* Astronomy

Title: A Keplerian gaseous disk around the B0 star R Mon
Authors: A. Fuente, T. Alonso-Albi, R. Bachiller, A. Natta, L. Testi, R. Neri, P. Planesas

Researchers present high-angular resolution observations of the circumstellar disk around the massive Herbig Be star R Mon (M~8 Msun) in the continuum at 2.7mm and 1.3mm and the CO 1->0 and 2->1 rotational lines. Based on the new 1.3mm continuum image they estimate a disk mass (gas+dust) of 0.007 solar masses and an outer radius of <150 AU. The researchers CO images are consistent with the existence of a Keplerian rotating gaseous disk around this star. Up to our knowledge, this is the most clear evidence for the existence of Keplerian disks around massive stars reported thus far.
The mass and physical characteristics of this disk are similar to those of the more evolved T Tauri stars and indicate a shorter timescale for the evolution and dispersal of circumstellar disks around massive stars which lose most of their mass before the star becomes visible.

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R Monocerotis (NGC2261), is a stellar infrared source and nebula in the constellation Monoceros (Greek: Unicorn). The star, one of the class of dwarf stars called T Tauri variables, is immersed in a cloud of matter that changes in brightness erratically, varying between magnitude 10 to 12, reflecting or re-radiating energy from the star.