Scientific results and prospects from the 8.2-m Subaru telescope: star forming regions

摘要

This article describe sresults of the first light observations of te Orion nebula and L1551 IRS 5 carried out with the Subaru telescope in January 1999. The new infrared images of the Orion nebula, taken udner the seeing conditions of 0".2 - 0".5, cover the area of 5'x5' centered on the Trapezium cluster, revealing details of the BN/KL region, the bright bar, and other conspicuous features as well as several new H_2 emission sources. There are more than 500 stars detected; most of them are not visible in optical images and are embedded in the molecular cloud behind the nebula. Their K'-band luminosity function confirmed the bump around 12 mag with a tail toward the fainter end of 17 mag. some of these most faint stars may be good candidates for young borown dwarfs. The J-band image of L1551 IRS 5 revealed a pair of twisted jets emanating possibly from each of the binary protostars. The two jets are spatially resolved for the first itme from the ground, with wiggly and knotty appearance similar to the R-band image taken with the Hubble Space Telescope, suggesting that the appearance is intrinsic to them and is not caused due to the spatial variation of extinction. Successive grism spectroscopy proved that the jet emission predominantly arises fro mthe (FeII) lines.