Comets and Nongravitational Forces. IV

Abstract

view Abstract Citations (58) References (28) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Comets and Nongravitational Forces. IV Marsden, B. G. ; Sekanina, Z. Abstract Orbital elements and nongravitational parameters are derived from observations at every apparition of the periodic comets Honda-Mrkos- , Faye, Tempel 2, Biela, Brorsen, and Tempel-Swift. For all except the first comet, the observations go back a century and more, although the last three comets have failed to reappear for some considerable time. The circumstances of the splitting of P/Biela are studied, and it is shown that the motion of the primary component was scarcely affected; it is also demonstrated that, if the primary still exists, it may pass only 0.05 A.U. from the Earth in November 1971. An up-to-date list of mass-loss rates from comets is presented. It is found that, while most of the reliable determinations indicate that the cometary nongravitational effects decrease with time, there are a few cases where the effects increase slightly. The former situation is discussed in terms of a nuclear core-mantle model, implying that these comets will eventually evolve into inert, asteroidal objects, while the nuclei of the other comets are interpreted as coreless, eventually to disappear completely (or almost completely). A list is given of seven erratic" comets known or suspected to have experienced large and relatively sudden anomalies in their motions. There is no conflict with observed phenomena when one interprets these anomalies in terms of collisions of coreless (snowball) comets with other objects, specifically the interplanetary boulders postulated by Harwit; it is also proposed that these boulders may themselves be of cometary origin. Publication: The Astronomical Journal Pub Date: December 1971 DOI: 10.1086/111232 Bibcode: 1971AJ.....76.1135M full text sources ADS |