Author: Narziev M., Institute of Astrophysics, Academy of Sciences of Tajikistan

Title:  Study of the Physico-Kinematic Properties of Meteoroids Based on Combined Radar and Optical Observations 

Abstracts: 

This report presents the results of a doctoral dissertation prepared by the author. The dissertation aims to investigate the complex physico-kinematic properties of meteoroids brighter than +5 magnitude based on the results of combined multi-station radio and optical (R-O) observations. 

During the research, the following results were achieved: 

• Equations of ionization were obtained, considering various forms of ablation;
• 8 radio-photographic (with spectrum obtained for bolide 770954) and 57 jointly registered radio-television (R-TV) meteors were identified based on observations at the GisAO;
• It was established that the velocity measured by the combined R-TV method is
  1.5-3 km/s greater than that measured by the radar method;
• Light curves and ionization curves were obtained, photometric and ionization masses of the same meteors were calculated, mechanisms of disintegration of R-O meteoroids were studied, and density and porosity of precise and sporadic meteoroids were determined;
• It was found that the ratio of luminosity intensity to linear electron density for meteors from 0^m to +8^m decreases more than tenfold with increasing velocity and decreasing atomic mass of the material (the latter based on laboratory modeling results);
• It was revealed that the intensity of luminosity and ionization in the first half of the R-O meteor array of different brightness ranges increases exponentially, while in the second half it decreases more smoothly;
• Based on 1100 experimental ionization curves obtained by the author, it was established that the heights of the mirror points are 0.4±0.8 km lower than the heights of maximum ionizations;
• A methodology for determining the physical characteristics of meteors observed from a single station was developed;
• Primary data processing was carried out, and orbits of monthly and annual radar observations of meteors obtained from four to five points at GisAO using a new radio direction-finding-time method were calculated, and a new Catalog of radiants, velocities, orbits, and atmospheric trajectory data of 8916 meteors brighter than +5^m was compiled, which is unparalleled globally and registered at the CMD of IAU;
• Analyses of Catalog materials revealed that radiants of meteors brighter than +5^m in the northern celestial hemisphere are almost uniformly distributed;
• 431 meteor streams and associations were identified from Catalog materials, about half of which were detected for the first time by radio method;
• Mass indices for daytime meteor streams η-Aquariids, o-Cetids, Piscids, ν-Piscids, and Arietids and nighttime δ-Aquariids, Quadrantids, Geminids, Northern and Southern δ-Aquariids, ι-Aquariids were determined.