Aims. This study aims to better characterize this companion, which could help explain its impact on the peculiar geometry of the disk.
Method. We observed the source with VLT/SINFONI in H + K band in pupil-tracking mode. Data were post-processed with several algorithms based on angular differential imaging (ADI).
Results. HD 142527 B is conspicuously re-detected in most spectral channels, which enables us to extract the first medium-resolution spectrum of a low-mass companion within 0:001 from its central star. Fitting our spectrum with both template and synthetic spectra suggests that the companion is a young M2.5 1.0 star with an elective temperature of 3500 100 K, possibly surrounded with a hot (1700 K) circum-secondary environment. Pre-main sequence evolutionary tracks provide a mass estimate of 0.34 0.06 M, independent of the presence of a hot environment. However, the estimated stellar radius and age do depend on that assumption; we find a radius of 1:37 0:05 R (resp. 1.96 0.10 R) and an age of 1:8+1:2-0:5 Myr (resp. 0:75 0:25 Myr) in the case of the presence(resp. absence) of a hot environment contributing in H + K. Our new values for the mass and radius of the companion yield a mass accretion rate of 4.1–5.8 x 10-9 M yr-1 (2–3% that of the primary).
Conclusions. We have constrained the physical properties of HD 142527 B, thereby illustrating the potential for SINFONI+ADI tocharacterize faint close-in companions. The new spectral type makes HD 142527 B a twin of the well-known TW Hya T Tauri star,and the revision of its mass to higher values further supports its role in shaping the disk.
- Binaries: close
- Protoplanetary disks
- Stars: individual: HD 142527
- Stars: low-mass
- Stars: pre-main sequence