Near-Infrared Spectroscopy of HZ in Proto-Planetary Nebulae
We measured 2.1 - 2.3 mum spectra for a fairly complete sample of known proto-planetary nebulae (PPN) at declinations greater than -30degrees. This spectral range includes the H-2 emission lines 1-0 S(1), 1-0 S(0), 2-1 S(1), 2-1 S(2), and 3-2 S(3). We detected H2 emission from 16 of the 51 nebulae in our survey, including radiatively-excited H-2 from several non-bipolar PPN.
Kelly, D. M. and Hrivnak, Bruce J., "Near-Infrared Spectroscopy of HZ in Proto-Planetary Nebulae" (2003). Physics and Astronomy Faculty Publications. 109.