Characterization of low-mass companion HD 142527 B
Context. The circumstellar disk of the Herbig Fe star HD 142527 is host to several remarkable features including a warped inner disk, a 120 au-wide annular gap, a prominent dust trap and several spiral arms. A low-mass companion, HD 142527 B, was also found orbiting the primary star at ~14 au. 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.″1 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 effective 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_(-0.5)^(+1.2) 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 4.1–5.8×10^(−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 to characterize 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.
© 2018 ESO. Article published by EDP Sciences. Received 1 August 2016; Accepted 12 June 2018; Published online 18 September 2018. Based on observations made with ESO Telescopes at the Paranal Observatory under program ID 084.C-0952 and 093.C-0526. We acknowledge the anonymous referee for his/her constructive comments. We are grateful to the VLT/SINFONI telescope staff (Kora Muzic and Ivan Aranda) for their precious help during the observing run. We thank Mickaël Bonnefoy, Jackie Faherty, Gregory Herczeg, Sylvestre Lacour and Gerrit van der Plas for useful discussions. We are also thankful to Ignacio Mendigutía for sharing the X-shooter spectrum of HD 142527. VC acknowledges support from CONICYT through CONICYT-PCHA/Doctorado Nacional/2016-21161112. VC and SC acknowledge support by the Millennium Science Initiative (Chilean Ministry of Economy), through grant RC130007. VC, OA, CGG and OW acknowledge support from the European Research Council under the European Union's Seventh Framework Program (ERC Grant Agreement n. 337569) and from the French Community of Belgium through an ARC grant for Concerted Research Action. AZ acknowledges support from the CONICYT + PAI/ Convocatoria nacional subvención a la instalación en la academia, convocatoria 2017 + Folio PAI77170087 This research has benefitted from the SpeX Prism Library (and/or SpeX Prism Library Analysis Toolkit), maintained by Adam Burgasser at http://www.browndwarfs.org/spexprism.
Published - aa29454-16.pdf
Accepted Version - 1806.04792.pdf