IC-1590, A YOUNG CLUSTER EMBEDDED IN THE NEBULOSITY OF NGC-281

Photoelectric and CCD photometry (tea limit of V = 17.0) is presented for 61 and 243 stars, respectively total of 279 individual stars-in an d about IC 1590, a young galactic cluster embedded in the nebulosity o f NGC 281, the H II region S184. New spectroscopic observations are al so presented for 20 stars in or near the cluster. A small amount of di fferential reddening is observed across the face of IC 1590, and is de scribed by a visual reddening relation of slope EU-B/EB-V = 0.735. Fro m near infrared photometry of bright cluster members in the I and K ba nds and a variable-extinction analysis of ZAMS members, the value of R = A(V)/EB-V, the ratio of total to selective absorption, is found to be 3.44 +/- 0.07, slightly larger than what has been found for other n earby galactic fields. Most of the cluster reddening appears to origin ate in dust clouds which are similar to 0.66 kpc and 2.0-2.2 kpc dista nt, the latter cloud lying in the immediate foreground of the cluster, which has a derived distance of 2.94 +/- 0.15 kpc (V-0-M-V = 12.34 +/ - 0.11 s.d., +/- 0.03 s.e.). IC 1590 is extremely young and has an est imated age for its 63 identified probable members of 3.5(+/- 0.2) x 10 (6) years, with very little evidence for age spread. Its well-defined sequence of 22 gravitationally-contracting stars, the choice of which is supported by star counts and reddening information, provides eviden ce for the extreme youth of the cluster's central trapezium system, HD 5005. According to the luminosity distribution of likely cluster memb ers, the initial mass function for IC 1590 has a slope of Gamma = -1.0 0 +/- 0.21, similar to what has been found for other very young cluste rs and associations. Given that the photometric study terminates at a magnitude limit marginally brighter than where embedded protostars and T Tauri variables belonging to the cluster are expected to be found, IC 1590 would make an excellent target for Hubble Space Telescope obse rvations. (C) 1997 American Astronomical Society.