Separated Fringe Packet Observations with the CHARA Array III. The Very High Eccentricity Binary HR 7345

TL;DR

This study combines visual and spectroscopic data over eleven years to precisely determine the orbit, masses, and parallax of the highly eccentric binary star HR 7345 using the CHARA Array and the SFP method.

Contribution

It provides the first detailed orbit and component masses for HR 7345, demonstrating the effectiveness of the SFP method for high-eccentricity binaries with long periods.

Findings

Orbital period of 331.609 days with high precision.

Component masses nearly equal at ~0.93 solar masses.

High eccentricity of 0.9322 makes the system one of the most eccentric known.

Abstract

After an eleven year observing campaign, we present the combined visual{spectroscopic orbit of the formerly unremarkable bright star HR 7345 (HD 181655, HIP 94981, GJ 754.2). Using the Separated Fringe Packet (SFP) method with the CHARA Array, we were able to determine a difficult to complete orbital period of 331.609 +/- 0.004 days. The 11 month period causes the system to be hidden from interferometric view behind the Sun for 3 years at a time. Due to the high eccentricity orbit of about 90% of a year, after 2018 January the periastron phase will not be observable again until late 2021. Hindered by its extremely high eccentricity of 0.9322 +/- 0.0001, the double-lined spectroscopic phase of HR 7345 is observable for 15 days. Such a high eccentricity for HR 7345 places it among the most eccentric systems in catalogs of both visual and spectroscopic orbits. For this system we determine nearly identical component masses of 0.941 +/- 0.076 Msun and 0.926 +/- 0.075 Msun as well as an orbital parallax of 41.08 +/- 0.77 mas.