Open Clusters ASCC21 as a Probable Birthplace of the Neutron Star Geminga

TL;DR

This study traces the past trajectory of the neutron star Geminga to identify its probable birthplace, finding that the open cluster ASCC21 is the most likely origin within the OB association OriOB1a, based on orbital integration and simulations.

Contribution

It introduces a method of integrating epicyclic orbits with error analysis to identify the birthplace of neutron stars, specifically linking Geminga to open cluster ASCC21.

Findings

Geminga likely originated from open cluster ASCC21.

Close encounters within 10 pc occurred about 0.52 Myr ago.

Trajectory passes near lambda Ori, consistent with pulsar age.

Abstract

We analyze the encounters of the neutron star (pulsar) Geminga with open star clusters in the OB association OriOB1a through the integration of epicyclic orbits into the past by taking into account the errors in the data. The open cluster ASCC21 is shown to be the most probable birthplace of either a single progenitor star for the Geminga pulsar or a binary progenitor system that subsequently broke up. Monte Carlo simulations of Geminga--ASCC21 encounters with the pulsar radial velocity Vr =-100+-50 km/s have shown that close encounters could occur between them within <= 10 pc at about t=-0.52 Myr. In addition, the trajectory of the neutron star Geminga passes at a distance about 25 pc from the center of the compact OB association lambda Ori at about t=-0.39 Myr, which is close to the age of the pulsar estimated from its timing.