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The Pre-Main-Sequence Population of L988
L988 is a large (~0.5d×0.7d) dark cloud complex at about 600 pcthat contains several bright pre-main-sequence objects (such as V1331Cyg and LkHα 321), but this paper deals in detail only with asmall region on its eastern edge, near the HAeBe star LkHα 324.That star and its distant companion LkHα 324SE lie at the apex ofa V-shaped area apparently excavated from the edge of L988, and are thebrightest members of a small cluster containing about 50Hα-emission stars. A median age of about 0.6 Myr (with largedispersion) is inferred from its color-magnitude diagram, constructedfrom VRI photometry to V=22. Keck HIRES spectra show that LkHα324SE is probably also an HAeBe. Its image is nonstellar, and within 3"to the northwest are three condensations having complex [S II] and [O I]profiles and radial velocities up to -200 km s-1. Theyprobably originate in an outflow from LkHα 324SE. A bright Ap starwith strong Si II lines is embedded in the heavy obscuration 8' to thewest. It illuminates a small reflection nebulosity, has several faintHα emitters nearby, and shares the radial velocity of L988, soclearly it was formed in that cloud. It demonstrates again that suchchemical peculiarities can be established very early in young stars ofmoderate mass.
| Spectrophotometric Studies of Galactic Nebulae - Part Twenty-Seven - MS:15 and NS:16 - High Excitation Planetary Nebulae
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