ON THE NATURE OF CLASS-I SOURCES IN RHO-OPHIUCHUS

We present nun broad-band photometry of class-I sources in rho Ophiuch us that do not show signs of outflow activity. These sources have been considered as probable protostellar candidates, since they are among the most luminous members (few tens of solar luminosities) of this sta r-forming region and are heavily embedded, as shown by their steeply i ncreasing spectra toward longer wavelengths. In comparison to some fam ous low-luminosity outflow (OF) sources, the non-outflow (NOF) sources show lower 1.3 mm fluxes, raising doubts as to their evolutionary sta ge. Our nun/submm data enabled us to derive the dust temperature and o pacity power law exponent beta. From these we derive strong constraint s on the mass surrounding these objects and conclude that NOF class-I sources in rho Ophiuchus have much less mass than OF sources with simi lar luminosities. We discuss the implications of such a finding in the evolutionary scenario of a young star.