  We present spectroscopic and photometric results of Nova V1280 Sco which was
discovered in outburst in early 2007 February. The large number of spectra
obtained of the object leads to one of the most extensive, near-infrared
spectral studies of a classical nova. The spectra evolve from a P-Cygni phase
to an emission-line phase and at a later stage is dominated by emission from
the dust that formed in this nova. A detailed model is computed to identify and
study characteristics of the spectral lines. Inferences from the model address
the vexing question of which novae have the ability to form dust. It is
demonstrated, and strikingly corroborated with observations, that the presence
of lines in the early spectra of low-ionization species like Na and Mg -
indicative of low temperature conditions - appear to be reliable indicators
that dust will form in the ejecta. It is theoretically expected that mass loss
during a nova outburst is a sustained process. Spectroscopic evidence for such
a sustained mass loss, obtained by tracing the evolution of a P-Cygni feature
in the Brackett gamma line, is presented here allowing a lower limit of 25-27
days to be set for the mass-loss duration. Photometric data recording the
nova's extended 12 day climb to peak brightness after discovery is used to
establish an early fireball expansion and also show that the ejection began
well before maximum brightness. The JHK light curves indicate the nova had a
fairly strong second outburst around 100 days after the first.
