0000000000536092
AUTHOR
Emanuele Tognelli
Young, active radio stars in the AB Doradus moving group
Context. Precise determination of stellar masses is necessary to test the validity of pre-main-sequence (PMS) stellar evolutionary models, whose predictions are in disagreement with measurements for masses below 1.2 M. To improve such a test, and based on our previous studies, we selected the AB Doradus moving group (AB Dor-MG) as the best-suited association on which to apply radio-based high-precision astrometric techniques to study binary systems. Aims. We seek to determine precise estimates of the masses of a set of stars belonging to the AB Dor-MG using radio and infrared observations. Methods. We observed in phase-reference mode with the Very Large Array (VLA) at 5 GHz and with the Eur…
Evidence of a substellar companion to AB Dor C
Studies of fundamental parameters of very low-mass objects are indispensable to provide tests of stellar evolution models that are used to derive theoretical masses of brown dwarfs and planets. However, only objects with dynamically determined masses and precise photometry can effectively evaluate the predictions of stellar models. AB Dor C (0.090 solar masses) has become a prime benchmark for calibration of theoretical evolutionary models of low-mass young stars. One of the ambiguities remaining in AB Dor C is the possible binary nature of this star. We observed AB Dor C with the VLTI/AMBER instrument in low-resolution mode at the J, H and K bands. The interferometric observables at the K-…
The AB Doradus system revisited: The dynamical mass of AB Dor A/C
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 …