The multiplicity of exoplanet host stars - New low-mass stellar companions of the exoplanet host stars HD125612 and HD212301

TL;DR

This study reports the discovery of two new stellar companions to exoplanet host stars, expanding the known multiplicity rate and providing insights into the stellar environments of exoplanets.

Contribution

The paper presents new direct imaging detections of wide stellar companions to exoplanet host stars HD125612 and HD212301, adding to the known multiplicity statistics.

Findings

Discovered a wide M4 dwarf companion to HD125612.

Found a close M3 dwarf companion to HD212301.

The multiplicity rate of exoplanet host stars is approximately 17%.

Abstract

Aims: We present new results from our ongoing multiplicity study of exoplanet host stars, carried out with SofI/NTT. We provide the most recent list of confirmed binary and triple star systems that harbor exoplanets. Methods: We use direct imaging to identify wide stellar and substellar companions as co-moving objects to the observed exoplanet host stars, whose masses and spectral types are determined with follow-up photometry and spectroscopy. Results: We found two new co-moving companions of the exoplanet host stars HD125612 and HD212301. HD125612B is a wide M4 dwarf (0.18 Msun) companion of the exoplanet host star HD125612, located about 1.5 arcmin (~4750 AU of projected separation) south-east of its primary. In contrast, HD212301B is a close M3 dwarf (0.35 Msun), which is found about 4.4 arcsec (~230 AU of projected separation) north-west of its primary. Conclusions: The binaries HD125612AB and HD212301AB are new members in the continuously growing list of exoplanet host star systems of which 43 are presently known. Hence, the multiplicity rate of exoplanet host stars is about 17%. Based on observations obtained on La Silla in ESO programs 079.C-0099(A), 080.C-0312(A)