GAS AND DUST CONDENSATIONS AND A PECULIAR CLASS 0 OBJECT IN THE LUPUS 3 STAR-FORMING CLOUD

摘要

The Lupus 3 molecular cloud has been surveyed for dense gas and dust cores and embedded objects in radio [H~(13)CO~+ J=1-0 line and 1.2 mm continuum] and infrared [JHK_sL'MN1 bands and H_2 v = 1-0 S(1) line] wavelengths. These observations unveil a filamentary cloud, three dense cores, an embedded millimeter-wave source (MMS), and an associated elongated objectinthe K band.The properties of the three dense cores are M = 3.5-5.6 solar mass, R = 0.04-0.06 pc, and n(H_2) = (1.0—3.9) x 10~5 cm~(-3), properties similar to those in Taurus. Two of these three objects are likely to be prestellar cores, while the other one exhibits ongoing star formation. The spectral energy distribution (SED) analysis of the MMS shows that it is a remarkably cold Class 0 object with molecular outflow detected in the CO(J = 3-2) line and peculiar near-IR detections. From the estimated low bolometric temperature (39.5 K), faint bolometric luminosity (0.16 solar luminosity), and sufficiently large envelope mass (0.52 solar mass), the MMS is expected to be in a very early phase (～ 10~4 yr) of mass accretion. The K-band elongated feature appears to be scattered light originating from the embedded central object of the MMS seen through the outflow cavity opening toward HH 78 on the near side as shown by the blueshifted CO wings. The MMS has also been detected by the Spitzer Space Telescope, and its near-IR images exhibit butterfly-shaped nebulosity emission as scattered light through the bipolar cavities in contrast to that in the K band. Together with the Spitzer and NTT JHK photometric data, the observed SED has a short-wavelength cutoff suggesting a low effective temperature ( < 1400 K) of the central object.