  The reflection nebula NGC 7129 has long been known to be a site of recent
star formation as evidenced, e.g., by the presence of deeply embedded
protostars and HH objects. However, studies of the stellar population produced
in the star formation process have remained rudimentary. At a presumed age of
~3 Myr, NGC7129 is in the critical range where disks around young stars
disappear. We make use of Chandra X-ray and Spitzer and 2MASS IR imaging
observations to identify the pre-main sequence stars in NGC7129. We define a
sample of Young Stellar Objects based on color-color diagrams composed from IR
photometry between 1.6 and 8 mu, from 2MASS and Spitzer, and based on X-ray
detected sources from a Chandra observation. This sample is composed of 26
Class II and 25 Class III candidates. The sample is estimated to be complete
down to ~ 0.5 solar masses. The most restricted and least biased sub-sample of
pre-main sequence stars is composed of lightly absorbed (A_V < 5 mag) stars in
the cluster core. This sample comprises 7 Class II and 14 Class III sources, it
has a disk fraction of 33^{+24}_{-19} %, and a median X-ray luminosity of log
(L_x) [erg/s] = 30.3. Despite the various uncertainties related to the sample
selection, absorption, mass distribution, distance and, consequently, the
computation of disk fraction and X-ray luminosities, the data yield consistent
results. In particular, we confirm the age of ~3 Myr for the NGC7129 cluster.
The derived disk fraction is similar to that of sigma Orionis, smaller than
that of Cha I (~2 Myr), and larger than that of Upper Sco (5 Myr). The X-ray
luminosity function is similar to that of NGC 2264 (2 Myr) but fainter than
that of the Orion Nebula Cluster (1 Myr).
