12294( 2) - 01-Jul-2010 14:13:20 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12294 Version: 2 Check-in Time: 01-Jul-2010 14:13:20 STScI Edit Number: 0 Title Boron in F stars in the Hyades - Insights into the Li-Be Dip ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ 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 CoI: Dr. Marc H. Pinsonneault The Ohio State University Research N Foundation ------------------------------------------------------------------------------------ Abstract Dramatic deficiencies of Li in the mid-F stars of the Hyades cluster were discovered by Boesgaard and Tripicco in 1986. Using high-resolution, high signal-to-noise spectra from the Keck 10-m telescope, Boesgaard and King discovered the corresponding deficiencies in Be in the same narrow temperature region in the Hyades. We propose an investigation into the B abundance in the Hyades F stars to ascertain i f there is also a B dip. Boron can only be observed with HST; we plan to use the resonance line of B I at 2497 A. Each of these three elements is destroyed inside stars, but at different depths. The threshold temperatures are 2.5 x 10^6, 3.5 x 10^6, and 5 x 10^6 K for Li, Be, 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. Although the mixing is slow, it is 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 of known age and metallicity can provide the information needed to discern internal stellar processes. The Li and Be deficiencies occur in field and cluster stars in this mass range (1.1 - 1.25 solar masses), but the mechanisms 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. ------------------------------------------------------------------------------------ Observations Description ------------------------ In this project we plan to observe selected F dwarfs in the Hyades to search for evidence of a B dip like the previously discovered Li dip and the more recently discovered Be dip. We have observed one star on the hot side of the iL-Be dip and there is one in the HST archive on the cool side of the dip; we will now observe two stars with temperatures in the dip. We plan to do two orbits each on the two stars in the dip, vB37 and vB13, to obtain S/N of 100 for them. Our prior experience with B abundance work indicates that S/N of a minimum of 50 is desirable; we prefer to go to 100 for the all-important Li-Be dip stars to find the B abundance in them with greater 12294( 2) - 01-Jul-2010 14:13:20 - [ 2] precision, especially if B should turn out to be depleted. vB 37 = HD 27561 = HIP 20357 F5 V A(Li) = 2.29 A(Be) = 0.62 vB 13 = HD 26345 = HIP 19504 F6 V A(Li) = <1.78 A(Be) = 0.66 The light element abundances in these four stars will tell us whether there is a B dip by comparing B in stars on either side of the Li-Be dip with those in the dip. The stars outside the dip should reveal the initial B abundance in this young cluster. 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. These stars are in an open star cluster, but none has a nearby companion to complicate the acquisition of the target. The ordinary calibration procedures will be sufficient for this project. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12294( 2) - 01-Jul-2010 14:13:20 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HIP-20357 STAR, F3-F9 RA=04H21M34.7955S +/- 0.1", J2000 V = 6.578 +/- 0.0043 DEC=+14D24'35.24" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 2 HIP-19504 STAR, F3-F9 RA=04H10M42.3643S +/- 0.1", J2000 V = 6.576 +/- 0.0043 DEC=+18D25'23.71" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 12294( 2) - 01-Jul-2010 14:13:20 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HIP-20357 STIS/CCD ACQ F25ND3 MIRROR 1 0.1 S ------------------------------------------------------------------------------------------------------------------------------------ 2 HIP-20357 STIS/CCD ACQ/PEA 0.2X0.05N MIRROR 1 0.1 S K D ------------------------------------------------------------------------------------------------------------------------------------ 3 HIP-20357 STIS/NUV ACCUM 0.2X0.06 E230M 2707 1 1880.0 S -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 4 HIP-20357 STIS/NUV ACCUM 0.2X0.06 E230M 2707 1 2990.0 S -MAMA ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HIP-20357 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A HIP-20357 2 STIS/CCD ACQ/PEA 0.2X0.05 MIRROR none none none none 1 N/A K ND HIP-20357 3 STIS/NUV ACCUM 0.2X0.06 E230M 2707 none none none none 1 N/A -MAMA HIP-20357 4 STIS/NUV ACCUM 0.2X0.06 E230M 2707 none none none none 2 N/A -MAMA 12294( 2) - 01-Jul-2010 14:13:20 - [ 5] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HIP-19504 STIS/CCD ACQ F25ND3 MIRROR 1 0.1 S ------------------------------------------------------------------------------------------------------------------------------------ 2 HIP-19504 STIS/CCD ACQ/PEA 0.2X0.05N MIRROR 1 0.1 S K D ------------------------------------------------------------------------------------------------------------------------------------ 3 HIP-19504 STIS/NUV ACCUM 0.2X0.06 E230M 2707 1 1880.0 S -MAMA ------------------------------------------------------------------------------------------------------------------------------------ 4 HIP-19504 STIS/NUV ACCUM 0.2X0.06 E230M 2707 1 2996.0 S -MAMA ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HIP-19504 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A HIP-19504 2 STIS/CCD ACQ/PEA 0.2X0.05 MIRROR none none none none 1 N/A K ND HIP-19504 3 STIS/NUV ACCUM 0.2X0.06 E230M 2707 none none none none 1 N/A -MAMA HIP-19504 4 STIS/NUV ACCUM 0.2X0.06 E230M 2707 none none none none 2 N/A -MAMA 12294( 2) - 01-Jul-2010 14:13:20 - [ 6] Summary Form for Proposal 12294 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.05ND, 0.2X0.06, F25ND3 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E230M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names HIP-19504, HIP-20357 ------------------------------------------------------------------------------------------------------------------------------------