5 research outputs found
Adaptive Optics Integral Field Spectroscopy of the Young Stellar Objects in LkH_alpha 225
Progress in understanding the embedded stars in LkHa225 has been hampered by
their variability, making it hard to compare data taken at different times, and
by the limited resolution of the available data, which cannot probe the small
scales between the two stars. In an attempt to overcome these difficulties, we
present new near-infrared data on this object taken using the ALFA adaptive
optics system with the MPE 3D integral field spectrometer and the near-infrared
camera Omega-Cass. The stars themselves have K-band spectra which are dominated
by warm dust emission, analagous to class I-II for low mass YSOs, suggesting
that the stars are in a phase where they are still accreting matter. On the
other hand, the ridge of continuum emission between them is rather bluer,
suggestive of extincted and/or scattered stellar light rather than direct dust
emission. The compactness of the CO emission seen toward each star argues for
accretion disks (which can also account for much of the K-band veiling) rather
than a neutral wind. In contrast to other YSOs with CO emission, LkHa225 has no
detectable Br_gamma emission. Additionally there is no H_2 detected on the
northern star, although we do confirm that the strongest H_2 emission is on the
southern star, where we find it is excited primarily by thermal mechanisms. A
second knot of H_2 is observed to its northeast, with a velocity shift of
-75kms and a higher fraction of non-thermal emission. This is discussed with
reference to the H2O maser, the molecular outflow, and [S II] emission observed
between the stars.Comment: to appear in ApJ, April 2001. 18 pages, including 6 figure