! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 5856,v 5.1 1995/06/28 19:18:32 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Karla Peterson ! Phone: 410 338-4774, E-mail: peterson@stsci.edu ! ! This partially completed template was generated from your Phase I proposal. ! Proposal_Information ! Section 4 Title: ABUNDANCES OF VERY HEAVY ELEMENTS IN THE EARLY GALAXY. II. Proposal_Category: GO Scientific_Category: Cool Stars Cycle: 5 Investigators PI_name: JOHN COWAN PI_Institution: UNIVERSITY OF OKLAHOMA CoI_Name: CHRIS SNEDEN CoI_Institution: UNIVERSITY OF TEXAS Contact: ! Y or N (designate at most one contact) CoI_Name: JAMES TRURAN CoI_Institution: UNIVERSITY OF CHICAGO Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) We propose to search for spectral lines indicating the presence of the very heavy elements platinum, iridium, bismuth 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, 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. Questions ! Free format text (please update) Observing_Description: We will measure the abundances of the heavy r-process elements Os,Ir, Pt and the s-process element Bi in the extreme Population II star HD 126238 in an attempt to understand more about the early history and age 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 Angstroms, in this very metal-poor halo giant. In these observations, we will determine the abundances of the r- and s-process elements in HD 126238, which is more metal-rich (Fe/H = -1.7; Gratton and Sneden 1991, 1994) than HD 122563, another metal-poor halo giant which we observed with HST in Cycle 4. Among the heavier neutron-capture elements, Gratton and Sneden (1994) show that the abundance pattern of the Sr-Y-Zr group is nearly identical in the two stars: Sr/Fe = +0.01, Y/Fe = -0.36, and Zr/Fe = +0.08, with uncertainties of +/- 0.10 for each of these abundance ratios. Obviously, this suggests that the lines of the Pt-Ir-Os-Bi group ought to be 10 times stronger in HD 126238 than in HD 122563. The abundances of the heavier Ba-...-Dy group in HD 126238 are in their solar mix with respect to Fe, strikingly different than in HD 122563. 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 126238, a comparison of its UBV colors and effective temperature with those of HD 122563 (for example, although its V magnitude is 1.5 greater than that of HD 122563, it is 400K warmer so that its U is only 1.2 greater) indicates that its 3000 Angstrom \ flux is about .40 that of HD 122563. The total observing time of 13 orbits will allow us to achieve the necessary S/N ratio (= 50), and thus to determine the abundances the very heavy elements in HD 126238. Comparisons of the abundances in this very old star with the earlier stellar abundance determinations from Cycle 4 will provide a measure of the chemical evolution of the Galaxy. Real_Time_Justification: Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: HD126238 Alternate_Names: GSC7817-00861,CD-43D9039,CPD-43D6541,SAO224910 Description: STAR,GIANT O,K III-I, Position: RA = 14H 25M 30.03S +/- 0.05S, DEC = -43D 38' 35.7" +/- 0.5", PLATE-ID = 011M Equinox: J2000 Epoch: 1976.412 Rv_or_z: V = +252.2 RA_PM: 0.0024 Dec_PM: -0.118 Annual_Parallax: 0.0 Flux: V = 7.70, B-V = 8.5 E-1, U-B = 1.9 E-1, F-CONT(2650.0) = 2.0 E-13, F-CONT(3000.0) = 6.0 E-13 Comments: Coords are from GSC. FLUX AT 2650A IS A LOWER LIMIT TO STAR'S FLUX, FROM THE IUE SPECTRUM OF GUSTAFSSON ET AL (1980,A&A) OF THE METAL-POOR GIANT HD122563, ADJUSTED FOR THE MAGNITUDE DIFFERENCES BETWEEN HD122563 AND OUR TARGET HD126238. THE FLUX AT 3000A IS INTERPOLATED BETWEEN THE 2650A FLUX AND THE "U" BANDPASS FLUX. Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Exposure_number: 10 Target_Name: HD126238 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N2 Wavelength: Optional_Parameters: BRIGHT=RETURN Number_of_iterations:1 Time_Per_Exposure: 1.8S Special_Requirements:ONBOARD ACQ FOR 20 Comments: STEP_TIME=0.2S; EXPECT 7500 COUNTS IN STEP-TIME TARGET IS METAL-POOR, SO UV MAGS ARE SLIGHTLY UNCERTAIN Exposure_number: 20 Target_Name: HD126238 Config: HRS Opmode: ACQ/PEAKUP Aperture: 0.25 Sp_Element: MIRROR-N2 Wavelength: Optional_Parameters: SEARCH-SIZE=5 Number_of_iterations:1 Time_Per_Exposure: 10S Special_Requirements:ONBOARD ACQ FOR 30-60 Comments: STEP-TIME=0.4S Exposure_number: 30 Target_Name: HD126238 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: G270M Wavelength: 3060.0 Optional_Parameters: COMB=FOUR, FP-SPLIT=STD, STEP-PATT=3 Number_of_iterations:6 Time_Per_Exposure: 1817.6s Special_Requirements: Comments: TOTAL EXPOSURE=10905.6S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. Exposure_number: 60 Target_Name: HD126238 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: G270M Wavelength: 2915.0 Optional_Parameters: COMB=FOUR, FP-SPLIT=STD, STEP-PATT=3 Number_of_iterations:6 Time_Per_Exposure: 1817.6s Special_Requirements: Comments: TOTAL EXPOSURE=10905.6S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. Exposure_number: 70 Target_Name: HD126238 Config: HRS Opmode: ACQ/PEAKUP Aperture: 0.25 Sp_Element: MIRROR-N2 Wavelength: Optional_Parameters: SEARCH-SIZE=3 Number_of_iterations:1 Time_Per_Exposure: 3.6s Special_Requirements:ONBOARD ACQ FOR 90 Comments: STEP-TIME=0.4S Exposure_number: 90 Target_Name: HD126238 Config: HRS Opmode: ACCUM Aperture: 0.25 Sp_Element: G270M Wavelength: 2833.0 Optional_Parameters: COMB=FOUR, FP-SPLIT=STD, STEP-PATT=3 Number_of_iterations:5 Time_Per_Exposure: 2560s Special_Requirements: Comments: TOTAL EXPOSURE=12800S--BREAK UP TO AVOID DRIFT DUE TO GIMP; S/N IS PER SUBSTEP; WANT HIGH S/N IN EACH SUBSTEP FOR DECONVOLUTION. Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! DEPARTMENT OF PHYSICS AND ASTRONOMY ! 440 W. BROOKS, ! UNIVERSITY OF OKLAHOMA,NORMAN, ! OK 73019 ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address ! ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator