Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3479c Report Date: 09-May-96:18:38 Version: ********** Check-in Date: ********** 1.Proposal Title: BORON IN POPULATION II DWARFS - PRIMEVAL OR SPALLATED? ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO 3479 Sub Category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Bengt Edvardsson UPPSALA ASTRONOMICAL OBSERVA SWEDEN 46-18-512488 ------------------------------------------------------------------------------------ 7. Abstract We propose to observe the B I 2496-97A lines with the GHRS in the echelle mode (SSA) in the spectra of 2 metal-poor, unevolved stars, in which beryllium has recently been found and with a new probable identification of boron in one of them. The goal is to find out whether Be and B in Pop. II dwarfs were synthesized in the Big Bang or by cosmic ray induced spallation in the early Galaxy, and in either case significantly constrain the multitudinous possibilities currently being debated in the literature. The programme will contribute significantly to the understanding of possible inhomogeneities induced by the quark to hadron phase transition in the Early Universe and of spallation processes and cosmic ray fluxes in the early Galaxy. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 19.91 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3479c PI: Bengt Edvardsson Proposal Title: BORON IN POPULATION II DWARFS - PRIMEVAL OR SPALLATED? ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Bengt Edvardsson UPPSALA ASTRONOMICAL OBSERVATORY SWEDEN X Gerard Gilmore CAMBRIDGE, UNIVERSITY OF UNITED KING X Bengt Gustafsson UPPSALA ASTRONOMICAL OBSERVATORY SWEDEN X Sveneric Johansson LUND, UNIVERSITY OF SWEDEN X David L Lambert TEXAS, UNIVERSITY OF USA Poul Erik Nissen AARHUS, UNIVERSITY OF DENMARK X ------------------------------------------------------------------------------------ 2. Scientific Justification. Page 3 ------------------------------------------------------------------------------------ 3. Description of proposed observations. 2 Extreme Population II dwarfs will be observed using the HST GHRS in the high resolution mode (with R nominally being 100,000) and with the Small Science Aperture in the wavelength region 2490-2502 A, in order to explore and measure the B I lines at 2496.779 and 2497.725 A. Observations will be performed with central wavelength=2496 A, in FP-SPLIT mode with sub-exposures in different carrousel positions, in order to ascertain high S/N and minimize effects of glitches - note that vital results will be dependent on only two weak and blended spectral lines. To obtain S/N of about 50 at the full resolution of 100,000 we shall use STEP-PATT=7. Exact centering in the SSA is probably important for the highest possible S/N. We are of course interested in getting as small as possible overhead time and the longest possible spectrum exposure times. TARGET PRIORITIES: The priorities are 1) HD140281, 2) HD84937. If a continuum S/N of less than 40 is for some reason achieved for the first ACCUM spectrum (HD140283), then the time for HD84937 should instead be used for another spectrum of HD140283. In case this will cause the observation of HD84937 to be scheduled 3 months later than those of HD140283 we will accept that penalty. POSITIONS: The positions and proper motions are from the Carlsberg Automatic Meridian Circle Catalogues No 4 and 5, and agrees very well with PPM positions. Since the right ascension of HD140283 differs by 3.0 arc-seconds from the SAO catalogue value (when both are precessed to the Equinox J2000 and Epoch 1992.5) we have decided to use a search size of 5. CENTRAL WAVELENGTHS: The best BI line has a lab. wavelength of 2496.779 A. From Fig 4.16 in the GHRS instrument handbook the least granulated part of the diode array is at diode positions 265 to 290, so that line should land near diode 277. Assuming that a higher diode position value corresponds to a longer wavelength and that the central wavelength falls at diode position 250 the central wavelength should be about 27 diodes times 0.023 A = 0.62 A bluewards of the actual line wavelength, that is at 2496.15 A. (We assume order No m=23, and mlambda about 57500) The radial velocity of HD140283 is -171 km/s corresponding to a blueshift of 1.425 A: the central wavelength should thus be 2494.7 A. The radial velocity of HD84937 is -19 km/s corresponding to a blueshift of 0.16 A: the central wavelength should thus be 2496.0 A. Since BRIGHT=RETURN is not yet available for SSA ACQ/Peakup, BRIGHT and FAINT limits have been added for those. For HD140283 the count rates from Duncan et al GO observations at this wavelength may be used to check. HD84937 is very likely to be 70 percent as bright as HD140283 at 2500 A. EXPOSURE TIMES: Since exposure times between 5 and 10 minutes are recommended to