6687( 6) - 03/10/96 16:15 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6687 Version: 6 Check-in Date: 10-Mar-1996 16:10:37 1.Proposal Title: How Did Stars Evolve in the Early Universe? , The Role of Metallicity ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Sara Heap Goddard Space Flight Center CoI: Dr. Allen Sweigart NASA/Goddard Space Flight Center N CoI: Dr. Alex de Koter University Space Research Assoc. N CoI: Dr. Ivan Hubeny University Space Research Assoc. N CoI: Dr. Alfred Gautschy Univ. of Basel N ------------------------------------------------------------------------------------ 6. Abstract Using GHRS spectra of post-AGB stars, we propose to test and refine a new evolutionary scheme for low- and intermediate- mass stars. This scheme takes into account the effect of metallicity on mass-loss in all evolutionary phases, including dust-enhanced mass loss on the asymptotic giant branch (Bowen 1988), pulsation- enhanced mixing and mass-loss (Gautschy 1993), and radiation-driven winds in the post-AGB phase (Heap 1986). In the transition between the AGB and CSPN phases, a star with a high metallicity (i.e. solar abundance) may be stripped of its H-rich envelope and thereby become a He-C enriched star with a Wolf-Rayet spectral type; whereas a low-Z and/or low-mass post-AGB star should pass through this stage unscathed and thus appear as a normal O or Of-type star. To test this scenario, we will determine the rate of mass-loss and iron abundance of O and WR-type post-AGB stars by comparing detailed NLTE models of the photosphere and wind to high S/N spectra obtained by GHRS. We will then construct new evolutionary tracks that take proper account of mass-loss and mixing. These results will be applied to disparate environments, such as the low-metal environment of the Magellanic Clouds and the high-metal environment of elliptical galaxies with ultraviolet excesses. ------------------------------------------------------------------------------------ 6687( 6) - 03/10/96 16:15 - [ 2] Observations Description ------------------------ Per direction from the HST TAC, only Henize 2-131 will be observed. This object is a photometric & spectroscopic variable. Ground-based spectra will be needed near the time of the GHRS observations, but they don't have to be simultaneous with the GHRS observations. I have put in a special requirement to observe in June or July 1996, which is the time I plan to get ground-based observations. Real Time Justification ----------------------- none none Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6687( 6) - 03/10/96 16:15 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PK315-13D1 STAR,PLANETARY NEBULA RA=15H 37M 11.38S +/- 0.1S,DEC=- J2000 V = 10.475 CENTRAL STAR, 71D 54' 52.5" +/- 0.3",PLATE- B-V = -0.231 ID=04C2 Comments: Position is from GSC 6687( 6) - 03/10/96 16:15 - [ 4] Visit: 01 Visit Requirements: BETWEEN 01-Jun-1996 AND 31-Jul-1996 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 PK315-13D1 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 9S ONBOARD ACQ FOR 2 EARCH-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 PK315-13D1 HRS ACQ/PEA 2.0 MIRROR-N2 1 102S ONBOARD ACQ FOR 10-60 KUP ------------------------------------------------------------------------------------------------------------------------------------ 10 PK315-13D1 HRS ACCUM 2.0 G160M 1240 1 598.4S ------------------------------------------------------------------------------------------------------------------------------------ 20 PK315-13D1 HRS ACCUM 2.0 G160M 1300 1 489.6S ------------------------------------------------------------------------------------------------------------------------------------ 30 PK315-13D1 HRS ACCUM 2.0 G160M 1350 1 489.6S ------------------------------------------------------------------------------------------------------------------------------------ 40 PK315-13D1 HRS ACCUM 2.0 G160M 1400 1 598.4S ------------------------------------------------------------------------------------------------------------------------------------ 50 PK315-13D1 HRS ACCUM 2.0 G160M 1550 1 680S ------------------------------------------------------------------------------------------------------------------------------------ 60 PK315-13D1 HRS ACCUM 2.0 G200M 1733 1 979.2S ------------------------------------------------------------------------------------------------------------------------------------ 6687( 6) - 03/10/96 16:15 - [ 5] Summary Form for Proposal 6687 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-Jun-1996 AND 31-Jul-1996 ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 10-60 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M G200M ------------------------------------------------------------------------------------------------------------------------------------ Target Names PK315-13D1 ------------------------------------------------------------------------------------------------------------------------------------