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NGC 7129 is a bright reflection nebula located in the molecular cloud complex near l=105.4, b=+9.9, about 1.15 kpc distant. Embedded within the reflection nebula is a young cluster dominated by a compact grouping of four early-type stars: BD+65 1638 (B3V), BD+65 1637 (B3e), SVS 13 (B5e), and LkH-alpha 234 (B8e). About 80 H-alpha emission sources brighter than V~23 are identified in the region, many of which are presumably T Tauri star members of the cluster. We also present deep (V~23), optical (VRI) photometry of a field centered on the reflection nebula and spectral types for more than 130 sources determined from low dispersion, optical spectroscopy. The narrow pre-main sequence evident in the color-magnitude diagram suggests that star formation was rapid and coeval. A median age of about 1.8 Myr is inferred for the H-alpha and literature-identified X-ray emission sources having established spectral types, using pre-main sequence evolutionary models. Our interpretation of the structure of the molecular cloud and the distribution of young stellar objects is that BD+65 1638 is primarily responsible for evacuating the blister-like cavity within the molecular cloud. LkH-alpha 234 and several embedded sources evident in near infrared adaptive optics imaging have formed recently within the ridge of compressed molecular gas. The compact cluster of low-mass stars formed concurrently with the early-type members, concentrated within a central radius of ~0.7 pc. Star formation is simultaneously occurring in a semi-circular arc some ~3 pc in radius that outlines remaining dense regions of molecular gas. High dispersion, optical spectra are presented for BD+65 1638, BD+65 1637, SVS 13, LkH-alpha 234, and V350 Cep. These spectra are discussed in the context of the circumstellar environments inferred for these stars.
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 proce
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We present a UBV I and H alpha photometric study of the young open cluster NGC 1893 in the H II region W8 (IC 410 or Sh 2-236). A total of 65 early-type members are selected from photometric diagrams. A mean reddening of the stars is <E(B-V)> = 0.563
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