Vol. 590
In section 7: Stellar structure and evolution

An M-dwarf star in the transition disk of Herbig HD142527. Physical parameters and orbital elements

by S. Lacour, B. Biller, A. Cheetham, et al. A&A 590, A90


The Herbig AeBe star HD 142527A hosts a transitional disk with the largest known gas-cleared gap (from 30 to 90 AU). The HD 142527 system is also unique in that the stellar companion's mass is 20 times smaller than that of the primary star. The low-mass companion may be responsible for both the gap and the dust trapping observed by ALMA at distances farthest from the primary. The authors observed the system with the NACO and GPI instruments using the aperture masking technique, and present the SEDs for HD 142527A and B from the R band up to the M band. They also derive the orbital motion of HD 142527B over a period of more than two years. They find that the B-component SED is compatible with a T = 3000 ± 100 K object to which a 1700 K black body environment (likely a circum-secondary disk) is added. From evolutionary models, they find that HD142527B has a mass of 0.13 ± 0.03 Mo, a radius of 0.90±0.15 Ro, while its age (1.0±1.0 Myr) is significantly lower than the age previously estimated for HD142527A. This adds another brick to the wall of growing evidence that a disagreement exists between ages derived from low-mass star models and from intermediate-mass star models. From a study of the orbital parameters, the authors conclude that despite its high eccentricity, HD142527B is probably not responsible for truncating the inner edge of the outer disk surrounding the A component.