Unknown sibling showers of comets C/1992 W1 (Ohshita) and C/1853 G1 (Schweizer)

Abstract

We present the results of modeling the meteoroids streams of two long-period comets, C/1992 W1 (Ohshita) and C/1853 G1 (Schweizer). The streams of both comets create at least two meteor showers in the Earth’s atmosphere.1. IntroductionThe relationships of minor meteor showers to comets with large aphelion distances have not been revealed as often as those associated to short-period comets. It especially concerns those cases when showers are caused by parts of the stream in which meteoroids move on orbits altered with regard to the orbit of their parent body.After being ejected from the comet, meteoroids are influenced by gravitational perturbations of planets and non-gravitational forces. This is why meteoroid streams often form filamentary structures. If more than a single filament passes through the Earth’s orbit, we observe several meteor showers associated with the same parent body. Their radiants often exhibit a symmetry in respect to the Earth’s apex (e.g. Fig. 1).2. The χ-Andromedids and January α-Ursae MajoridsWe modelled and studied the dynamical evolution of a meteoroid stream assumed to originate from the long-period comet C/1992 W1 (Ohshita) [1]. The theoretical stream approached the Earth’s orbit in six various filaments corresponding to six different meteor showers. We identified two of them in the IAU MDC Shower database [2] as the χ-Andromedids (#580) and, possibly, the January α-Ursae Majorids (#606), and found their real counterparts in the meteor databases [3, 4, 5], see Fig. 1. The other predicted showers have not been found among real meteors. Figure 1. The radiant positions of the modelled meteors associated to C/1992 W1 (black dots) and of their real counterparts (colored symbols – different video databases), shown in the Earth-apex-centered ecliptical coordinates.3. The γ-Aquilids and 52 HerculidsOur model of a theoretical stream of the comet C/1853 G1 (Schweizer) showed that two meteor showers may originate from this comet [6]. One of them corresponds to the γ-Aquilids (#531) and the other, though not certainly, to the 52 Herculids (#605). Both showers were found among real meteors in the databases. Possible consequences of the uncertainty of the cometary orbit were estimated by constructing models based on a set of cloned orbits (Fig. 2).Figure 2. The positions of the radiants in the models derived from the cloned orbits (black) and from the nominal orbit (red) of the C/1853 G1, shown in the Earth-apex-centered ecliptical coordinates.  AcknowledgementsThis work was supported by the Slovak Grant Agency for Science (VEGA), grant No. 2/0037/18, and by the Slovak Research and Development Agency under the contract No. APVV-16-0148.