9554(  1) - 12/06/01 12:56  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9554
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:52:02

1.Proposal Title:
Unveiling the origin of post-AGB winds through STIS data
------------------------------------------------------------------------------------
2. Proposal For  3. Cycle
AR               11
------------------------------------------------------------------------------------
4. Investigators
                                                                                     Contact?
    PI: Carmen Sanchez Contreras          Jet Propulsion Laboratory/Caltech
   CoI: Dr. Raghvendra Sahai              Jet Propulsion Laboratory/Caltech             N

------------------------------------------------------------------------------------
5. Abstract

The impact of fast, collimated jets on the spherical and slowly expanding
circumstellar envelopes of AGB stars, is believed to be responsible for the
remarkable bipolarity and high axial-velocities observed in most post-AGB objects
(protoplanetary and planetary nebulae). We have recently discovered inner, post-AGB
jets in the prototype protoplanetary nebula He 3-1475, through a preliminary
analysis of STIS long-slit spectra. The high-spatial resolution achieved by the HST
and the spectroscopic capabilities of STIS have allowed us for the first time to
study the spatio-kinematic structure of post-AGB jets in the stellar vicinity,
before they have been strongly altered by the interaction with the AGB shell. Such a
study is crucial for understanding the (unknown) mechanism that powers and collimate
the winds of post-AGB stars. We request funding to perform a comprehensive study of
the STIS spectra for the whole set of slits and gratings available for He 3-1475 and
another well studied PPN, HD 44179. A preliminary inspection of the data reveals
also in this source, a fast, bipolar outflow at ~ 40 A.U. from the star. This is the
first time that post-AGB winds are seen at such small scale. A detailed anaysis of
the STIS data is needed to tightly constraint the physical properties of the post-
AGB jets and, ultimately, to understand their origin.
------------------------------------------------------------------------------------
                                                9554(  1) - 12/06/01 12:56  - [  2]

            Summary Form for Proposal  9554

  Item                         Used in this proposal
------------------------------------------------------------------------------------------------------------------------------------
  Proposal Category            AR
------------------------------------------------------------------------------------------------------------------------------------