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Submillimeter Array observations of the L1157 protostellar jet

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

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Submillimeter Array observations of the L1157 protostellar jet

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  1. 5th JETSET school Submillimeter Array observations of the L1157 protostellar jet Arturo I. Gomez Centro de Radioastronomia y Astrofisica UNAM, Mexico Collaboration: Naomi Hirano & Shen-Yuan Liu Academia Sinica Institute of Astronomy and Astrophysics ASIAA, Taiwan Laurent Loinard CRyA-UNAM Mexico

  2. L1157 bipolar outflow CO(1-0) SiO (2-1) • L1157: dark cloud 440 pc distant (VLSR=+2.7 km/s); Class 0 source with 11 Lsun • Precessing bipolar outflow with a mean dynamical age of 15 000 yrs • Strongest molecular line emission from the blue-lobe in several species • Two cavities related with different ejection events (C1 older than C2) • Prototype of chemically active outflows (shock chemistry) • Chemical stratification along the lobe (Bachiller et al., 2001; Benedettini et al., 2007) C2 C1 Bachiller et al., 2001 Gueth et al., 1998

  3. SMA observations • SMA observations in the compact-north configuration • 4 pointings separated by 30” to cover the entire blue lobe • Frequency coverage 216.6 to 218.6 GHz (LSB) and 226.6 to 228.6 GHz (USB) • Spectral resolution of 406.25 kHz across 2 GHz band => 0.561 km/s • Synthesized beam ~ 3.4’’ x 2.3’’

  4. General Results • Four molecular lines detected in LSB SiO(5-4) 217.10798 GHz H2CO 3(3,0)-2(0,2) 218.22218 GHz H2CO 3(2,2)-2(2-1) 218.47561 GHz CH3OH 4(2,2)-3(1,2)E 218.44000 GHz • Molecular emission comes from S2 and S3 shocks (C2) • SiO is the strongest of the lines detected • H2CO 3(2,2)-2(2,1) and CH3OH are the weakest lines

  5. SiO (5-4) Velocity channel maps

  6. SiO (5-4) • Several clumps around S2 and S3 shocks (from -15.4 to +2.8 km/s) • 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 • SMA observations only showing the compact high-velocity emission in S2; extended low-velocity emission shown by single-dish data SMA SiO(5-4);CO(1-0) & SiO(2-1), Gueth et al., 1998

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

  8. Conclusions • Clumpy structure of SiO and H2CO, tracing the C2 cavity walls • 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 • 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

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