9886( 5) - 05/20/03 08:41 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9886 Version: 5 Check-in Date: 20-May-2003 08:39:50 1.Proposal Title: Boron in F Stars in the Hyades - Insights into the Li-Be Dip ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Ann M. Boesgaard University of Hawaii CoI: Prof. Jeremy R. King Clemson University N CoI: Prof. Constantine P. Deliyannis Indiana University System N ------------------------------------------------------------------------------------ 5. Abstract Dramatic deficiencies of Li in the mid-F stars of the Hyades were discovered by Boesgaard and Tripicco in 1986. Using ultraviolet, high-resolution spectra from the Keck 10-m telescope, Boesgaard and King have just discovered the corresponding deficiencies in Be in the same narrow temperature region in the Hyades. We propose a precision investigation into the B abundance in the Hyades F stars to ascertain if there is a B dip. Boron can only be observed with HST and we plan to use the resonance line of B I at 2497A. Each of these three light elements is destroyed inside stars, but each has a different threshold temperature: 2.5 x 10^6, 3.5 x 10^6, and 5 x 10^6 K for Li, Be, and B respectively. Consequently, these elements survive to increasingly greater depths in a star and their surface abundances act as a report on the depth and thoroughness of mixing in the star. The mixing mechanism in F stars is slow mixing, but not straight convective mixing. These observations will help determine the nature of the mixing mechanism(s), and the connection to stellar rotation. The abundance of *all three* light elements in a cluster ofknown age and metallicity provides the necessary information to discern the internal stellar processes. This mixing must be occurring in other stars of this mass range (~10-25% more massive than the sun) and can best be studied in a cluster of stars of common origin and known characteristics. The Hyades cluster at 7 x 10^8 yr is close enough to contain stars bright enough for this investigation. ------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 2] Observations Description ------------------------ In this project we wish to observe six judiciously selected F dwarfs in the Hyades to search for evidence of a B dip like the previously discovered Li dip and the newly discovered Be dip. We have chosen one star on the hot side of the dip, two in the middle of the dip, two on the cool side of the dip and one solar-type star. An important selection criterion is low v sin i ($<$20 km s$^{-1}$) in order to have sharp enough lines to derive a reliable B abundance. Previous experience has shown that a signal-to-noise ratios (S/N) of at least 50 are needed to determine accurate B abundances. For the first orbit approximately 24 minutes are taken by overhead for guide star acquisition, target acquisition, peak-up, MAMA overhead. There will be approximately 1830 seconds of exposure on the targets. For our brightest star, vb 14 on the hot side of the Li-Be dip with V = 5.71, data collected in one orbit will give S/N $\sim$100. This star has v sin i $<$ 12 km s$^{-1}$ and is the only one of the four hotter stars observed for Li that meets our low v sin i criterion. Only two stars in the center of dip region have low v sin i values. They are vB37 at 12 km s$^{-1}$ and vB13 at 18 km s$^{-1}$. These two stars are the most important stars in the program and if we devote two orbits to each of them we can achieve S/N ratios of about 100. We have selected two comparison stars at the ``Li plateau'' near T$_{\rm eff}$ of 6200 K. These stars are fainter (V = 7.1 and 7.4), but have low v sin i's of $<$12 and 9 km s$^{-1}$. Two orbits for each of these will give S/N between 55 and 65. Our solar temperature star is sharp-lined but faint so five orbits (1.4 x 10$^4$ s) are needed for S/N of 50. These stars are in an open star cluster, but none has a nearby companion to complicate the acquisition of the target. HD 26462 (= vB14 = 45 Tau = HR 1292) is the brightest star at V=5.71 and has a companion that is 4.1 mag fainter with a separation of 124.1 arcsec. The ordinary calibration procedures will be sufficient for this project. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD26462 STAR, F3-F9 RA=04H11M20.2S +/- 0.00925S, J2000 V = 36.6 V = 5.713 DEC=+05D31'22.9" +/- 0.00785" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: hot side Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.009745 0.0050 0.02589 2 HD27561 STAR, F3-F9 RA=04H21M34.73S +/- 0.00957S, J2000 V = 6.597 DEC=+14D24'35.4" +/- 0.00642" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: in Li-Be dip Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.006792 -0.01911 0.01946 3 HD26345 STAR, F3-F9 RA=04H10M42.29S +/- 0.00841S, J2000 V = 6.601 DEC=+18D25'24.0" +/- 0.00589" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: In Li-Be Dip v sin i = 18 km/s Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.007838 -0.03141 0.02322 4 HD27808 STAR, F3-F9 RA=04H24M14.5S +/- 0.01209S, J2000 V = 7.13 DEC=+21D44'10.9" +/- 0.00804" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: Li plateau Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.007375 -0.04663 0.02447 5 HD28205 STAR, G V-IV RA=04H27M35.83S +/- 0.00985S, J2000 V = 7.41 DEC=+15D35'21.3" +/- 0.0073" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: Li plateau Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.006649 -0.02516 0.02183 9886( 5) - 05/20/03 08:41 - [ 4] Visit: 01 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD26462 STIS/C ACQ F25ND3 MIRROR 1 0.1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD26462 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD26462 STIS/N ACCUM 0.2X0.0 E230M 2707 1 1804 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 5] Visit: 02 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD27561 STIS/C ACQ F25ND3 MIRROR 1 0.1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD27561 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD27561 STIS/N ACCUM 0.2X0.0 E230M 2707 1 1809 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD27561 STIS/N ACCUM 0.2X0.0 E230M 2707 1 2876 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 6] Visit: 03 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD26345 STIS/C ACQ F25ND3 MIRROR 1 0.1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD26345 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD26345 STIS/N ACCUM 0.2X0.0 E230M 2707 1 1810 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD26345 STIS/N ACCUM 0.2X0.0 E230M 2707 1 2877 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 7] Visit: 04 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD27808 STIS/C ACQ F25ND3 MIRROR 1 0.1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD27808 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD27808 STIS/N ACCUM 0.2X0.0 E230M 2707 1 1810 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD27808 STIS/N ACCUM 0.2X0.0 E230M 2707 1 2877 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 8] Visit: 05 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD28205 STIS/C ACQ F25ND3 MIRROR 1 0.1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD28205 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD28205 STIS/N ACCUM 0.2X0.0 E230M 2707 1 1810 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD28205 STIS/N ACCUM 0.2X0.0 E230M 2707 1 2877 S UV-MAM 6 A ------------------------------------------------------------------------------------------------------------------------------------ 9886( 5) - 05/20/03 08:41 - [ 9] Summary Form for Proposal 9886 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.05ND 0.2X0.06 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD26462 HD27561 HD26345 HD27808 HD28205 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2707 ------------------------------------------------------------------------------------------------------------------------------------