Chapter

The AB Doradus System Revisited: The Dynamical Mass of AB Dor A

DOI: 10.1007/978-3-642-11250-8_13

ABSTRACT We report new radio interferometric observations of the quadruple pre-main-sequence (PMS) system ABD oradus. From these observations,
combined with existing VLT near-infrared relative astrometry, we have refined the estimates of the dynamical masses of the
system. In particular, we find component masses of 0.86 ± 0.09M⊙ and 0.090 ± 0.003M⊙ for ABD or A and ABD or C, respectively. These dynamical masses, coupled with temperatures and luminosities, allow for comparison
with theoretical stellar models. The case of ABDorC, in terms of calibration of evolutionary models of low-mass young stars
has been widely reported in previous studies. In this contribution, we compare the measured properties of ABDorA with several
solar-composition models for PMS stars. The models used in this comparison predict the dynamical mass to within the quoted
uncertainties.

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    ABSTRACT: We present an astrometric analysis of the binary systems AB Dor A /AB Dor C and AB Dor Ba /AB Dor Bb. These two systems of well-known late-type stars are gravitationally associated and they constitute the quadruple AB Doradus system. From the astrometric data available at different wavelengths, we report: (i) a determination of the orbit of AB Dor C, the very low mass companion to AB Dor A, which confirms the mass estimate of 0.090 $M_\odot$ reported in previous works; (ii) a measurement of the parallax of AB Dor Ba, which unambiguously confirms the long-suspected physical association between this star and AB Dor A; and (iii) evidence of orbital motion of AB Dor Ba  around AB Dor A, which places an upper bound of 0.4 $M_\odot$ on the mass of the pair AB Dor Ba /AB Dor Bb  (50% probability). Further astrometric monitoring of the system at all possible wavelengths would determine with extraordinary precision the dynamical mass of its four components.
    Astronomy and Astrophysics 02/2006; · 5.08 Impact Factor