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

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 (d_m) 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 d_m ≤ 0.5 pc within their errors, for past close encounters at time t_m ≥ 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 d_m ≤ 1 pc within their errors, at t_m > 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 d_m are relatively similar within their errors, for both cases of the Milky Way potential.