Radial migration of the Sun in the Milky Way: a statistical study

Abstract

The determination of the birth radius of the Sun is important to understand the evolution and consequent disruption of the Sun's birth cluster in the Galaxy. Motivated by this fact, we study the motion of the Sun in the Milky Way during the last 4.6 Gyr in order to find its birth radius. We carried out orbit integrations backward in time using an analytical model of the Galaxy which includes the contribution of spiral arms and a central bar. We took into account the uncertainty in the parameters of the Milky Way potential as well as the uncertainty in the present day position and velocity of the Sun. We find that in general the Sun has not migrated from its birth place to its current position in the Galaxy (R ). However, significant radial migration of the Sun is possible when: 1) The 2 : 1 Outer Lindblad resonance of the bar is separated from the corrotation resonance of spiral arms by a distance ∼ 1 kpc. 2) When these two resonances are at the same Galactocentric position and further than the solar radius. In both cases the migration of the Sun is from outer regions of the Galactic disk to R , placing the Sun's birth radius at around 11 kpc. We find that in general it is unlikely that the Sun has migrated significantly from the inner regions of the Galactic disk to R .

26Al kinematics: superbubbles following the spiral arms?

“…But co-rotation in the Galaxy is unfortunately too far out (8.4−12 kpc, e.g., Martínez-Barbosa et al 2015) to check for direction reversals in the data set of Paper I. At such galactocentric distances, individual 26 Al-emission regions are only a few, they are faint, and they are not associated with spiral arms.…”

Quest for the lost siblings of the Sun

“…We adopted the same Galactic model as Martínez-Barbosa et al (2015) where the axisymmetric part of the Galaxy is modelled by using the potential of Allen & Santillan (1991), which consists of a bulge, disk, and a dark matter halo. The parameters that describe the axisymmetric component of the Milky Way are listed in Table 9.…”

The solar siblings in the Gaia era

“…The bar and spiral arms are non transient structures that rotate as rigid bodies with different pattern speeds. The Galactic parameters used in the simulations are taken from Martínez-Barbosa et al (2015).…”

“…By using this technique, Martínez-Barbosa et al (2015) found the distribution of possible positions and velocities of the Sun at its birth (P (R b ), P (V b )). Given that for most of the Galactic parameters, (P (R b )) is peaked around 9 kpc, we assume initially for the Sun's birth cluster r cm = 9 kpc.…”

“…We used the huayno code (Pelupessy et al 2012) to compute the internal gravitational force in the Sun's birth cluster. To compute the force due to the external Galactic potential, we use a high-order Rotating bridge (Martínez-Barbosa et al 2015). The stellar evolution effects were modelled with the seba code (Portegies Zwart & Verbunt 1996;Toonen et al 2012).…”