The low mass companion of HIP 45314 (HR 3672)

TL;DR

This paper reports the discovery and characterization of a very low-mass companion to the star HR 3672, confirming its companionship through multi-epoch observations and estimating its properties using models.

Contribution

It introduces a new method for astrometric calibration and reanalyzes the star's cluster membership, alongside characterizing the low-mass companion.

Findings

Companion confirmed as bound object with >4 sigma confidence.

Estimated companion mass between 0.2 and 0.5 solar masses.

No additional companions detected within 13 arcseconds down to 0.03 solar masses.

Abstract

We report the discovery of a very low-mass companion to HIP 45314 (HR 3672) located about 2.7 arcsec north-west of HR 3672 A. With four years of epoch difference between the two observations obtained with the Very Large Telescope we can reject by more than 4 sigma that B would be a non-moving background object unrelated to A. HR 3672 A is a B 7-8 main sequence star with an age of 140 \pm 80 Myr and from the magnitude difference between HR 3672 A and B and the 2MASS magnitudes, we can estimate the magnitude of HR 3672 B (K_{s}=12.42 \pm 0.28 mag) and then, for age and distance of the primary star, using models, its luminosity and mass (0.2-0.5 M_sun). We present a reanalysis of the probable membership of HR 3672 A to the Platais 9 cluster, and introduce a new method for astrometric calibration of data without dedicated calibration images. In the deepest available image (co-add of all epochs) no additional companion candidates within 13 arcsec were detected down to 0.03 M_sun.