5862( 0) - 07/18/95 18:21 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5862 Version: ********** Check-in Date: ********** 1.Proposal Title: Boron in very metal-poor stars: production of light elements in the early Galaxy ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Ramon J. Garcia Lopez Instituto de Astrofisica de Canarias CoI: David L. Lambert University of Texas N CoI: Bengt Edvardsson Uppsala Astronomical Observatory N CoI: Bengt Gustafsson Uppsala Astronomical Observatory N CoI: Poul Erik Nissen University of Aarhus N CoI: Dan Kiselman NORDITA N CoI: Rafael Rebolo Instituto de Astrofisica de Canarias N ------------------------------------------------------------------------------------ 6. Abstract We propose to derive the boron abundances in two very metal- deficient stars (- 2.4>=[Fe/H]>=-2.9) by observing the B I 2496.7 A line with the G270M/SSA configuration. The abundances will be computed under NLTE conditions. Both stars have also accurate determinations of lithium (including 6Li for one of them), beryllium and oxygen abundances, which will allow us to compute and interpret the abundance ratios between these elements. The available data for the star HD140283 ([Fe/H]=-2.7), for which an accurate NLTE boron abundance has been derived, seem to favour the hypothesis that boron and beryllium in Population II stars were produced by cosmic ray induced spallation reactions and not by inhomogeneous big bang nucleosynthesis. These new observations, which include what is probably the most metal-poor unevolved star known for which boron can be measured with HST, together with the results obtained for HD140283, will be the most useful diagnostic used up to now to precisely constrain the different mechanisms proposed as responsible for the light element production in the early Galaxy. ------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 2] Observations Description ------------------------ We propose to observe the B I doublet located at 2496.772 and 2497.723 A in the stars HD84937 and BD+30D3130 (with metallicities [Fe/H]=-2.4 and -2.9, respectively), using the GHRS in the low resolution G270M/SSA mode (R ~ 25000). Due to the short wavelengths of notable B lines, and the faintness of the stars, no other observing possibilities but HST are available. FP-SPLIT mode will be used in order to obtain high signal-to-noise ratios and minimise the effects of the cathode glitches and the GIMP. To obtain the highest possible resolution we shall use STEP-PATT=5. Edvardsson et al. (1994) derived the boron abundance in HD140283 (with B I 2496.772 A line equivalent width ~ 5 mA) using a high resolution spectrum with S/N~ 33. Given the expected uncertainties in the estimated abundances, the weakness of the lines, and our lower resolution it will be necessary to improve the requested S/N to a value around 100 in order to guarantee an accurate abundance determination. The B I line in BD+23D3130 is predicted have W~12 mA, and it will be blended in a G270M spectrum with a Co I line. For HD84937 we estimate W~4 for the B I line. Edvardsson et al.'s ECH-B spectrum of HD140283 gave similar equivalent widths as Duncan et al. (1992) obtained from a highest S/N G270M spectrum. Therefore, we believe the G270M spectra would provide an accurate result for the B I line in our stars. To estimate the energy flux reaching the Earth in the B I region, we took advantage of the available UV fluxes measured by IUE at Lambda 2500 A for our targets. Duncan et al. (1992) found that neither scattered light nor dark current is important for these observations. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 BD+23D3130 STAR,G V-IV,HALO, RA=17H 32M 42.05S +/- 0.01S, J2000 V=8.9 +/- 0.2 DEC=+23D 44' 13.3" +/- 0.2", TYPE=G0 PLATE-ID=02HC B-V=0.64 +/- 0.1 F-CONT(2500)=1.6 +/- 0.3 E-13 Comments: Proper motions come from the SAO Catalogue (equinox and epoch 1950). The "Epoch" quoted corresponds to the observation date for the plate used when constructing the GSC. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1982.38 -0.0245 -0.099 0.0 2 HD84937 STAR,F3-F9,HALO, RA=09H 48M 55.71S +/- 0.02S, J2000 V=-16.7 V=8.3 +/- 0.1 DEC=+13D 44' 50.8" +/- 0.3", TYPE=F5VI PLATE-ID=01X2 B-V=0.40 +/- 0.02 F-CONT(2500)=8.7 +/- 0.9 E-13 Comments: Proper motions come from the SAO Catalogue (equinox and epoch 1950). The "Epoch" quoted corresponds to the observation date for the plate used when constructing the GSC. