A parallax distance and mass estimate for the transitional millisecond pulsar system J1023+0038

TL;DR

This study uses VLBA astrometry to measure the distance and motion of the transitional millisecond pulsar system J1023+0038, enabling a refined neutron star mass estimate and insights into its evolutionary state.

Contribution

The paper provides the first parallax-based distance measurement for J1023+0038, improving neutron star mass estimates and understanding of its kinematics.

Findings

Parallax of 0.731 mas measured with VLBA

Distance estimate of approximately 1368 parsecs

Neutron star mass estimated at 1.71 solar masses

Abstract

The recently discovered transitional millisecond pulsar system J1023+0038 exposes a crucial evolutionary phase of recycled neutron stars for multiwavelength study. The system, comprising the neutron star itself, its stellar companion, and the surrounding medium, is visible across the electromagnetic spectrum from the radio to X-ray/gamma-ray regimes and offers insight into the recycling phase of millisecond pulsar evolution. Here, we report on multiple-epoch astrometric observations with the Very Long Baseline Array (VLBA) which give a system parallax of 0.731 +/- 0.022 milliarcseconds (mas) and a proper motion of 17.98 +/- 0.05 mas/yr. By combining our results with previous optical observations, we are able to use the parallax distance of 1368+42-39 pc to estimate the mass of the pulsar as 1.71 +/- 0.16 solar masses, and we are also able to measure the 3D space velocity of the system as 126 +/- 5 km/s. Despite the precise nature of the VLBA measurements, the remaining ~3% distance uncertainty dominates the 0.16 solar mass error on our mass estimate.