5876( 8) - 08/15/95 08:56 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5876 Version: 8 Check-in Date: ********** 1.Proposal Title: A GHRS Study of Circumstellar Gas Around Proto-Planetary System Candidates ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: K.-P. Cheng California State University, Fullerton CoI: Fred Bruhweiler Catholic University of America N CoI: James Neff Pennsylvania State University N ------------------------------------------------------------------------------------ 6. Abstract We propose to study the circumstellar (CS) gas around stars that are similar to Beta Pictoris, the well-known proto- planetary system candidate. This is the final stage of our multiwavelength (IR+Optical+UV) search for possible planetary systems in our sample of the 62 A stars within 25 pc. Since the evolutionary lifetimes of main- sequence A stars roughly correspond to the era of planet formation and subsequent ``heavy bombardment" in our solar system, it is likely that Beta Pic's dust+gas disk is similar to the accretion disk in the primordial solar nebula that led the formation of the Kuiper Belt. Based on our ground-based Ca II and IUE Fe II spectra of the complete volume-limited sample of A stars, we have identified at least 12 stars with possible CS gas. We plan to use the high-resolution and high-S/N capabilities of GHRS to probe the physical conditions in the CS gas. We will use atomic transitions arising from ground and low-lying metastable states to (a) verify our optical and UV CS gas detections, (b) derive accurate CS gas column densities, (c) constrain the absorbing CS gas number density and temperature, and (d) search for and characterize dynamic spectral activity similar to the mass flows seen in Beta Pic. Finally, we will combine our CS gas study with our previous IRAS CS dust survey to probe the link between stars with CS gas and those with dust disks. Our ultimate goal is to ascertain if these stars, as a group, represent some phase of planet formation. ------------------------------------------------------------------------------------ 5876( 8) - 08/15/95 08:56 - [ 2] Observations Description ------------------------ We propose to obtain high-resolution (Echelle-B) and medium- resolution (G200M) GHRS spectra of HD 217782, a possible proto-planetary system candidate we identified from our volume-limited A stars survey. All exposures will be through the LSA in the ``FP-Split" mode. We will obtain Ech-B spectra of Fe II lines centered at 2598 A (m=22) and 2607/2611 A (m=22). We will also obtain an Al III spectum centered at 1860 A with G200M. All the proposed GHRS exposure times were calculated based on our IUE data. Since accurate registration of our spectra in terms of heliocentric radial velocities is essential to the correct interpretation of mass flows, we will obtain one wavelength calibration spectrum for each grating setting. Real Time Justification ----------------------- None, all the supporting observations for this proposed project have been completed. Calibration Justification ------------------------- None Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Fred Bruhweiler*c/o the GHRS Team*Goddard Space Flight Center Ship Via: Pickup by Jenni Email: hrsfred@hrs.gsfc.nasa.gov , ------------------------------------------------------------------------------------ 5876( 8) - 08/15/95 08:56 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD217782 STAR, A0-A3 V-IV RA = 23H 02M 36.32S +/- 0.01S, J2000 V=5.09 DEC = 42D 45' 28.8" +/- 0.1" B-V=0.09 Comments: Coordinates are from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.000 0.0043 0.002 0.034 5876( 8) - 08/15/95 08:56 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD217782 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S ONBOARD ACQuisition FOR 2-5 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2 HD217782 HRS ACCUM 2.0 ECH-B 2598 FP-SPLIT=STD 1 435.2S SEQuence 2-5 NON-INTerruptible ------------------------------------------------------------------------------------------------------------------------------------ 3 WAVE HRS ACCUM SC2 ECH-B 2609 STEP-PATT=3 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 4 HD217782 HRS ACCUM 2.0 ECH-B 2609 FP- 1 435.2S SPLIT=STD,SPYBA L=NO ------------------------------------------------------------------------------------------------------------------------------------ 5 HD217782 HRS ACCUM 2.0 G200M 1860 STEP-PATT=DEF 1 598.4S ------------------------------------------------------------------------------------------------------------------------------------ 5876( 8) - 08/15/95 08:56 - [ 5] Summary Form for Proposal 5876 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN FP-SPLIT=STD STEP-PATT=3 SPYBAL=NO STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQuisition FOR 2-5 SEQuence 2-5 NON-INTerruptible ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 ECH-B G200M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD217782 WAVE ------------------------------------------------------------------------------------------------------------------------------------