Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5421 Report Date: 18-Jul-95:17:21 Version: ********** Check-in Date: ********** 1.Proposal Title: ABUNDANCES OF VERY HEAVY ELEMENTS IN THE EARLY GALAXY: CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO Sub Category CHEMICAL ABUNDANCES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone John J. Cowan UNIVERSITY OF OKLAHOMA USA 405-325-3961 ------------------------------------------------------------------------------------ 7. Abstract We propose to search for spectral lines indicating the presence of the very heavy elements platinum, iridium, bismuth and osmium in the very old, metal-poor halo giant HD 122563, and to determine the relative abundances of these elements. These elements, synthesized in stellar interiors by r(apid) and s(low) neutron capture processes, have never before been detected 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 will serve to provide important constraints both on the early history and chemical evolution of the Galaxy and, indirectly, on the age of the Galaxy and the universe. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 13.40 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5421 PI: John J. Cowan Proposal Title: ABUNDANCES OF VERY HEAVY ELEMENTS IN THE EARLY GALAXY: CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ John J. Cowan UNIVERSITY OF OKLAHOMA USA Christopher Sneden UNIVERSITY OF TEXAS USA James W. Truran UNIVERSITY OF CHICAGO USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will measure the abundances of the heavy r-process elements Os,Ir, Pt and the s-process element Bi 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 A. We have chosen a very metal-poor halo giant for observations with the HST: HD 122563. This star is the brightest very metal-poor ([Fe/H] = -2.7) star in the sky, and has been analyzed repeatedly with visual wavelength spectra (see Sneden and Parthasarathy 1983, Ap. J., 257, 757). It is the halo star with the most completely determined heavy element abundance distribution. It has (roughly) a solar content relative to Fe of the lighter neutron capture element group Sr-Y-Zr, but severe-to-moderate deficiencies in the heavier Ba-...-Dy group. Additionally, the s-process elements such as Ba are much more depleted than are the r-process elements such as Eu. Finally, abundances will be derived by syntheses of the spectra obtained with the HST. The model atmospheres employed for the stars will be those adopted by Gratton and Sneden (1991a). Particular attention will be paid to the abundances of ordinary metals (e. g. Fe, Ni, Ti) determined from the new uv spectra. These abundances must agree, within observation and analysis errors, to the abundances derived from the (easily analyzed) visual wavelength spectra already on hand. Then the abundances determined from the analysis of the Pt, Ir, Os and Bi features will be compared to the abundances of the ordinary metals to ascertain the degree of enrichment of the exotic very heavy elements. We already have predicted the approximate expected strengths for the Os I, Ir I, Pt I and Bi I lines. Adopting a) model atmosphere parameters from Gilroy et al. (1988), b) recent published oscillator strengths for the lines, and c) predicted abundance ratios for these elements with respect to Ba and Eu from r-process synthesis calculations or from the solar system r-process fractions, we predict that the Pt I lines will have equivalent widths of about 20 mA, or log (W/lambda) ~ -5.2 . The Ir I, Os I and Bi I equivalent widths should be about 10 mA, or log (W/lambda) ~ -5.5 . Therefore the lines of these 4 elements should be easily seen with the high resolutions to be employed here. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We wish to use the High Resolution Spectrograph to obtain very high resolution spectra of Pt, Ir, Os and Bi. Only low excitation transitions of the neutral species of each element have detection possibilities, for the singly ionized transitions are either extremely weak or are located too far in the ultraviolet. None of the neutral species under study here have strong lines redward of 3064A and thus they are totally inaccessible from ground-based observations. We have limited our transition search to wavelengths between 2700 A and 3100 A, for our K -giant stars simply do not have enough flux in the farther UV to permit HST high resolution observations. We have chosen the following regions for our integrations: 1) 3059A (Os I), 3065A (Pt I), 3025A (Bi I); 2) 2925A (Ir I), 2930A (Pt I), 2898A (Bi I); and 3) 2998A (Pt I), 3025A (Bi I). We will use the SSA, grating 270M, and 4 substeps per diode to achieve an ultimate resolution of 50,000 while capturing about 45A of spectrum per integration. The resolution requirement is due to the crowded spectral region near 3000 A 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. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. NONE ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. NONE ------------------------------------------------------------------------------------ 8. Additional comments or special requests. NONE ------------------------------------------------------------------------------------ 9. Description of previous HST work. #3880, (Cycle 3) "CIRCUMSTELLAR AND INTERSTELLAR ABSORPTION LINES IN PLANETARY NEBULAE CENTRAL STARS", H. Dinerstein, L. Danly, S. Heap, C. Sneden. This project is unrelated to the present proposal. The data are still being gathered for this project. