Radiostars

ABDoradus

The radio stars ABDorB and ABDorA (= Rst137B) are the main components of the ABDoradus system. Both stars are doubles themselves (ABDorA / ABDorC and ABDorBa / ABDorBb) and frequently observed with astrometric instruments in the optical (HIPPARCOS), infrared (VLT) and radio (VLBI) wavelengths. From the combination of different astrometric data sets we have determined the orbit of ABDorC, the low-mass companion of ABDorA, and estimated its mass to be 0,090 ± 0,003 Msun. The mass of ABDorC is particularly interesting because this object is one of the few reference calibrators for stellar evolutionary models of young low-mass objects. Moreover, we also found evidence of ABDorA orbital motion around ABDorBa / Bb, which provides an upper limit to the mass of this pair of 0.4Msun and, therefore, a range for the total mass of the quadruple system (0.95-1.35Msun).

Precise determination of ABDorA/C and ABDorA/B orbits (Guirado et al. A&A, 446, 733, 2006).
Detection of ABDorC in the infrared wavelength (Close et al. Nature, 433, 286, 2005).
Astrometric detection of ABDorC from VLBI observations and HIPPARCOS data (Guirado et al. ApJ, 490, 835, 1997).
Download: Poster IAU Symposium No.248: "A Giant Step: from Milli- to Micro-arcsecond Astrometry"

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