Abstract
We present near-infrared (H, K'), CO (2-1), CS (2-1), and 1.3 mm continuum data for 31 southern objects [δ(1950) ≤ 10°] known to have extremely red IRAS colors [Fν(100 μm) > Fν(60 μm) > Fν(25 μm) > 20 × Fν(12 μm)]. The data are meant to help reveal new, very young stellar objects. K'-band near-infrared counterparts to the IRAS point sources are detected in 22 of 25 good K' images. Most K' counterparts are multiples. Eighteen of 21 objects were detected in CS, implying the presence of dense gas. Completing the set of CS (2-1) spectra by including the data of Bronfman, Nyman, & Ray, we still find only three nondetections among all 31 objects; these three were also not detected in K'. Wings indicative of outflows are found in a large fraction (20/30) of CO spectra. Twenty-six of 31 observations in the millimeter continuum were detections and point to the presence of large amounts of circumstellar matter. Most of the objects have 103-105 times solar luminosity; we speculate that most contain at least one massive star capable of producing a compact/ultracompact H II region.
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