Absolute Dimensions of the Interferometric Binary HD 174881: A Test of Stellar Evolution Models for Evolved Stars

TL;DR

This study precisely measures the physical properties of the binary star HD 174881 using interferometry and spectroscopy, providing critical data to test and validate stellar evolution models for evolved stars.

Contribution

It offers the first detailed absolute measurements of masses, radii, temperatures, and luminosities for this binary, enabling direct comparison with stellar evolution models.

Findings

Good agreement with MIST and PARSEC models at near-solar composition.

Derived ages of 255-273 million years for the system.

Detected infrared excess indicating additional circumstellar material.

Abstract

We report high-resolution spectroscopic monitoring and long-baseline interferometric observations with the PTI of the 215-day binary system HD 174881 (K1 II-III), composed of two giant stars. The system is spatially resolved with the PTI, as well as in archival measurements with the CHARA Array. Our analysis of these observations, along with an analysis of the spectral energy distribution, have allowed us to infer accurate values for the absolute masses ($3.367^{+0.045}_{-0.041} M_{\odot}$ and $3.476^{+0.043}_{-0.043} M_{\odot}$), radii ($34.0 \pm 1.3 R_{\odot}$ and $22.7 \pm 1.8 R_{\odot}$), effective temperatures ($4620 \pm 100$ K and $4880 \pm 150$ K), and bolometric luminosities of both components, as well as other properties including the orbital parallax (distance). These provide valuable tests of stellar evolution models for evolved stars, which are still relatively uncommon compared to the situation for main-sequence stars. We find generally good agreement of all of these properties of HD 174881 with two sets of recent models (MIST, and PARSEC) at compositions near solar, for ages of 255-273 Myr. We also find evidence of an infrared excess, based largely on the flux measurements from IRAS at 60 and 100 microns.