An Infrared Jet from a High-Mass Young Star
Fuller G.A., Zijlstra A.A., Williams S. J, 2001, ApJ (Letters),
555, L125
Abstract
Jets are a direct consequence of accretion in the inner regions of
circumstellar disks. They trace the structure of the accretion disk and,
indirectly, the star formation mechanism. Here we report on the
discovery of a near-infrared jet from a young B1 star, one of the most
luminous young stars known to exhibit such a structure. The jet is seen
in L' images of IRAS 18556+0136 in the G35.2-0.74N region; a significant
fraction of the emission is due to Brα line emission. At shorter
wavelengths, the jet is obscured: the colors of the bipolar nebula are
consistent with 25 mag visual extinctions to the near lobe and 40 mag to
the far lobe. A previously detected radio continuum source and an
elongated clump of OH maser spots coincide with a break in the jet. This
is interpreted as the location of the circumstellar disk surrounding the
embedded young star. A lower limit of ~170 mag is derived for the
extinction to the exciting source. This provides an estimate of 0.15
Msolar for the mass of the circumstellar disk within ~1500 AU
of the central source. Emission knots on either side of a second, weaker
radio continuum source offset ~3 arcsec from the jet source suggests the
presence of a second outflow source in the region. The lack of known
jets in high-mass protostars, in contrast to their prevalence among
low-mass systems, points to a difference in the star formation process,
e.g., mergers. The jet from this B1 star suggests that the mechanisms
that form low-mass stars can operate up to at least 10 Msolar
stars.
paper (pdf, 110 kb)