NEAR-INFRARED OBSERVATIONS OF THE Z-APPROXIMATELY-2.3 IRAS SOURCE FSC-10214+4724

Near-infrared imaging and spectroscopy of the extremely luminous IRAS source FSC 10214 + 4724 have been obtained using the Cassegrain infrared camera on the 200 inch (5.08 m) Hale Telescope. A low-resolution spectrum (lambda/d-lambda approximately 100) in the 2.0-2.4-mu-m atmospheric window shows a very strong H-alpha line at the optically determined redshift z = 2.286. The observed rest-frame equivalent width of H-alpha is 0.07 +/- 0.02-mu-m, consistent with the largest values found in quasars. The images show an unresolved source, while the near-infrared colors are somewhat redder than the mean colors of quasars observed at the same redshift. The reddening inferred is A(v) approximately 1.5 mag, with an upper limit of approximately 3.0 mag. The observations presented here cannot distinguish between starburst and quasar models for this source. Starburst models require approximately 10(12) M. of stars to have been formed over 10(7)-10(8) yr. If FSC 10214 + 4724 is a quasar, the reddening-corrected bolometric luminosity is approximately equal to the observed infrared luminosity.