Tracing Stellar Close Encounters with Our Sun from GAIA DR2, LAMOST DR4, and RAVE DR5 Catalogues

Abstract

Our Sun is surrounded by the Oort Cloud (in radius 0.5 pc) which can be perturbed by various external factors. One of those is the stellar close encounter with our Sun. This kind of perturbation can induce the cometary showers in our Solar System. In this work, we attempt to make numerical simulations to trace the orbit of stars which close encounter with our Sun in the cases of Milky Way’s axisymmetric only and with non-axisymmetric potentials. We have 306 selected solar neighborhood stars from GAIA DR2, LAMOST DR4, and RAVE DR5 which have highly precise kinematics. In this work, we find a few stars that have counter parameter (dm ) less than or equal to 2 pc in both of past and future close encounters with the Sun. We also find a few stars (ID 283, 290, 297, 298) even with dm ≤ 0.5 pc within their errors, for past close encounters at time tm ≥ 0.5 Myr ago. These stars should have perturbed the Oort Cloud’s stability long time ago. Furthermore, we find a few stars (ID 293, 299, 300) with dm ≤ 1 pc within their errors, at tm > 0.6 Myr for future close encounters. Besides that,cadding non-axisymmetric component of Milky Way does not change the results. This suggests that the non-axisymmetric component of Milky Way potential has small effect in perturbing the orbital motion of stars for short timescale. That’s why the values of dm are relatively similar within their errors, for both cases of the Milky Way potential.

Analysis of Close Stellar Encounters with the Solar System

“…Our method in agreement with the linear one, yields a completely different result, t min = −0.620 ± 0.116 Myr and d min = 0.299 ± 0.096 pc. Here, we see poor agreement with the results from Darma et al (2019). Erroneous encounter parameters for this star are apparently given in Darma et al (2019).…”

“…Here, we see poor agreement with the results from Darma et al (2019). Erroneous encounter parameters for this star are apparently given in Darma et al (2019).…”

“…The encounter parameters for other common stars are not distinguished by good agreement. We trust our results more, while the discrepancies are apparently related to the errors or misprints in Darma et al (2019).…”

“…The encounter parameters for two stars from the list by Darma et al (2019) are of interest. For example, for the star Gaia DR2 52952724810126208 the following estimates were found by the third method, in agreement with the linear one: t min = −0.55 ± 0.06 Myr and d min = 0.21 ± 0.09 pc, while for the star Gaia DR2 3130033734235815424 t min = −0.62 ± 0.12 Myr and d min = 0.30 ± 0.10 pc have been obtained for the first time.…”

“…The following ones are commonly applied: (i) the linear method, (ii) the epicyclic approximation, or (iii) using an appropriate model Galactic gravitational potential. Large (more than 1 pc) discrepancies between the results of an analysis of the encounter parameters for ALS 9243 (Wysoczańska et al 2020) and several more stars from Darma et al (2019) that we got by applying various approaches served as a stimulus for writing this paper.…”