Characterising Young Visual M-dwarf Binaries with Near-Infrared Integral Field Spectra

TL;DR

This study uses near-infrared integral field spectroscopy to characterize seven young M-dwarf binary systems, providing spectral types, effective temperatures, and signs of youth, aiding future calibration of stellar evolutionary models.

Contribution

It offers the first resolved spectral classification and temperature estimates for these binaries, enhancing understanding of young low-mass star properties.

Findings

All targets show signs of youth and low surface gravity.

Spectral types and effective temperatures were determined for each component.

The systems serve as benchmarks for calibrating stellar evolutionary models.

Abstract

We present the results from an integral field spectroscopy study of seven close visual binary pairs of young M-dwarf multiple systems. The target systems are part of the astrometric monitoring AstraLux program, surveying hundreds of M-dwarf systems for multiplicity and obtaining astrometric epochs for orbital constraints. Our new VLT/SINFONI data provides resolved spectral type classification in the J, H and K bands for seven of these low-mass M-dwarf binaries, which we determine by comparing them to empirical templates and examining the strength of water absorption in the K-band. The medium resolution K-band spectra also allows us to derive effective temperatures for the individual components. All targets in the survey display several signs of youth, and some have kinematics similar to young moving groups, or low surface gravities which we determine from measuring equivalent widths of gravity sensitive alkali lines in the J-band. Resolved photometry from our targets is also compared with isochrones from theoretical evolutionary models, further implying young ages. Dynamical masses will be provided from ongoing monitoring of these systems, which can be seen as emblematic binary benchmarks that may be used to calibrate evolutionary models for low-mass stars in the future.