! File: 2474C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:06:59:34 coverpage: title_1: ABUNDANCES OF VERY HEAVY ELEMENTS IN THE EARLY GALAXY sci_cat: STELLAR ASTROPHYSICS sci_subcat: STELLAR ATMOSPHERES proposal_for: GO pi_title: DR. pi_fname: JOHN pi_mi: J. pi_lname: COWAN pi_inst: OKLAHOMA, UNIVERSITY OF pi_country: USA pi_phone: 405-325-3961 keywords_1: CHEMICALLY PECULIAR STAR, NUCLEOSYNTHESIS, ABUNDANCE hours_pri: 27.00 num_pri: 2 hrs: X funds_amount: 63062 funds_length: 12 funds_date: AUG-90 pi_position: ASSOC. PROFESSOR off_fname: WILLIAM off_mi: L. off_lname: VARLEY off_title: DIRECTOR off_inst: UNIVERSITY OF OKLAHOMA off_addr_1: 1000 ASP AVENUE off_addr_2: ROOM 314 off_city: NORMAN off_state: OK off_zip: 73019 off_country: CLEVELAND off_phone: 405-325-4757 ! end of coverpage abstract: line_1: We propose to search for spectral lines indicating the presence of line_2: the very heavy elements platinum, iridium and osmium in two very line_3: old, metal-poor halo stars, and to determine the elemental line_4: abundances. These lines, being weak and in the ultraviolet, have line_5: never before been detected in metal-poor stars. The abundances line_6: of these r-process nucleosynthesis products in halo stars will line_7: serve to provide important constraints both on the early history line_8: and chemical evolution of the Galaxy and, indirectly, on the age of line_9: the Galaxy and the universe. ! ! end of abstract general_form_proposers: lname: SNEDEN fname: CHRISTOPHER title: DR. inst: TEXAS, UNIVERSITY OF country: USA ! lname: TRURAN fname: JAMES title: DR. mi: W. inst: ILLINOIS, UNIVERSITY OF country: USA ! lname: COWAN fname: JOHN title: P.I. mi: J. inst: OKLAHOMA, UNIVERSITY OF country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We will measure the abundances of the heavy r-process elements line_2: Os-Ir-Pt in extreme Population II stars in an attempt to understand line_3: more about the early history of the Galaxy. Specifically, we will line_4: obtain spectra for all three of these elements, which have spectral line_5: lines in the ultraviolet, with wavelengths near 3000 A. We have line_6: chosen two very metal-poor halo giants for observations with the line_7: HST:HD 122563 and HD 108317.The star HD 122563 is the brightest line_8: very metal-poor ([Fe/H] = -2.6) star in the sky, and has been line_9: analyzed repeatedly with visual wavelength spectra (see Sneden and line_10: Parthasarathy 1983, (Ap. J., 257, 757).It is the halo line_11: star with the most completely determined heavy element abundance line_12: distribution.The star HD 108317 is slightly more metal-rich line_13: ([Fe/H] = -2.3), but more importantly this star is much more line_14: enriched in the neutron-capture very heavy elements than HD122563. line_15: A comparison of the abundance results of Gilroy et al.(1988) line_16: shows that the abundances for elements heavier than Zr are about 1 line_17: dex higher in HD 108317 than in HD 122563. ! question: 4 section: 1 line_1: We wish to use the High Resolution Spectrograph to obtain very high line_2: resolution spectra of Pt I lines at 2998 and 3064 A, the Ir I line line_3: at 2924 A and the Os I line at 3058 A. Our study of the relevant line_4: solar atlases and of the solar abundance studies of these elements line_5: (e. g. for Pt, see Gough, Hannaford, and Lowe 1982, J. Phys. B. 15, line_6: L431) suggests that these lines combine the best of the usual line_7: virtues of line strength and line cleanness. All other transitions line_8: of these elements are suspect on one or both of these counts, or line_9: occur at such short wavelengths that the fluxes from these cool line_10: stars are prohibitively low. Clearly the Hubble Space Telescope is line_11: necessary for our observations; the longest wavelength to be line_12: observed is 3064 A, essentially totally inaccessible from line_13: ground-based observatories. Also, we must employ one of the very line_14: high resolution echelle gratings for these observations, because line_15: a) the line crowding will be severe even in the metal-poor stars line_16: to be observed here, and b) the predicted line strengths of the line_17: Os, Ir, and Pt lines are not extremely large (see below). ! question: 5 section: 1 line_1: From the figures and formulae of section 4.1.2 (HRS Instrument line_2: Handbook), and the published stellar photometry and the assumption line_3: of E(B-V)=0,the acquisition count rates should be 5E4 using mirror line_4: N2 for HD 122563. This estimate may be a bit low because this line_5: metal-poor star is likely to be anomalously bright in the uv for line_6: its B-V colors, and so a series of 200 ms exposures should produce line_7: ideal count rates for acquisition of the object. The spectrum