Poster Presentation

Identifying Very Low-Luminosity Objects in Taurus molecule cloud

Author(s): Ren-Shiang Sung (NTHU)

Presenter: Ren-Shiang Sung (NTHU)

Very Low Luminosity Objects (VeLLOs) are the faintest protostars with intrinsic luminosity Lint < 0.1 Lsun. Their low luminosities hints that they could be either very young, very low-mass, or even very young and low-mass protostars (i.e., proto brown dwarfs). Thus, identifying VeLLOs and investigating their properties are crucial for fully understanding of the earliest stage of star formation. The goal of this paper is to uncover VeLLOs in the Taurus molecular cloud and confirm that they are true Young Stellar Objects (YSOs). We use the catalogue from Taurus Spitzer Legacy Project and apply the selection criteria developed by Dunham et al. (2008) which are based on the Spectral Energy Distributions (SEDs) of typical Class 0 and early Class I protostars. New criteria, bolometric temperature and extinction, are included to make up the lack of complete coverage of submm/mm maps in Taurus. As a result, we select 10 VeLLO candidates. In order to verify our VeLLO candidates are real YSOs, we observe 13CO (J=2-1), C18O (J=1-0), N2D+ (J=2-1), N2D+ (J=3-2), and N2H+ (J=1-0) with Arizona Radio Observatory (ARO). We detect N2H+ and N2D+ (J=2-1) in four VeLLO candidates and 13CO and C18O in all 10 VeLLO candidates (except SL05 only has 13CO). We have also SMA CO maps toward the four VeLLOs with N2H+ and N2D+ detections to investigate their outflow properties. The results tell that three of the four VeLLOs have clear large scale outflows but showing different features. In conclusion, four VeLLO candidates could be either very young, very low-mass, or even very young and low-mass protostars and the other six are more likely to be just more evolved protostars embedded in the cores.