HIGH VELOCITY JETS IN WATER-FOUNTAIN PRE-PLANETARY NEBULAE

Mark Claussen, NRAO

July 30, 2003

APN III, Mt. Rainier, WA

Talk Outline

I. Water Fountain Pre-Planetary Nebulae

II. W43 A (Imai et al.)

III. IRAS 16342-3814 (Claussen et al.)

IV. More Water Fountains ?

V. Summary

July 30, 2003 APN III

Collaborators: Raghvendra Sahai and Mark Morris

High velocity H2O masers(Likkel et al. 1992)

Water fountains: sites of on-going jet formation

• V(H2O) >= 100 km/s

• Clear double peaks• Symmetric with respect to

the systemic velocity

W43A

IRAS16342-3814

IRAS19134+2131

Water fountains: sites of on-going jet formation

• Newly-formed jets or extreme super winds ?

• How old ?

• How to produce ?

• Young stellar objects ?

W43A

IRAS16342-3814

IRAS19134+2131

High velocity H2O masers (Likkel et al. 1992)

H2O maser kinematics in 2002Imai & Diamond (2003)W43 A

-500

-250

0

250

500

-1000-50005001000

Maser spot (Oct. 1994)Precessing jet model (1994.8)

Y (

AU

)

X (AU)

Maser spot (Apr. 2002)Precessing jet model (2002.3)

A consistent model at each epoch Direct estimate of the distance: ~2.6 kpc, origin location, and jet ignition time (~30 yr ago)

Period ~ 55 years Amplitude ~ 5 degrees Inclination ~ 39 degrees

The W43A jet is precessing !

IRAS 16342 –3814 Sahai et al. 1999

IRAS 16342 –3814 Sahai et al. 1999

Water Masers Mapped with the VLA --- Morris et al. 2003 -68 km/s 155 km/s

IRAS 16342-3814, VLBA February 2003

Length of this line is ~2975 mas, p.a. is 66 degrees (E of N)

2000 AU

IRAS 16342-3814, VLBA February 2003

Line drawn between strongestred and blue shifted features.

We measure theangular length ofthis line to better than one mas.

200 AU

200 AU

Red-shifted masers, VLBA February 2002

Line connectingstrongest red andblue shifted maserfeatures.

10 AU

10 AU

Blue-shifted masers, VLBA February 2002

Line connecting strongestred and blue shiftedmaser features.

IRAS16342-3814 Blue-Shifted Water Masers

February 2002March 2002April 2002May 2002

10 AU

IRAS 16342-3814 VLBA Observations

• First four epochs each separated by ~1 month in 2002

Date Separation Position Angle

03 February 2972.0 mas 66.0 deg 03 March 2973.6 66.104 April 2975.0 66.105 May 2979.6 66.1

July 30, 2003 APN III

Results of IRAS 16342-3814 VLBA Observations

• For first four epochs, separation expands at an an average rate of 287 km/s. (143 km/s in each direction if divided equally, assumes a distance of 2 kpc; Sahai et al. 1999) 3-D velocities +/- 185 km/s.

• The small scale structure is reminiscent of bow shocks seen in water maser proper motion studies of YSO’s.

• Over 3000 AU length, the masers get spread out a maximum of 150 AU, collimation of ~ 3 deg.

July 30, 2003 APN III

Results of IRAS 16342-3814 VLBA Observations

• Dynamical time scale is 150 years

• IRAS16342 jet shows no evidence of precession (curves and wiggles in the maser distribution in a single epoch) as does W43 A.

July 30, 2003 APN III

Water Fountain Pre-Planetary Nebulae

• Three examples from Likkel et al. 2 out of 3 show similar sizes and very short dynamical scales; third is presently being observed by Imai, Morris & Sahai.

• The observations of collimated jets in these transition sources suggest that PN morphology is shaped during pre-PN stage.

• Short dynamical times imply a very brief phase early on the post-AGB evolution, and so water fountain PPN are an important class of sources for understanding the onset of axisymmetry.

• Though water fountains are inherently rare, we would like to find more of them; instituted survey of candidates with the GBT. July 30, 2003 APN III

From the GBT Survey, April 2003 Claussen & Sahai 2003