avoid GIMP we have selected an exposure time of 336 seconds. This is an even multiple (60) of STEP-PATT * FP- SPLIT * STEP-TIME which is 7 * 4 * 0.2 = 5.6 seconds. The default STEP-TIME of 0.2 seconds was adopted. SPECTRUM-Y-BALANCE: In the GHRS Instrument Handbook, Sect. 3.3.2.1 The possibility of a SPECTRUM-Y-BALANCE is mentioned. Since this is not mentioned among the HRS ACCUM Instrument Parameters, we have assumed below that this is performed by default before long exposures like these. CALIBRATION SPECTRA We assume that standard calibration spectra will be useful for the spectrum reductions, if a higher quality as regards spectral resolution or S/N would be achieved with special calibration exposures we would be interested in using some spacecraft time for such. Exact ABSOLUTE wavelength calibration is not important, and not worth extra spacecraft time. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. No other possibility but vacuum-ultraviolet spectroscopy at high resolution exists for measuring Boron abundances in Pop. II dwarfs. Previous attempts with IUE prove the resolution and S/N achievable for these apparently rather faint stars to be too low. The project is founded on observations with large Earth- based telescopes (the AAT and the WHT) in the near ultraviolet spectrum of Be. Further complementary observations in the 3130 A region will be made to reduce the errors in the Be results further. Page 4 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. In order to ascertain a S/N ratio of at least 40 for our highest priority target HD140283 we request that this star is observed first (lines 1-3) and that we then get the possibility to examine the resulting S/N, before deciding whether to use the rest of our time for the second priority star HD84937 (lines 4-6) or to use it for another spectrum of HD140283 (lines 14-16). ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The spectra will be reduced using STSDAS software, with facilities at ST-ECF and at Cambridge, Uppsala and Aarhus Universities. We expect to be able to make the synthetic spectrum analysis with a pretty complete line list. The wavelength region will be scrutinized in high-resolution laboratory spectra for ascertaining identifications and estimating branching ratios and hyperfine structure at the Physics Institute of the Lund University. The analysis of the spectra will be carried out at Uppsala using Uppsala model atmospheres and detailed synthetic spectra at the highest standard possible to achieve. Effects of departures from LTE and inhomogeneities in the atmospheres will be explored. Complementary observations will be made with the Anglo-Australian Telescope and the William Herschel Telescope. 10 and 4 nights respectively, have been given to our project at these telescopes - 4 nights at the AAT have already been used, another 6 are granted in September 1991, and 4 nights at WHT in June 1992. This will guarantee that very accurate Be abundances will have been derived for our programme stars in early spring 1992, as well as for a number of other Pop. II stars. PEN has recently obtained spectra, at R~30,000 and S/N~100, at the ESO 3.6m telescope in the wavelength region 5000-6000 A for our programme stars. These will be analyzed in September this year, yielding more accurate determinations of the abundances of iron, calcium and magnesium, and hopefully safer values of the surface gravity parameters; all leading to higher accuracy in our analysis of the HST GHRS spectra. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. a. HST program numbers and titles, and specification whether they are related to this project or not: GG: K2684 participates in the Medium Deep Survey Key Project, with 200 hours of time allocated in Cycle 1, not related DLL: GTO1063, "The extended atmosphere of Betelgeuse", not related GTO1064, "Boron in Main Sequence stars", related to this project: DLL has received GTO time in cycle 0 for the study of boron in three metal poor dwarfs (HD 140283, 19445, 201891) and in three disk F dwarfs (Procyon, iota Peg, theta Uma). GTO1065, "Isotopic abundances of carbon and oxygen and fractionation in interstellar carbon monoxide", not related GTO1066, "Carbon chemistry in interstellar diffuse clouds - the C2 molecule", not related GTO1067, "Old novae and cataclysmic variables - DQ Her and G61-29", not related GTO1068, "Epsilon Aurigae - A search for the secondary", not related GTO1069, "Interstellar boron and the boron isotopic ratio", not related since it concerns boron in the Galaxy today. BG + PEN: GTO1258, "Chemical evolution and history of star formation in the LMC", not related b. Summary of main results obtained from previous related programs: Observations of two of the three stars in project GTO1064 have already been obtained, and preliminary results are at hand: