Probing Jets and Disk Winds Toward Low-Mass Stars
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Transcript of Probing Jets and Disk Winds Toward Low-Mass Stars
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Probing Jets and Disk Winds Toward Low-Mass Stars
Mark Claussen
June 10, 2003
VLBA Tenth Anniversary
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Collaborators
Al Wootten, Kevin Marvel, Bruce Wilking, Ray Furuya
Crystal Brogan
Luca Moscadelli, Leonardo Testi
June 10, 2003 VLBA 10th
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Schematic picture of stellar accretion (Hartmann 1998)
Launching region of wind (0.3 – 4 AU from star)
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Proto-Stellar and Young Stellar Objects
June 10, 2003 VLBA 10th
• Low-mass protostars (~1 Msun) drive powerful outflows
• Outflows can be very large (1-5 pc)
• Outflows are collimated far from the energy source ?
• What about close in ? How are the outflows launched ?
How are they collimated or recollimated ?
• Angular resolution of the VLBA is ~1 mas at 22 GHz (0.5 AU at 500 pc)
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S106
• Bipolar HII Region
• Distance 600 pc
• Luminosity: 24 – 1000 Lsun
• Dark lane in radio and optical --- not a massive disk
• No large scale outflow known
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S106 FIR Molecular Core and Water Masers (Spectrum and VLA Map)
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VLBA Proper Motions of Water Masers within 25 AU of S106FIR
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VLBA Observations of Water Masers in S106FIR
• A newly ejected compact “microjet”
• Outflow has an age of only a few hundred years --- no large-scale molecular outflow
• Microjet is U-shaped with length of 4 AU and width of 3 AU located 25 AU from the assumed position of the star.
• Microjet is a “micro bowshock” created by the impact of the microject on the surrounding molecular gas.
• The proper motion of the water masers is about 35 km/s.
June 10, 2003 VLBA 10th
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0.1 pc
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VLBA Observations of Water Masers in HH212
• Not as clear a “microjet”, but still resembles jet structure with bow shocks.
• Jet like structure 140 AU in length, some masers located within 40 AU of the assumed position of the central source.
• The position angle of the masers agrees with H2 and SiO emission distributions
• The proper motion of the water masers is about 30 km/s.
• Residual motion flowing back along the side of the jet.
June 10, 2003 VLBA 10th
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Water Masers in Z Canis Majoris
• First detected water masers in FU Ori type object (large accretion luminosity)
• Binary system with separation 115 AU (100 mas) , p.a. 120 degrees
• Something drives 3.5 pc molecular outflow
• Submm dust disk has p.a. of 139 degrees
• Water masers found separated by 70 mas at 140 degrees p.a.
June 10, 2003 VLBA 10th
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Z CMa, an FU Ori Star
Water Masers in
12 AU
100 AU
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Some Other VLBA Observations of Water Masers in Low-Mass Stars (not comprehensive)
• IC1396 (IRAS21391+5802) --- Nimesh et al. (2000)
• NGC2071 (IRS 1 and IRS 3) --- Seth, Greenhill, Holder (2002)
• NGC1333 (SSV13, IRAS4A, 4B) --- Marvel, Wootten, et al. (2002)
• IRAS16293-2422 --- Wootten et al. (2002)
June 10, 2003 VLBA 10th
And thanks and acknowledgements to pioneering and continuing workers in this field ---
Jim Moran, Mark Reid, Luis Rodriguez, Paul Ho, Lincoln Greenhill