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Session 66 - Young Clusters, High-Mass YSOs and Their Environment.
Oral session, Tuesday, January 16
Salon del Rey Central, Hilton
Protostars which have yet to accrete the bulk of their initial main sequence mass from their infall envelopes, dubbed ``Class 0'' (Andre, Ward-Thompson, amp; Barsony 1993), represent the youngest (a few \times 10^4 yr) protostellar sources. The defining observational characteristics for Class 0 protostars include a high ratio of mm/submm to bolometric luminosity, the presence of molecular outflows, invisibility shortward of 10 \mum, and spectral energy distributions (SEDs) resembling modified blackbodies with T \le 30 K. Since Class 0 SEDs peak at \sim 100--200 \mum, far-infrared (FIR) data are required to produce SEDs for these sources.
The nearby Serpens star-forming cloud core is a region of great interest for Class 0 protostar searches. Millimeter continuum maps of the central 6^\prime \times 5^\prime reveal at least five cold dust continuum peaks which lack NIR counterparts (Casali, Eiroa, amp; Duncan 1993). A recent multi-transition H_2CO study of these millimeter continuum sources (FIRS1, SMM2, SMM3, SMM4, amp; S68N) confirms the presence of central heating sources and substantial masses of circumstellar gas in these objects, suggesting that they could all be Class 0 protostars (Hurt, Barsony amp; Wooten 1996).
We present new 12, 25, 60, amp; 100 \mum HIRES processed IRAS images of the Serpens cloud core at FWHM resolutions of \sim 30^\prime\prime--1^\prime. Such resolutions are necessary to help identify the individual contributions from the closely spaced sources. We use HIRES-processed point source models of the IRAS emission to determine new flux values and flux upper limits for all the protostellar candidates in the Serpens core. From the resulting SEDs we derive the dust temperature, circumstellar mass, bolometric luminosity, and evolutionary status of each protostellar candidate. Remarkably, we find all five millimeter continuum sources to share the defining characteristics of Class 0 protostars, potentially making the Serpens core the densest known collection of such objects.
