Determination of bolometric albedo based on spectroscopic measurements for selected dust analogues and its impact on the change of cometary brightness during its outburst

Abstract

The paper presents the results of spectroscopic measurements for selected dust analogues, based on which change in cometary brightness was determined. In the first part of the article, we present the results of laboratory measurements of hemispherical albedo for selected dust analogues using a Cary 5000 spectrometer with an integrating sphere. In the case of this system and the tested samples, the obtained hemispherical albedo values ranged from 0.35 ± 0.07% to 41.58 ± 0.07%. The obtained measurement results were used to determine the bolometric albedo and geometric albedo. For the analogue consisting of charcoal, the Bond albedo was equal to AB(charcoal) = 2.15%, whereas the geometric albedo was equal to pv(charcoal) = 6.76%. The second part of the paper presents an analytical method allowing us to calculate the amplitude of the change of cometary brightness during the outburst. The calculations show that the upper value of the amplitude is 6.5 magnitudes, which is within the medium range amplitude of the outburst. Calculations have shown that as the bolometric albedo increases for a given agglomerate porosity, the temperature decreases, which determines a smaller sublimation flux, which translates into a larger change in the cometary brightness.