Binary Parameters for the Recurrent Nova T Coronae Borealis

TL;DR

This study refines the orbital and stellar parameters of the recurrent nova T Coronae Borealis using new spectroscopic data, confirming a nearly circular orbit and a massive white dwarf close to the Chandrasekhar limit.

Contribution

The paper provides updated, precise orbital parameters and stellar masses for T CrB, combining new spectra with literature data and applying maximum likelihood modeling.

Findings

Orbit is nearly circular with a period of ~227.55 days.

White dwarf mass is approximately 1.37 solar masses.

Secondary red giant mass is about 0.69 solar masses.

Abstract

T CrB is among the brightest novae. It is recurrent with outbursts happening approximately every 80 years. The next outburst is imminent, expected in 2025. The T CrB binary consists of an M4 III red giant (RG) secondary and a white dwarf (WD) primary. A time series of spectra of the RG was obtained between 2022 and 2024. Radial velocities (RVs) from these data were combined with literature RVs and an updated orbit computed. The orbit is circular to a high precision and has a period of 227.5494 +/- 0.0049 days for the circular solution. An eccentric solution yields an eccentricity of 0.0072 +/- 0.0026. Rotational line broadening of the RG was also measured. Binary parameters are derived by maximum likelihood modeling of the available observational data. The WD, in accord with other estimates for recurrent novae, is massive. Assuming the Gaia distance, the WD mass is 1.37 +/- 0.01 M sun with the M giant secondary mass 0.69 +0.02/-0.01 M sun. We discuss the evolution of this system and both paths to and limitations on further refining the values of the system parameters.