection possibility by the "Pi of the Sky" telescopes, based on observations made during normal service. Main feature of objects orbiting Earth is its movement on celestial sphere, comparing to the stars. This movement diminishes measured brightnesses of these objects, and in consequence influences possibilities of satellite detection. The altitude of orbit decreases, the satellite should be brighter, but at the same time possibility of detection diminishes because of higher angular velocity in the sky. As preliminary results we show an estimations of both of these effects.

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2011, 2011

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2011, 2011

... A. Majchera, M. Sokołowskia, T. Batscha, AJ Castro-Tiradob, H. Czyrkowskic, M. Ćwiokc, R. Dąb... more ... A. Majchera, M. Sokołowskia, T. Batscha, AJ Castro-Tiradob, H. Czyrkowskic, M. Ćwiokc, R. Dąbrowskic, M. Jelınekb, G. Kasprowiczd, A. Majczynaa, K ... We were very lucky: the burst occurred inside our cameras' field of view and we observed it before, during and after the burst. ...

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

Gamma-Ray Bursts (GRB) are short impulses of gamma radiation (time duration ranges from 0.1 to 10... more Gamma-Ray Bursts (GRB) are short impulses of gamma radiation (time duration ranges from 0.1 to 100 s) distributed almost isotropically across the sky. Most probably they arise during explosions or collisions of stars at cosmological distances. In this paper we discuss their origin, properties and current models. The methods of their observations will be also described. At the end short

Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2009, 2009

The &... more The "Pi of the Sky" robotic telescope has been designed for monitoring of a significant fraction of the sky with good time resolution and range. The main goal of the "Pi of the Sky" detector is to look for short timescale optical transients arising from various astrophysical phenomena, mainly for optical counterparts of Gamma Ray Burst (GRB). System design, observations

Experimental Astronomy, 2009