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). We will provide graduate students to assist in data reduction; some financial support is requested for these students. We will provide some computer services for initial data analysis. Funds are requested to purchase a small workstation to enable us to process the data at a faster rate and to do analyses not possible on the heavily subscribed department computers. We will also provide secretarial support for preparing manuscripts for publication and any graphics support required. ------------------------------------------------------------------------------------ 11. Address Information Name: JOHN J. COWAN Category: PI Institution: UNIVERSITY OF OKLAHOMA Address: DEPARTMENT OF PHYSICS AND ASTRONOMY 440 WEST BROOKS City: NORMAN State: OK Zip Code: 73019 Country: USA Telephone: 405-325-3961 Telex (or e-mail): COWAN@PHAST.NHN.UOKNOR.EDU ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5421 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD122563 A,185,140 RA = 14H 0M 4.55S +/- 0.01S, 1950 V = - 1 V = 6.20 HR5270 DEC = +09D 55' 38.80" +/- 24.7 2 B-V = +0.90 0.15" 3 U-B = +0.38 4 F-CONT(2650) = 5 E-13 5 F-CONT(3000) = 1.5 E-12 Comments: THE CONTINUUM FLUX ESTIMATE AT 2650A IS A LOWER LIMIT TO THIS STAR'S FLUX PUBLISHED BY GUSTAFSSON ET AL. (1980, A&A, 89, 255); THE FLUX AT 3000A IS AN INTERPOLATION BETWEEN THE 2650A FLUX AND THE "U" BANDPASS FLUX. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 -0.0134 +/- 0.0000 -0.0660 +/- 0.0000 0.0000 +/- 0.0000 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5421 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD122563 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S 1 1 CYCLE 4 4 ONBOARD ACQ FOR 5 2.0 Comments: STEP_TIME=0.5S; EXPECT 15000 COUNTS IN STEP-TIME TARGET IS METAL-POOR, SO UV MAGS ARE SLIGHTLY UNCERTAIN ------------------------------------------------------------------------------------------------------------------------------------ 2 HD122563 HRS ACQ/ 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25S 1 1 CYCLE 4 PEAKUP 4 ONBOARD ACQ/PEAKUP 5 FOR 3.0 Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 3 HD122563 HRS ACCUM 0.25 G270M 3060 STEP-PATT=3 8 1200S 70 1 1 CYCLE 4 FP-SPLIT=STD 2400S 4 STEP-TIME=0.2 5 COMB=FOUR Comments: TOTAL EXPOSURE=9600S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD122563 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S 1 1 CYCLE 4 4 ONBOARD ACQ FOR 5 5.0 Comments: STEP_TIME=0.5S; EXPECT 15000 COUNTS IN STEP-TIME TARGET IS METAL-POOR, SO UV MAGS ARE SLIGHTLY UNCERTAIN ------------------------------------------------------------------------------------------------------------------------------------ 5 HD122563 HRS ACQ/ 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25S 1 1 CYCLE 4 PEAKUP 4 ONBOARD ACQ/PEAKUP 5 FOR 6.0 Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 6 HD122563 HRS ACCUM 0.25 G270M 2915 STEP-PATT=3 8 1200S 70 1 1 CYCLE 4 FP-SPLIT=STD 2400S 4 STEP-TIME=0.2 5 COMB=FOUR Comments: TOTAL EXPOSURE=9600S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5421 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 HD122563 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S 1 1 CYCLE 4 4 ONBOARD ACQ FOR 5 8.0 Comments: STEP_TIME=0.5S; EXPECT 15000 COUNTS IN STEP-TIME TARGET IS METAL-POOR, SO UV MAGS ARE SLIGHTLY UNCERTAIN ------------------------------------------------------------------------------------------------------------------------------------ 8 HD122563 HRS ACQ/ 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25S 1 1 CYCLE 4 PEAKUP 4 ONBOARD ACQ/PEAKUP 5 FOR 9.0 Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 9 HD122563 HRS ACCUM 0.25 G270M 3010 STEP-PATT=3 8 1200S 70 1 1 CYCLE 4 FP-SPLIT=STD 2400S 4 STEP-TIME=0.2 5 COMB=FOUR Comments: TOTAL EXPOSURE=9600S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ 10 HD122563 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S 1 1 CYCLE 4 4 ONBOARD ACQ FOR 5 11.0 Comments: STEP_TIME=0.5S; EXPECT 15000 COUNTS IN STEP-TIME TARGET IS METAL-POOR, SO UV MAGS ARE SLIGHTLY UNCERTAIN ------------------------------------------------------------------------------------------------------------------------------------ 11 HD122563 HRS ACQ/ 0.25 MIRROR-N2 SEARCH-SIZE=5 1 25S 1 1 CYCLE 4 PEAKUP 4 ONBOARD ACQ/PEAKUP 5 FOR 12.0 Comments: STEP-TIME=1.0S ------------------------------------------------------------------------------------------------------------------------------------ 12 HD122563 HRS ACCUM 0.25 G270M 2833 STEP-PATT=3 6 1200S 60 1 1 CYCLE 4 FP-SPLIT=STD 1800S 4 STEP-TIME=0.2 5 COMB=FOUR Comments: TOTAL EXPOSURE=7200S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5421 [ 7] 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 for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 13.40 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category CHEMICAL ABUNDANCES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ONBOARD ACQ FOR 2.0 CYCLE 4; ONBOARD ACQ/PEAKUP FOR 3.0 CYCLE 4; CYCLE 4; ONBOARD ACQ FOR 5.0 CYCLE 4; ONBOARD ACQ/PEAKUP FOR 6.0 CYCLE 4; ONBOARD ACQ FOR 8.0 CYCLE 4; ONBOARD ACQ/PEAKUP FOR 9.0 CYCLE 4; ONBOARD ACQ FOR 11.0 CYCLE 4; ONBOARD ACQ/PEAKUP FOR 12.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD122563 HR5270 ------------------------------------------------------------------------------------------------------------------------------------