[DZC97] 29 , the SIMBAD biblio

The molecular cloud IC 1848A, located at the border of the extended HII region S 199, harbors the bright infrared source AFGL 4029. A young star cluster is observed in this direction. We present an optical and near infrared study of this cluster, which contains at least thirty B stars. The visual extinction affecting the stars attains 30mag, and shows large variations on very small scales. The most massive star, possibly a B1V, ionizes the ultracompact HII region G138.300+1.558. The youngest object of the cluster, AFGL 4029-IRS 1 - identical to the radio source G138.295+1.555 - is a massive pre-main-sequence object illuminating a reflection nebula. AFGL 4029-IRS 1 is luminous (∼10⁴L_☉) and highly reddened (A_V=25-30mag); displaying many of the spectral characteristics of pre-main-sequence objects (including bright and broad emission lines and the presence of FeII emission), it is very similar to the most luminous Herbig Ae/Be stars. AFGL 4029-IRS 1 shows evidence of mass ejection: it emits an ionized stellar wind with terminal velocities of about 400km/s and a mass loss rate of about 7x10^–6M_☉/yr; it is associated with a CO outflow and a high velocity optical jet; a bright unresolved H₂ clump is observed in its vicinity. The whole complex is a very efficient star forming region, as about 10% of the mass of the parental molecular cloud has been used to form B stars.