Improved age constraints for the AB Doradus quadruple system The binary nature of AB Doradus B

• Published in: Astronomy and astrophysics (Berlin) Vol. 462; no. 2; pp. 615 - 620
• Main Authors: Janson, M., Brandner, W., Lenzen, R., Close, L., Nielsen, E., Hartung, M., Henning, T., Bouy, H.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.02.2007
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; stars: individual: AB Doradus; Isochrone; Low-mass stars; Brown dwarf stars; Close binary stars; binaries: visual; stars: fundamental parameters; Visual binary stars; stars: low-mass, brown dwarfs; Age; Photometry; Astrometry
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20066208

We present resolved NACO photometry of the close binary AB Dor B in H-and K s-band. AB Dor B is itself known to be a wide binary companion to AB Dor A, which in turn has a very low-mass close companion named AB Dor C. These four known components make up the young and dynamically interesting system AB Dor, which will likely become a benchmark system for calibrating theoretical pre-main sequence evolutionary mass tracks for low- mass stars. However, for this purpose the actual age has to be known, and this subject has been a matter of discussion in the recent scientific literature. We compare our resolved photometry of AB Dor Ba and Bb with theoretical and empirical isochrones in order to constrain the age of the system. This leads to an age estimate of about 50 to 100 Myr. We discuss the implications of such an age range for the case of AB Dor C, and compare with other results in the literature.