Submillimeter Array observations of the L1157 protostellar jet Arturo I. Gomez Centro de Radioastronomia y Astrofisica UNAM, Mexico 5th JETSET school Naomi Hirano & Shen-Yuan Liu Academia Sinica Institute of Astronomy and Astrophysics ASIAA, Taiwan Laurent Loinard CRyA-UNAM Mexico Collaboration:

L1157 bipolar outflow L1157: dark cloud 440 pc distant (V LSR =+2.7 km/s); Class 0 source with 11 L sun L1157: dark cloud 440 pc distant (V LSR =+2.7 km/s); Class 0 source with 11 L sun Precessing bipolar outflow with a mean dynamical age of yrs Precessing bipolar outflow with a mean dynamical age of yrs Strongest molecular line emission from the blue-lobe in several species Strongest molecular line emission from the blue-lobe in several species Two cavities related with different ejection events (C1 older than C2) Two cavities related with different ejection events (C1 older than C2) Prototype of chemically active outflows (shock chemistry) Prototype of chemically active outflows (shock chemistry) Chemical stratification along the lobe (Bachiller et al., 2001; Benedettini et al., 2007) Chemical stratification along the lobe (Bachiller et al., 2001; Benedettini et al., 2007) Bachiller et al., 2001 CO(1-0) SiO (2-1) Gueth et al., 1998 C2 C1

SMA observations SMA observations in the compact-north configuration SMA observations in the compact-north configuration 4 pointings separated by 30” to cover the entire blue lobe 4 pointings separated by 30” to cover the entire blue lobe Frequency coverage to GHz (LSB) and to GHz (USB) Frequency coverage to GHz (LSB) and to GHz (USB) Spectral resolution of kHz across 2 GHz band => km/s Spectral resolution of kHz across 2 GHz band => km/s Synthesized beam ~ 3.4’’ x 2.3’’ Synthesized beam ~ 3.4’’ x 2.3’’

General Results Four molecular lines detected in LSB Four molecular lines detected in LSB SiO(5-4) GHz H 2 CO 3(3,0)-2(0,2) GHz H 2 CO 3(2,2)-2(2-1) GHz CH 3 OH 4(2,2)-3(1,2)E GHz Molecular emission comes from S2 and S3 shocks (C2) Molecular emission comes from S2 and S3 shocks (C2) SiO is the strongest of the lines detected SiO is the strongest of the lines detected H 2 CO 3(2,2)-2(2,1) and CH 3 OH are the weakest lines H 2 CO 3(2,2)-2(2,1) and CH 3 OH are the weakest lines

SiO (5-4) Velocity channel maps

SiO (5-4) Several clumps around S2 and S3 shocks (from to +2.8 km/s) Several clumps around S2 and S3 shocks (from to +2.8 km/s) SiO clumps located along the outer edge of the eastern wall of the cavity traced by CO emission SiO clumps located along the outer edge of the eastern wall of the cavity traced by CO emission In contrast with single-dish map, SiO(5-4) is barely seen in S1 shock In contrast with single-dish map, SiO(5-4) is barely seen in S1 shock SMA observations only showing the compact high-velocity emission in S2; extended low- velocity emission shown by single- dish data SMA observations only showing the compact high-velocity emission in S2; extended low- velocity emission shown by single- dish data SiO(5-4); CO(1-0) & SiO(2-1), Gueth et al., 1998 SMA

SiO and H 2 CO H 2 CO emission from -4 to +2 km/s along C2 H 2 CO emission from -4 to +2 km/s along C2 SiO peaks close to the apex of the bow-shock; H 2 CO peaks along the eastern cavity wall SiO peaks close to the apex of the bow-shock; H 2 CO peaks along the eastern cavity wall SiO along the outer edge of the eastern wall of the CO cavity; H 2 CO presents a cluster of clumps along the inner edge of the same part of the cavity SiO along the outer edge of the eastern wall of the CO cavity; H 2 CO presents a cluster of clumps along the inner edge of the same part of the cavity They are likely tracing different physical conditions They are likely tracing different physical conditions DEC (J2000) RA (J2000) SiO (5-4) H 2 CO* * H2CO 3(3,0)-2(0,2)

Conclusions Clumpy structure of SiO and H 2 CO, tracing the C2 cavity walls Clumpy structure of SiO and H 2 CO, tracing the C2 cavity walls SMA observations show the SiO emission tracing a compact high-velocity structure in S2 shock SMA observations show the SiO emission tracing a compact high-velocity structure in S2 shock Emission barely seen along S1 shock, likely due to the lack of short-spacing information or sensitivity, but could be an indication of the older ejection event Emission barely seen along S1 shock, likely due to the lack of short-spacing information or sensitivity, but could be an indication of the older ejection event Chemical stratification of the molecular lines, likely indicating different physical conditions through the cavity walls Chemical stratification of the molecular lines, likely indicating different physical conditions through the cavity walls Still working on the determination of physical condition through multi-line analysis of the SiO emission Still working on the determination of physical condition through multi-line analysis of the SiO emission