Probing Jets and Disk Winds Toward Low-Mass Stars

Mark Claussen

June 10, 2003

VLBA Tenth Anniversary

Collaborators

Al Wootten, Kevin Marvel, Bruce Wilking, Ray Furuya

Crystal Brogan

Luca Moscadelli, Leonardo Testi

June 10, 2003 VLBA 10th

Schematic picture of stellar accretion (Hartmann 1998)

Launching region of wind (0.3 – 4 AU from star)

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)

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

S106 FIR Molecular Core and Water Masers (Spectrum and VLA Map)

VLBA Proper Motions of Water Masers within 25 AU of S106FIR

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

0.1 pc

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

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

Z CMa, an FU Ori Star

Water Masers in

12 AU

100 AU

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