Abstract Details
| Name: Goldy Ahuja Affiliation: Physical Research Laboratory, Ahmedabad Conference ID: ASI2025_382 Title : Estimating the Nuclear Size of Long-Period Comets Authors and Co-Authors : Goldy Ahuja 1, 2, K. Aravind 1, 3, Shashikiran Ganesh 1, Devendra K. Sahu 4, T. Sivarani 4 Abstract Type : Poster Abstract Category : Sun, Solar System, Exoplanets, and Astrobiology Abstract : Comets, composed of volatile ice and dust, are found in the different reservoirs far from the Sun. As these bodies come close to the Sun, their volatile surfaces start sublimating, forming an atmosphere of gas and dust known as the cometary coma. The size of the visible cometary coma is of the order of 10^4 km. The brightness of the coma presents a significant challenge in observing the nucleus. In the case of asteroids, R-band photometry has been used to estimate their radii. This technique is also beneficial for calculating the size of short-period comets when they are at a large distance from the Sun (when they do not have a well-developed coma). The long-period comets, which spend a small percentage of their orbital period time in the inner solar system, usually have a significant amount of volatiles, which can show or cause activity at distances larger than 5 AU, resulting in a coma. Hence, it is difficult to calculate the nuclear magnitude of these comets. In this poster, we will explain the various methods used for estimating the nuclear size of cometary bodies. One is to use the brightness function and extrapolate the magnitudes to a zero pixel to get the nuclear radius of a comet. Another method uses non-gravitational forces like the Yarkovsky effect, which is responsible for the non-gravitational acceleration. This non-gravitational acceleration is related to the radius of the comet. We applied these methods to get the radius of four long-period comets, i.e., C/2020 V2, C/2019 L3, C/2022 E3 and C/2023 A3. These long-period comets were observed from the Faint Object Camera (FOC) instrument mounted on the 2.5 m PRL telescope and the HFOSC instrument mounted on the 2 m Himalayan Chandra Telescope (HCT). |