Letter to the Editor

HD 144432: A young triple system^⋆

¹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: amueller@mpia.de
² ISDC Data Centre for Astrophysics & Geneva Observatory, University of Geneva, chemin d’Ecogia 16, 1290 Versoix, Switzerland
³ Observatoire de Genève, University of Geneva, chemin des Maillettes 51, 1290 Sauverny, Switzerland
e-mail: andres.carmona@unige.ch
⁴ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching b. München, Germany

Received: 30 August 2011
Accepted: 7 October 2011

Abstract

We present new imaging and spectroscopic data of the young Herbig star HD 144432 A, which is a well-known binary star with a separation of 1.47″. High-resolution NIR imaging data obtained with NACO at the VLT reveal that HD 144432 B itself is a close binary pair with a separation of 0.1″. High-resolution optical spectra, acquired with FEROS at the 2.2m MPG/ESO telescope in La Silla, of the primary star and its co-moving companions are used to determine their main stellar parameters, such as effective temperature, surface gravity, radial velocity, and projected rotational velocity by fitting synthetic spectra to the observed stellar spectra. The two companions, HD 144432 B and HD 144432 C, are identified as low-mass T Tauri stars of spectral type K7V and M1V, respectively. From the position in the HRD, the triple system appears to be co-eval with a system age of 6 ± 3 Myr.