Talk abstract
SMA Survey of Low Luminosity Young Stellar Objects in Perseus
Abstract
Very Low Luminosity Objects (VeLLOs), which have internal luminosity less than 0.1 Lsun, are considered to be either extremely young protostars (hereafter Type 1) or young brown dwarfs (Type 2) based on their low luminosity. VeLLOs can offer insights into the onset of gravitational collapse of the cores and the formation process of the substellar objects. Early studies showed a wide range of the observed VeLLO properties, perhaps due to confusion of the two types, with outflow momentum flux from $1.5\times 10^{-5}$ to $5.0\times 10^{-8}M_{\odot}$ km/s/yr and continuum flux density from 29 to 7 mJy.
In the attempt to build a systematic approach for the classification of VeLLOs, we carried out a survey toward eight low luminosity objects in Perseus with the SMA to study their compact 230 GHz continuum emission and CO (2-1) outflow activities. The continuum emission clearly divides the selected sources into two groups: strong (>30 mJy) emission in three sources resembling Type 1 and weak (< 10 mJy) emission similar to Type 2 in the other five. The three Type 1 sources are embedded in centrally concentrated SCUBA cores while two Type 2 sources appear to be at the periphery of a SCUBA core or inside a smoother core. Such a behavior indicates a close relationship between the mass assembling process with the final masses of the sources. We therefore suggest the continuum emission to be a good indicator for VeLLO type classification. On the other hand, the CO outflow momentum appears less correlated with the continuum flux and has a continuous distribution from $2.9\times 10^{-8}$ to $4.6\times 10^{-6} M_{\odot}$ km/s/yr.
In the attempt to build a systematic approach for the classification of VeLLOs, we carried out a survey toward eight low luminosity objects in Perseus with the SMA to study their compact 230 GHz continuum emission and CO (2-1) outflow activities. The continuum emission clearly divides the selected sources into two groups: strong (>30 mJy) emission in three sources resembling Type 1 and weak (< 10 mJy) emission similar to Type 2 in the other five. The three Type 1 sources are embedded in centrally concentrated SCUBA cores while two Type 2 sources appear to be at the periphery of a SCUBA core or inside a smoother core. Such a behavior indicates a close relationship between the mass assembling process with the final masses of the sources. We therefore suggest the continuum emission to be a good indicator for VeLLO type classification. On the other hand, the CO outflow momentum appears less correlated with the continuum flux and has a continuous distribution from $2.9\times 10^{-8}$ to $4.6\times 10^{-6} M_{\odot}$ km/s/yr.