ar X iv : a st ro - p h / 98 12 05 0 v 1 2 D ec 1 99 8 VLBI Observations of the Galactic Center Source Sgr A * at 86 GHz and 215 GHz
نویسندگان
چکیده
We 1 summarize previous VLBI observations of Sgr A* at millimeter wavelengths and present new results from VLBI observations at 86 GHz and at 215 GHz. At 86 GHz the measured closure phase is close to zero, consistent with a point-like or symmetric structure of 190±30 µas size. At 215 GHz we have (for the first time) detected Sgr A* with a signal-to-noise ratio of 6. This yields a tentative size estimate of 50 ≤ θ ≤ 190 µas, which is larger than the scattering size of 20µas at this frequency. The intrinsic size of Sgr A* thus appears to be a few up to a few ten Schwarzschild radii (for a 2.6 · 10 6 M ⊙ black hole).
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