We report infrared spectroscopy of the unusual eclipsing pre-main sequence object KH 15D , obtained using NIRSPEC on Keck II .
During eclipse , observations using low spectral resolution ( \lambda / \delta \lambda \sim 1000 ) reveal the presence of prominent molecular hydrogen emission in 5 lines near 2 ~ { } \mu m. The relative line strengths are consistent with thermal excitation at T \sim 2800 \pm 300 K .
Observations out of eclipse , at both low and high spectral resolution ( \lambda / \delta \lambda \sim 2 \times 10 ^ { 4 } ) , show reduced contrast with the stellar continuum .
The change in contrast for the strongest line , 1-0 S ( 1 ) , is consistent with an approximately constant emission line superposed on a variable stellar continuum .
Emission in the 1-0 S ( 1 ) line is observed to extend by \gtrsim 4 arc-sec both east and west of the stellar point spread function ( \gtrsim 3000 AU ) .
Observed at high spectral resolution , the velocity and intensity structure of the 1-0 S ( 1 ) profile are both asymmetric .
East of the stellar PSF ( by 1.1 - 2.3 arc-sec ) the emission is blueshifted ( -63 km sec ^ { -1 } ) , and has significantly greater intensity than the marginally redshifted component ( +2 km sec ^ { -1 } , \sim consistent with zero ) which dominates west of the stellar PSF .
The spatial extent of the emission , and the excitation temperature , suggest shock-excitation of ambient gas by a bipolar outflow from the star and/or disk .
However , it is difficult to account for the observed radial velocity unless the outflow axis is inclined significantly to the plane of the sky .