We present new infrared , submillimeter , and millimeter observations of the dense core L673-7 and report the discovery of a low-luminosity , embedded Class 0 protostar driving a molecular outflow .
L673-7 is seen in absorption against the mid-infrared background in 5.8 , 8 , and 24 \mu m Spitzer images , allowing for a derivation of the column density profile and total enclosed mass of L673-7 , independent of dust temperature assumptions .
Estimates of the core mass from these absorption profiles range from 0.2 - 4.5 M _ { \odot } .
Millimeter continuum emission indicates a mass of \sim 2 M _ { \odot } , both from a direct calculation assuming isothermal dust and from dust radiative transfer models constrained by the millimeter observations .
We use dust radiative transfer models to constrain the internal luminosity of L673-7 , defined to be the luminosity of the central source and excluding the luminosity from external heating , to be L _ { int } = 0.01 - 0.045 L _ { \odot } , with L _ { int } \sim 0.04 L _ { \odot } the most likely value .
L673-7 is thus classified as a very low luminosity object ( VeLLO ) , and is among the lowest luminosity VeLLOs yet studied .
We calculate the kinematic and dynamic properties of the molecular outflow in the standard manner .
From the outflow properties and standard assumptions regarding the driving of outflows , we calculate the time-averaged protostellar mass accretion rate , total protostellar mass accreted , and expected accretion luminosity to be \langle \dot { M } _ { acc } \rangle \geq 1.2 \times 10 ^ { -6 } \frac { \mathrm { sin } i } { % \mathrm { cos } ^ { 2 } i } M _ { \odot } yr ^ { -1 } , M _ { acc } \geq 0.07 \frac { 1 } { \mathrm { cos } i } M _ { \odot } and \mbox { $L _ { acc } $ } \geq 0.36 L _ { \odot } , respectively .
The discrepancy between this calculated L _ { acc } and the L _ { int } derived from dust radiative transfer models indicates that the current accretion rate is much lower than the average rate over the lifetime of the outflow .
Although the protostar embedded within L673-7 is consistent with currently being substellar , it is unlikely to remain as such given the substantial mass reservoir remaining in the core .