line_8: integration times were then estimated to produce a (S/N) of about line_9: 75 in the stellar continua with a spectral resolution of 100,000 line_10: for each observation. We must use the echelle ECH-B grating for line_11: these observations to resolve our spectral features from blending line_12: transitions of other species. Therefore we used equation 4-10 to line_13: predict exposure times, taking f=0.89 for substep pattern 6 of line_14: Table 4-15, b=0.02 from the scattered light estimates of Table 4-7 line_15: and n=1 for no spectrum binning. Then to estimate s, the signal line_16: strength, we took the sensitivity estimates of the system with the line_17: ECH-B grating (4E11 to 1E12 [counts/diode/s] per [erg/cm2/s/A]) line_18: from StScI Newsletter July 1988, and multiplied by the estimated line_19: flux for the star. For HD 122563, the flux near 3000 A was line_20: determined using the broadband UBV colors and the IUE uv spectrum. line_21: Putting all these factors together, we estimate each exposure to line_22: take about 3 hours; the increased system sensitivity at the line_23: shortest wavelengths compensates for the decreased stellar fluxes. ! question: 7 section: 1 line_1: The abundances will be derived by syntheses of the spectra line_2: obtained with the HST. The model atmospheres employed for the star line_3: will be those adopted by Gilroy et al. (1988).Particular attention line_4: will be paid to the abundances of ordinary metals (e. g. Fe, Ni, line_5: Ti) determined from the new uv spectra. These abundances must line_6: agree, within observation and analysis errors, to the abundances line_7: derived from the (easily analyzed) visual wavelength spectra line_8: already on hand. Then the abundances determined from the analysis line_9: of the Pt, Ir, and Os features will be compared to the abundances line_10: of the ordinary metals to ascertain the degree of enrichment of line_11: the exotic very heavy elements. We already have predicted the line_12: approximate expected strengths for the Os I, Ir I, and Pt I lines. line_13: Adopting a) model atmsophere parameters from Gilroy et al. (1988), line_14: b) recent published oscillator strengths for the lines, and c) line_15: predicted abundance ratios for these elements with respect to Ba line_16: and Eu from r-process synthesis calculations or from the solar line_17: system r-process fractions, we predict that the Pt I lines will line_18: have equivalent widths of about 20 mA, or log (W/lambda) ~ -5.2 . line_19: The Ir I and Os I equivalent widths should be about 10 mA, or log line_20: (W/lambda) ~ -5.5 . Therefore the lines of these 3 elements should line_21: be easily seen with the very high echelle resolutions to be line_22: employed here. ! !end of general form text general_form_address: lname: COWAN fname: JOHN mi: J. title: DR. category: PI inst: UNIVERSITY OF OKLAHOMA addr_1: DEPT. OF PHYSICS & ASTRONOMY addr_2: 440 W. BROOKS, RM. 131 city: NORMAN state: OK zip: 73019 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: HD122563 name_2: BD+10D2617 name_3: SAO120251 descr_1: STAR;GIANT;CHEMICALLY PECULIAR; descr_2: NUCLEOSYNTHESIS:ABUNDANCE;POPULATION II pos_1: RA = 14H 0M 4.55S +/- 0.01S, pos_2: DEC = +9D 55' 38.8" +/- 0.15" equinox: 1950 pm_or_par: Y pos_epoch_bj: B pos_epoch_yr: 1964.27 ra_pm_val: -0.012667 ra_pm_unct: 0.000667 dec_pm_val: -0.0710 dec_pm_unct: 0.0100 rv_or_z: V = -26.0 comment_1: UV FLUXES FROM GUSTAFSSON ET AL. comment_2: 1980 A AND A, 89, 255. fluxnum_1: 1 fluxval_1: V = 6.18 +/- 0.02, B-V = +0.91 +/- 0.02 fluxnum_2: 2 fluxval_2: TYPE = K III, E(B-V) = 0.0 fluxnum_3: 3 fluxval_3: F(2800) = 5 +/- 0.5 E-13 fluxnum_4: 4 fluxval_4: F(4400) = 1 +/- 0.1 E-11 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: HD122563 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 1.8S s_to_n: 100 fluxnum_1: 1 fluxnum_2: 2 fluxnum_3: 3 fluxnum_4: 4 priority: 1 param_1: FAINT=200.0, param_2: SEARCH-SIZE=3 req_1: ONBOARD ACQ FOR 2-4; ! linenum: 2.000 targname: HD122563 config: HRS opmode: ACCUM aperture: 0.25 sp_element: ECH-B19 wavelength: 2997.74 num_exp: 3 time_per_exp: 59.46M s_to_n: 60 fluxnum_1: 1 fluxnum_2: 2 fluxnum_3: 3 fluxnum_4: 4 priority: 1 param_1: FP-SPLIT=STD ! linenum: 3.000 targname: HD122563 config: HRS opmode: ACCUM aperture: 0.25 sp_element: ECH-B18 wavelength: 3061.45 num_exp: 3 time_per_exp: 70M s_to_n: 60 fluxnum_1: 1 fluxnum_2: 2 fluxnum_3: 3 fluxnum_4: 4 priority: 1 param_1: FP-SPLIT=STD ! linenum: 4.000 targname: HD122563 config: HRS opmode: ACCUM aperture: 0.25 sp_element: ECH-B19 wavelength: 2927.5 num_exp: 3 time_per_exp: 59.46M s_to_n: 60 fluxnum_1: 1 fluxnum_2: 2 fluxnum_3: 3 fluxnum_4: 4 priority: 1 param_1: FP-SPLIT=STD ! ! end of exposure logsheet ! No scan data records found