We present deep images of dust continuum emission at 450 , 800 , and 850 \mu m of the dark cloud LDN 1689N which harbors the low-mass young stellar objects ( YSOs ) IRAS 16293 - 2422A and B ( I16293A and I16293B ) and the cold prestellar object I16293E .
Toward the positions of I16293A and E we also obtained spectra of CO-isotopomers and deep submillimeter observations of chemically related molecules with high critical densities ( HCO ^ { + } , H ^ { 13 } CO ^ { + } , DCO ^ { + } , H _ { 2 } O , HDO , H _ { 2 } D ^ { + } ) .
To I16293A we report the detection of the HDO 1 _ { 01 } – 0 _ { 00 } and H _ { 2 } O 1 _ { 10 } – 1 _ { 01 } ground-state transitions as broad self-reversed emission profiles with narrow absorption , and a tentative detection of H _ { 2 } D ^ { + } 1 _ { 10 } – 1 _ { 11 } .
To I16293E we detect weak emission of subthermally excited HDO 1 _ { 01 } – 0 _ { 00 } .
Based on this set of submillimeter continuum and line data we model the envelopes around I16293A and E. The density and velocity structure of I16293A is fit by an inside-out collapse model , yielding a sound speed of a =0.7 km s ^ { -1 } , an age of t = ( 0.6–2.5 ) \times 10 ^ { 4 } yr , and a mass of 6.1 M _ { \sun } .
The density in the envelope of I16293E is fit by a radial power law with index -1.0 \pm 0.2 , a mass of 4.4 M _ { \sun } , and a constant temperature of 16 K. These respective models are used to study the chemistry of the envelopes of these pre- and protostellar objects .

We made a large , fully sampled CO J =2–1 map of LDN 1689N which clearly shows the two outflows from I16293A and B , and the interaction of one of the flows with I16293E .
An outflow from I16293E as reported elsewhere is not confirmed .
Instead , we find that the motions around I16293E identified from small maps are part of a larger scale fossil flow from I16293B .
Modeling of the I16293A outflow shows that the broad HDO , water ground-state , and CO J =6–5 and 7–6 emission lines originate in this flow , while the HDO and H _ { 2 } O line cores originate in the envelope .
The narrow absorption feature in the ground-state water line is due to cold gas in the outer envelope .
The derived H _ { 2 } O abundance is 3 \times 10 ^ { -9 } in the cold regions of the envelope of I16293A ( T _ { kin } < 14 K ) , 2 \times 10 ^ { -7 } is warmer regions of the envelope ( > 14 K ) , and 10 ^ { -8 } in the outflow .
The HDO abundance is constant at a few \times 10 ^ { -10 } throughout the envelopes of I16293A and E. Because the derived H _ { 2 } O and HDO abundances in the two objects can be understood through shock chemistry in the outflow and ion-molecule chemistry in the envelopes , we argue that both objects are related in chemical evolution .
The [ HDO ] / [ H _ { 2 } O ] abundance ratio in the warm inner envelope of I16293A of a few times 10 ^ { -4 } is comparable to that measured in comets .
This supports the idea that the [ HDO ] / [ H _ { 2 } O ] ratio is determined in the cold prestellar core phase and conserved throughout the formation process of low-mass stars and planets .