For HD 140283 an upper limit (marginally a detection) of the boron abundance, log(B/H)=-12.1, is found. For HD 201891 a much larger upper limit is suggested. A paper on B in Pop. II stars is in preparation. c. No publications. Page 5 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Adequate computer resources and personnel are available at all participating institutes. STSDAS and IRAF are available at Cambridge University and will be installed at Aarhus University and at Uppsala. Programs for model atmospheres and synthetic spectrum analyses are developed and running at Uppsala. ------------------------------------------------------------------------------------ 11. Address Information Name: BENGT EDVARDSSON Category: PI Institution: UPPSALA ASTRONOMICAL OBSERVATORY Address: BOX 515 City: S-751 20 UPPSALA State: Zip Code: Country: SWEDEN Telephone: (+46) 18 51 24 88 Telex (or e-mail): 76024 UNIVUPS S ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3479c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 HD140283 BD- A,133 RA = 15H 43M 3.983S +/- J2000 V=-171 1 V = 7.23, TYPE = F3 VI 10D4149 0.02S, 2 B-V = 0.49 +/- 0.02 DEC = -10D 55' 57.13" +/- 3 U-B = 0.20 +/-0.02 0.3" 4 F(2500) = 1.1 +/- 0.3 E-12 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J 1988.38 -0.0756 +/- 0.0013 -0.3010 +/- 0.0200 0.0300 +/- 0.0200 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD84937 A,133 RA = 9H 48M 55.742S +/- J2000 V=-19 1 V = 8.33, TYPE = F0 VI GSC0834- 0.02S, 2 B-V = 0.37 +/- 0.02 00654 DEC = 13D 44' 50.03" +/- 3 U-B = -0.20 +/- 0.03 BD+14D2151 0.3" 4 F(2500) = 0.79 +/- 0.2 E-12 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J 1986.09 0.0257 +/- 0.0002 -0.7730 +/- 0.0010 0.1000 +/- 0.0500 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3479c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 HD140283 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=5 1 5S 4 1 ONBOARD ACQ FOR 2- FAINT=8000 3 BRIGHT=65535 CYCLE 2 Comments: THE STAR WAS OBSERVED IN CYCLE 1 BY D.DUNCAN AND COLLEAGUES (GTO). (GHRS, LSA, WAVEL.=2500) STEP-TIME=0.2S ASSUMED ------------------------------------------------------------------------------------------------------------------------------------ 2 HD140283 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 4 1 ONBOARD ACQ FOR 3 PEAKUP CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD140283 HRS ACCUM 0.25 ECH-B 2494.7 FP-SPLIT=STD 65 336S 50 4 1 CYCLE 2 STEP-PATT=7 21840S Comments: COMB-ADDITION=4 DEFAULT ------------------------------------------------------------------------------------------------------------------------------------ 4 HD84937 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=5 1 5S 4 2 ONBOARD ACQ FOR 5- FAINT=5600 6 BRIGHT=65535 CYCLE 2 COND IF HD140283 SNR > 40 / 4-6 SELECT 1 OF 4-6 OR Comments: STEP-TIME=0.2S ASSUMED 14-16 ------------------------------------------------------------------------------------------------------------------------------------ 5 HD84937 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 4 2 ONBOARD ACQ FOR 6 PEAKUP CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 6 HD84937 HRS ACCUM 0.25 ECH-B 2496.0 FP-SPLIT=STD 87 336S 55 4 2 CYCLE 2 STEP-PATT=7 29232S Comments: COMB-ADDITION=4 DEFAULT STEP- TIME=0.2 DEFAULT ------------------------------------------------------------------------------------------------------------------------------------ 14 HD140283 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=5 1 5S 4 2 ONBOARD ACQ FOR 15 FAINT=8000 -16 BRIGHT=65535 CYCLE 2 COND IF HD140283 SNR < 40 / 14-16 Comments: STEP-TIME=0.2S ASSUMED FAINT MAY NEED ADJUSTING ------------------------------------------------------------------------------------------------------------------------------------ 15 HD140283 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 4 2 ONBOARD ACQ FOR 16 PEAKUP CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 16 HD140283 HRS ACCUM 0.25 ECH-B 2494.7 FP-SPLIT=STD 87 336S 65 4 2 CYCLE 2 STEP-PATT=7 29232S Comments: COMB-ADDITION=4 DEFAULT ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3479c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 FAINT=8000 BRIGHT=65535 FP-SPLIT=STD STEP-PATT=7 FAINT=5600 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 19.91 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2-3; CYCLE 2 ONBOARD ACQ FOR 3; CYCLE 2; ONBOARD ACQ FOR 5-6; COND IF HD140283 SNR > 40 / 4-6; SELECT 1 OF 4-6 OR 14-16 ONBOARD ACQ FOR 6; ONBOARD ACQ FOR 15-16; COND IF HD140283 SNR < 40 / 14-16 ONBOARD ACQ FOR 16; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 ECH-B ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD140283 BD-10D4149 HD84937 GSC0834-00654 BD+14D2151 ------------------------------------------------------------------------------------------------------------------------------------