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Szabolcs Barcza

Publications and source records attributed to Szabolcs Barcza.

4 recordsLinked to original sources
arXiv2017

Fundamental parameters of RR Lyrae stars from multicolour photometry and Kurucz atmospheric models. I. Theory and practical implementation

A photometric calibration of Kurucz static model atmospheres is used to obtain parameters of RR Lyrae stars: variation of stellar angular radius $\vartheta$, effective temperature $T_{\rm e}$, and gravity $g_{\rm e}$ as a function of phase, interstellar reddening $E(B-V)$ toward the star, and atmospheric metallicity $M$. Photometric and hydrodynamic conditions are given to find the phases of pulsation when the quasi-static atmosphere approximation (QSAA) can be applied. The QSAA is generalized to a non-uniformly moving spherical atmosphere, and the distance $d$, mass ${\cal M}$, and atmospheric motion are derived from the laws of mass and momentum conservation. To demonstrate the efficiency of the method, the $UBV(RI)_C$ photometry of SU Dra was used to derive the following parameters: $[M]=-1.60\pm .10$ dex, $E(B-V)=0.015\pm .010$, $d=663\pm 67$ pc, ${\cal M}=(0.68\pm .03){\cal M}_\odot$, equilibrium luminosity, $L_{\rm eq}=45.9\pm 9.3L_\odot$, $T_{\rm eq}=6813\pm 20$ K.

astro-ph.SR↗
arXiv2016

Greenhouse effect from the point of view of radiative transfer

Radiative power balance of a planet in the solar system is delineated. The terrestrial powers are transformed to average global flux in an effective atmospheric column (EAC) approximation, its components are delineated. The estimated and measured secular changes of the average global flux are compared to the fluxes derived from the Stefan-Boltzmann law using the observed global annual temperatures in the decades between 1880 and 2010. The conclusion of this procedure is that the radiative contribution of the greenhouse gas ${\rm CO}_2$ is some $21\pm 7$~\% to the observed global warming from the end of the XIXth century excluding the feedback mechanisms playing determining role in the climate system. Stationary radiative flux transfer is treated in an air column as a function of the column density of the absorbent. Upper and lower limit of radiative forcing is given by assuming true absorption and coherent scatter of the monochromatic radiation. An integral formula is given for the outgoing long wave radiation (OLR) as a function of column density of the components of greenhouse gases.

astro-ph.EP↗
arXiv2010

Fundamental parameters of RR Lyrae stars from multicolour photometry and Kurucz atmospheric models. I. Theory and practical implementation

A photometric calibration of Kurucz static model atmospheres is used to obtain the following parameters of RR Lyrae stars: variation of stellar angular radius $\vartheta$, effective temperature $T_{\rm e}$, gravity $g_{\rm e}$ as a function of phase, interstellar reddening $E(B-V)$ towards the star and atmospheric metallicity $M$. Photometric and hydrodynamic conditions are given to find the phases of pulsation when the quasi-static atmosphere approximation (QSAA) can be applied. The QSAA is generalized to a non-uniformly moving spherical atmosphere, and the distance $d$, mass ${\cal M}$ and atmospheric motion are derived from the laws of mass and momentum conservation. To demonstrate the efficiency of the method, the $UBV(RI)_C$ photometry of SU Dra was used to derive the following parameters: $[M]=-1.60\pm .10$~dex, $E(B-V)=0.015\pm .010$, $d=663\pm 67$~pc, ${\cal M}=(0.68\pm .03){\cal M}_\odot$, equilibrium luminosity $L_{\rm eq}=45.9\pm 9.3L_\odot$ and $T_{\rm eq}=6813\pm 20$~K.

astro-ph.SR↗