6748( 6) - 08/08/96 13:01 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6748 Version: 6 Check-in Date: 08-Aug-1996 12:58:30 1.Proposal Title: ABUNDANCES OF VERY HEAVY ELEMENTS IN THE EARLY GALAXY. III. ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COOL STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: JOHN COWAN UNIVERSITY OF OKLAHOMA CoI: CHRIS SNEDEN UNIVERSITY OF TEXAS N CoI: JAMES TRURAN UNIVERSITY OF CHICAGO N ------------------------------------------------------------------------------------ 6. Abstract We propose to search for spectral lines indicating the presence of the very heavy elements platinum, iridium, lead and osmium in a very old, metal-poor halo star, and to determine the relative abundances of these elements. These elements, synthesized in stellar interiors by r(apid) and s(low) neutron capture processes, had, until our very recent successful detections in Cycle 5, never before been observed in metal- poor stars because their only strong lines lie in the ultraviolet spectral region. The abundances of these r- and s- process nucleosynthesis products in halo stars, and in particular relative and absolute star-to-star comparisons, will serve to provide important constraints on models of both the early history and chemical evolution of the Galaxy and, indirectly, on the age of the Galaxy and the universe. ------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 2] Observations Description ------------------------ We will measure the abundances of the heavy r-process elements Os, Ir, Pt and the s-process element Pb in extreme Population II stars in an attempt to understand more about the early history of the Galaxy. Specifically, we will obtain spectra for all four of these elements, which have spectral lines in the ultraviolet, with wavelengths near 3000 Angstrom. We have chosen two very metal -poor halo giants for observations with the HST: HD 126238 (observed in Cycle 5) and HD 115444 (proposed here). We will use the SSA, grating 270M, and 4 substeps per diode to achieve an ultimate resolution of 50,000 while capturing about 45 Angstrom \\ of spectrum per integration. The resolution requirement is due to the crowded spectral region near 3000 Angstrom \\ in these stars, and the spectral coverage requirement, aside from increasing the number of candidate lines available per integration, will aid considerably in the setting of continua for our spectrum syntheses. The 270M grating is a better choice than ECH-B for it does not have the pronounced dropoff in throughput over short wavelength intervals that the short- order echelle grating does, and the larger spectral coverage allows at least two very heavy element transitions to be observed with each integration. For HD 115444, a comparison of its UBV colors and effective temperature with those of HD 126238 indicates that its 3000 Angstrom \\ flux is only about 25\\% that of HD 126238. To achieve a (S/N) = 50 would then require 4 hours per exposure, based upon the results of our detections in Cycle 5. We wish to observe the same three spectral regions to allow a direct comparison with our results from Cycle 5, yielding a total integration time for this new fainter star of 12 hours. Assuming three visits, adding in the target acquisition times, and overhead for each of these exposures, a sum of 18 orbits is requested for this star. Real Time Justification ----------------------- In a related effort, Sneden and Gustafsson have recently obtained optical spectra of our target star, HD 115444. One of the goals of this supporting ground-based effort is an attempt to determine the thorium abundance in this metal- poor, but heavy element rich, halo star. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD115444 STAR,GIANT O,K III-I, RA=13H 16M 42.44S +/- 0.02S, J2000 V=-27.6 V = 8.98 DEC=36D 22' 53.1" +/- 0.3", B-V = 0.78 PLATE-ID=01PR U-B = 0.18 F-CONT(2650.0)=7.0e-14 F-CONT(3000.0)=2.0e-13 Comments: Cooridinates are from GSC for 2541-528. Flux at 2650A and 3000A are lower limits to Star's Flux, from the IUE spectrum of Gustaffson et al. of the Metal-poor Giant HD 122563, adjusted for the Magnitude differences between HD 122563 And our target star HD 115444. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.133 0.012 -0.071 0.0 6748( 6) - 08/08/96 13:01 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD115444 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5 S ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD115444 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25 S ONBOARD ACQ FOR 30-40 KUP Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1280.0 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7680S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1292.8 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7757S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 5] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD115444 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5 S ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD115444 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25 S ONBOARD ACQ FOR 30-40 KUP Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1280.0 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7680S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1292.8 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7757S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 6] Visit: 03 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD115444 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5 S ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD115444 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25 S ONBOARD ACQ FOR 30-40 KUP Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1280.0 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7680S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD115444 HRS ACCUM 0.25 G270M 3060.0 COMB=FOUR,STEP-TIME=0.2, 6 1292.8 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7757S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 7] Visit: 51 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD115444 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5 S ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD115444 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25 S ONBOARD ACQ FOR 30-40 KUP Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD115444 HRS ACCUM 0.25 G270M 2915.0 COMB=FOUR,STEP-TIME=0.2, 6 1280.0 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7680S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD115444 HRS ACCUM 0.25 G270M 2915.0 COMB=FOUR,STEP-TIME=0.2, 6 1292.8 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7757S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 8] Visit: 53 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD115444 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5 S ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD115444 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25 S ONBOARD ACQ FOR 30-40 KUP Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD115444 HRS ACCUM 0.25 G270M 2833.0 COMB=FOUR,STEP-TIME=0.2, 6 1280.0 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7680S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD115444 HRS ACCUM 0.25 G270M 2833.0 COMB=FOUR,STEP-TIME=0.2, 6 1292.8 FP-SPLIT=STD,STEP-PATT=3 Comments: TOTAL EXPOSURE=7757S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 6748( 6) - 08/08/96 13:01 - [ 9] Summary Form for Proposal 6748 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=5 STEP-PATT=3 FP-SPLIT=STD STEP-TIME=0.2 COMB=FOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 30-40 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD115444 ------------------------------------------------------------------------------------------------------------------------------------