5857( 8) - 08/11/95 15:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5857 Version: 8 Check-in Date: ********** 1.Proposal Title: Is Mixing or Mass Loss the Cause of the Decline in ^12C/^13C in Evolved Halo Stars? ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Constantine Deliyannis Yale University CoI: Douglas Duncan University of Chicago N ------------------------------------------------------------------------------------ 6. Abstract We propose to make Boron observations which can definitively distinguish between mass loss and mixing as the cause of the low ^12C/^13C ratios seen in evolved halo stars. Rarely can a few key observations in astronomy definitively distinguish between alternate scenarios for an interesting, well defined, and instructive problem. This long-standing problem involves the low ^12C/^13C isotope ratios observed in evolved halo stars, which signal a fundamental failure of the standard stellar evolution theory. As standard models evolve off the main sequence and their convection zones deepen, CN- synthesized ^13C is dredged up, lowering slightly the ^12C/^13C ratio from ~ 90 to a final minimum of ~ 30 -- 60, in agreement with observation. However, the observed carbon isotope ratio in more evolved stars declines precipitously, contradicting the models, and reaches the CN-cycle equilibrium value of 3 -- 4. Several mechanisms have been proposed in the past to explain the low ratios. Mass loss and rotational (or other) mixing remain viable today. Lithium abundances offer some evidence in favor of mixing, but are inconclusive. Boron abundances will remain constant in the case of mass loss, decline below their maximal dilution value in the case of mixing, allowing the proposed observations to clearly discriminate between the models. This result may have important implications for cosmology as well (globular cluster ages, or big bang nucleosynthesis and dark matter). ------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 2] Observations Description ------------------------ A single GHRS observation will be made of each star (below), using the G270M grating centered at 2500 A, the wavelength of the B resonance lines. The same techniques (FP- SPLIT, the best vignetting corrections, etc.) used for achieving the highest S/N in our Cycle 0, 2, and 3 projects (section 14) will be used here. All long exposures will be broken into subexposures as is recommended. Our first target is HD 211998 (Nu Indi), in which Li dilution has progressed significantly, but B dilution should just be starting. Next, we wish to observe HD 175305 to establish empirically the maximum standard Boron dilution (see Figure 1b). Next is HD 3546, with Li detected (the ONLY such detection) about one order of magnitude below the subgiant diluted Li plateau, and with 12C/13C ratio (at ~ 8) well below that of standard models. With this star we catch the responsible mechanism in the act. Finally, we wish to observe HD 122563, in which Li is at least another factor of 3 -- 4 lower, and in which the 12C/13C ~ 4 is equal (or nearly equal) to its CN-cycle equilibrium value. We also would like to observe Groombridge 1830 (HD 103095), as described in section 10. Depletion of subgiant Boron abundances will be determined by comparing to the mean B-Fe trend defined by Duncan et al 1993, and our Cycle 3 and 4 projects (section 14). Note that in extensive Beryllium studies underway with the Keck and other telescopes, we have found that the Be- Fe trend in normal dwarfs is very tight. Since it is thought that Be and B are produced together by cosmic rays interacting with the ISM, this re-inforces the tightness of the calibrating B-Fe relation. Our previous experience has verified that S/N ~ 100 is best to derive accurate abundances from the weak B lines.We have used the absolute fluxes at 2500 A for our program stars HD 175305, 3546, 122596, and 103095 observed with IUE and reported by Cacciari et al 1985, A&AS, 61, 407, to determine directly the required exposure times. For HD 211998, which is just slightly hotter than HD 175305 (and thus has just slightly more flux at 2500 A than HD 175305), we conservatively assumed the flux from HD 175305, taking into account the difference in V magnitudes. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD175305 STAR,G V-IV RA=18H 47M 06.35S +/- 0.08", J2000 V = -182 V = 7.20 +/- 0.02 DEC=+74D 43' 31.3" +/- 0.08" B-V = 0.75 +/- 0.02 E(B-V) = 0.03 +/- 0.02 U-B = 0.14 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.0789 0.081 0.0 2 HD211998 STAR, G V-IV RA=22H 24M 37.17S +/- 0.07", J2000 V = 24 V = 5.28 +/- 0.01 DEC=-72D 15' 20.5" +/- 0.07" B-V = 0.66 +/- 0.02 E(B-V) = 0.045 +/- 0.03 U-B = -0.05 +/- 0.03 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.2901 -0.690 0.0 3 HD3546 STAR, G V-IV RA=0H 38M 33.35S +/- 0.01", J2000 V = -83 V = 4.37 +/- 0.02 DEC=+29D 18' 42.3" +/- 0.01" B-V = 0.87 +/- 0.02 E(B-V) = 0.0 +/- 0.02 U-B = 0.47 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0174 -0.254 0.0 4 HD122563 STAR, G V-IV RA=14H 02M 31.83S +/- 0.07", J2000 V = -24 V = 6.20 +/- 0.02 DEC=+9D 41' 09.6" +/- 0.07" B-V = 0.91 +/- 0.02 E(B-V) = 0.0 +/- 0.02 U-B = 0.38 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0131 -0.075 0.0 5 HD103095 STAR, G V-IV RA=11H 52M 58.77S +/- 0.01", J2000 V = -98 V = 6.45 +/- 0.02 DEC=+37D 43' 07.4" +/- 0.02" B-V = 0.75 +/- 0.02 E(B-V) = 0.0 +/- 0.01 U-B = 0.16 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.3374 -5.813 0.0 5857( 8) - 08/11/95 15:58 - [ 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 HD175305 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 5S ONBOARD ACQ FOR 11-13 SEARCH-SIZE=5 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 11 HD175305 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1414.4S SEQ 10-11 NON-INT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 12 HD175305 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 3 1305.6S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 13 HD175305 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 3 1305.6S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 5] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD211998 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 5S ONBOARD ACQ FOR 21 SEARCH-SIZE=5 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 21 HD211998 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 1 1523.2S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 6] Visit: 03 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 HD3546 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 5S ONBOARD ACQ FOR 31-32 SEARCH-SIZE=5 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 31 HD3546 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 1 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 32 HD3546 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 7] Visit: 04 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 HD122563 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 5S ONBOARD ACQ FOR 41-46 SEARCH-SIZE=5 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 41 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 1 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 42 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 43 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 44 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 45 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 46 HD122563 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 8] Visit: 05 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 HD103095 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 5S ONBOARD ACQ FOR 51-52 SEARCH-SIZE=5 Comments: STEP-SIZE=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 51 HD103095 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 1 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 52 HD103095 HRS ACCUM 2.0 G270M 2498.0 STEP-PATT=DEF, 2 1196.8S NO SPLIT FP-SPLIT=STD, COMB=FOUR, DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ 5857( 8) - 08/11/95 15:58 - [ 9] Summary Form for Proposal 5857 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=5 DOPPLER=DEF COMB=FOUR FP-SPLIT=STD STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 11-13 SEQ 10-11 NON-INT NO SPLIT ONBOARD ACQ FOR 21 ONBOARD ACQ FOR 31-32 ONBOARD ACQ FOR 41-46 ONBOARD ACQ FOR 51-52 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD175305 HD211998 HD3546 HD122563 HD103095 ------------------------------------------------------------------------------------------------------------------------------------