Characterizing HR3549B using SPHERE

TL;DR

This study uses SPHERE instrument data to characterize the low-mass companion HR3549B, determining its properties, orbit, and spectral type, thereby enhancing understanding of substellar companions around A-type stars.

Contribution

First detailed characterization of HR3549B using SPHERE, providing photometry, astrometry, spectral type, and orbital constraints for this substellar companion.

Findings

Companion confirmed as a bound object.

Estimated mass of 40-50 Jupiter masses.

Spectral type between M9 and L0.

Abstract

Aims. In this work, we characterize the low mass companion of the A0 field star HR3549. Methods. We observed HR3549AB in imaging mode with the the NIR branch (IFS and IRDIS) of SPHERE@VLT, with IFS in YJ mode and IRDIS in the H band. We also acquired a medium resolution spectrum with the IRDIS long slit spectroscopy mode. The data were reduced using the dedicated SPHERE GTO pipeline, purposely designed for this instrument. We employed algorithms such as PCA and TLOCI to reduce the speckle noise. Results. The companion was clearly visible both with IRDIS and IFS.We obtained photometry in four different bands as well as the astrometric position for the companion. Based on our astrometry, we confirm that it is a bound object and put constraints on its orbit. Although several uncertainties are still present, we estimate an age of ~100-150 Myr for this system, yielding a most probable mass for the companion of 40-50MJup and T_eff ~300-2400 K. Comparing with template spectra points to a spectral type between M9 and L0 for the companion, commensurate with its position on the color-magnitude diagram.