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1985.05 0.0261 -0.788 0.025 5862( 0) - 07/18/95 18:21 - [ 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 BD+23D3130 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,L 1 1.8S ONBOARD ACQ FOR 20 OCATE=YES,SEARC H-SIZE=3 Comments: STEP-TIME=0.7S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 20 BD+23D3130 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 10S ONBOARD ACQ FOR 30-220 KUP Comments: STEP-TIME=1.0S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 30-40 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 40 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 870.4S SPLIT=TWO,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 50-60 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 60 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 70 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 70-80 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 80 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 90 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 90-100 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 100 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 110 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 110-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 120 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 130 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 130-140 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 140 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 150 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 150-160 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 160 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 170 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 170-180 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 180 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 190 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 190-200 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 200 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 210 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 210-220 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 220 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 6] Visit: 02 Visit Requirements: ON HOLD FOR 01 On Hold Comments: The star BD+23D3130 is the main target and the most interesting object in our proposal. To estimate the final S/N and exposure times we took advantage of the absolute fluxes measured at 2500 A by the IUE satellite. However, possible errors in these fluxes could produce final spectra poorer than we expect. We prefer to wait for the results from visit 01, check the spectra and S/N, and then decide between visit 02 (continue on BD+23D3130) and 03 (HD84937). 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 BD+23D3130 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,L 1 1.8S ONBOARD ACQ FOR 20 OCATE=YES,SEARC H-SIZE=3 Comments: STEP-TIME=0.7S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 20 BD+23D3130 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 10S ONBOARD ACQ FOR 30-80 KUP Comments: STEP-TIME=1.0S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 30-40 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 40 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 870.4S SPLIT=TWO,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 50-60 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 60 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 70 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 70-80 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 80 BD+23D3130 HRS ACCUM 0.25 G270M 2497 FP- 1 2344.8S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 7] Visit: 03 Visit Requirements: ON HOLD FOR 01 On Hold Comments: The star BD+23D3130 is the main target and the most interesting object in our proposal. To estimate the final S/N and exposure times we took advantage of the absolute fluxes measured at 2500 A by the IUE satellite. However, possible errors in these fluxes could produce final spectra poorer than we expect. We prefer to wait for the results from visit 01, check the spectra and S/N, and then decide between visit 02 (continue on BD+23D3130) and 03 (HD84937). 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 HD84937 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,L 1 1.8S ONBOARD ACQ FOR 20 OCATE=YES,SEARC H-SIZE=3 Comments: STEP-TIME=0.2S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 20 HD84937 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 7.5S ONBOARD ACQ FOR 30-80 KUP Comments: STEP-TIME=0.3S; expect 10000 counts in STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 30-40 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 40 HD84937 HRS ACCUM 0.25 G270M 2497 FP- 1 879.6S SPLIT=TWO,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 50-60 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 60 HD84937 HRS ACCUM 0.25 G270M 2497 FP- 1 2338.2S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 70 WAVE HRS ACCUM SC2 G270M 2497 1 DEF SEQ 70-80 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 80 HD84937 HRS ACCUM 0.25 G270M 2497 FP- 1 2338.2S SPLIT=STD,STEP- PATT=DEF,COMB=F OUR,DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5862( 0) - 07/18/95 18:21 - [ 8] Summary Form for Proposal 5862 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN LOCATE=YES SEARCH-SIZE=3 SEARCH-SIZE=5 DOPPLER=DEF COMB=FOUR STEP-PATT=DEF FP-SPLIT=STD FP-SPLIT=TWO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 30-220 SEQ 30-40 NON-INT SEQ 50-60 NON-INT SEQ 70-80 NON-INT SEQ 90-100 NON-INT SEQ 110-120 NON-INT SEQ 130-140 NON-INT SEQ 150-160 NON-INT SEQ 170-180 NON-INT SEQ 190-200 NON-INT SEQ 210-220 NON-INT ON HOLD FOR 01 ONBOARD ACQ FOR 30-80 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names BD+23D3130 WAVE HD84937 ------------------------------------------------------------------------------------------------------------------------------------