9491( 2) - 01/22/02 08:45 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9491 Version: 2 Check-in Date: 22-Jan-2002 08:44:25 1.Proposal Title: The Oxygen Abundance in the Metal-Poor Halo Star HD 140283 from UV-OH lines ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Suchitra Balachandran University of Maryland CoI: Dr. David Lambert University of Texas N CoI: Dr. Martin Asplund Uppsala University N CoI: Dr. John Carr Naval Research Lab. N ------------------------------------------------------------------------------------ 5. Abstract Oxygen is critical in numerous astrophysical contexts, including the derivation of globular cluster ages and the early history of the Galaxy's chemistry. However, its abundance, particularly in metal-poor stars, remains controversial, with optical, IR and UV abundance indicators in dwarfs and giants yielding different abundance patterns; a flat O/Fe ratio with Fe/H is suggested by OI and IR-OH lines, while a monotonically increasing O/Fe trend with decreasing Fe/H is measured from OI and UV- OH lines with a factor of 10 difference at Fe/H=-3. We propose an in-depth study of the UV- OH lines in the halo subgiant HD 140283 with R=110, 000 and S/N=200 spectra and state-of-the-art 3-D model atmospheres. Understanding UV-OH lines is particularly important because these provide the sole means of measuring the oxygen abundance in the most metal-poor stars and therefore in the early Galaxy. STIS will for the first time provide several dozen unblended UV-OH lines. Predictions about the variation of line strength with excitation potential and the asymmetries of the OH line profiles will be tested and used to refine the cool outer layers of the 3-D models where the OH lines are formed. The end result will be an accurate oxygen abundance, a thorough understanding of OH line formation, and a good characterization of the atmosphere of a metal-poor star. ------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 2] Observations Description ------------------------ As estimated with the STIS ETC and an archival IUE spectrum of HD 140283, the total integration time on the object over 25 orbits is sufficient to obtain a S/N over 200. In order to realize this practically, given the limitations of the MAMA flat field, we have decided to use the 0.2X0.06" FP-SPLIT slit set. The 25 orbits will be split into 7 visits of 3 orbits each and 1 visit of 4 orbits. The first orbit of each visit allows an integration time of about 28 minutes on the target. Each subsequent orbit allows about 48 minutes. We will rotate through the slits using a single slit in each orbit. In the final sum, the 5 slits are used for roughly the same exposure time to within 10 percent. We expect that this will allow us to reach S/N of 200 in the final spectrum. The E230H echelle will be centered at 3012 Angstrom to provide spectral coverage from 2873-3150 Angstrom at R=110, 000. We realize that there will be a small loss of wavelength coverage with the use of FP-SPLITS but this will not affect our program adversely. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD140283 STAR, G V-IV RA=15H 43M 3.76S +/- 0.00089", J2000 V = - V = 7.2+/-0.1 DEC=-10D 55' 57.9" +/- 0.00060" 171.4 E(B-V) = 0.02+/-0.02 F(3000)=32.5+/-2.5e-13 TYPE=G3IV Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE Comments: HD 140283 is a metal-poor halo subgiant. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1991.25 -0.07574 -0.302771 0.01744 9491( 2) - 01/22/02 08:45 - [ 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 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPA ------------------------------------------------------------------------------------------------------------------------------------ 3 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPA A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPB A ------------------------------------------------------------------------------------------------------------------------------------ 5 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPC A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 6 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 7 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPB ------------------------------------------------------------------------------------------------------------------------------------ 8 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPB A ------------------------------------------------------------------------------------------------------------------------------------ 9 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPC A ------------------------------------------------------------------------------------------------------------------------------------ 10 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPD A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 12 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPC ------------------------------------------------------------------------------------------------------------------------------------ 13 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPC A ------------------------------------------------------------------------------------------------------------------------------------ 14 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPD A ------------------------------------------------------------------------------------------------------------------------------------ 15 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPE A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 16 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 17 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPD ------------------------------------------------------------------------------------------------------------------------------------ 18 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPD A ------------------------------------------------------------------------------------------------------------------------------------ 19 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPE A ------------------------------------------------------------------------------------------------------------------------------------ 20 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPA A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 22 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPE ------------------------------------------------------------------------------------------------------------------------------------ 23 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPE A ------------------------------------------------------------------------------------------------------------------------------------ 24 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPA A ------------------------------------------------------------------------------------------------------------------------------------ 25 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPB A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 9] Visit: 06 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 ------------------------------------------------------------------------------------------------------------------------------------ 26 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 27 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPA ------------------------------------------------------------------------------------------------------------------------------------ 28 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPA A ------------------------------------------------------------------------------------------------------------------------------------ 29 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPB A ------------------------------------------------------------------------------------------------------------------------------------ 30 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPC A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 10] Visit: 07 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 ------------------------------------------------------------------------------------------------------------------------------------ 31 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 32 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPB ------------------------------------------------------------------------------------------------------------------------------------ 33 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPB A ------------------------------------------------------------------------------------------------------------------------------------ 34 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPD A ------------------------------------------------------------------------------------------------------------------------------------ 35 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPE A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 11] Visit: 08 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 ------------------------------------------------------------------------------------------------------------------------------------ 36 HD140283 STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 1.0 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 37 HD140283 STIS/C ACQ/PEA 0.2X0.0 G430M 4194 1 3 S CD K 6FPC ------------------------------------------------------------------------------------------------------------------------------------ 38 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 1740 S UV-MAM 6FPC A ------------------------------------------------------------------------------------------------------------------------------------ 39 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S UV-MAM 6FPD A ------------------------------------------------------------------------------------------------------------------------------------ 40 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S END ORBIT UV-MAM 6FPE A ------------------------------------------------------------------------------------------------------------------------------------ 41 HD140283 STIS/N ACCUM 0.2X0.0 E230H 3012 1 2800 S END ORBIT UV-MAM 6FPA A ------------------------------------------------------------------------------------------------------------------------------------ 9491( 2) - 01/22/02 08:45 - [ 12] Summary Form for Proposal 9491 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 0.2X0.06FPA 0.2X0.06FPB 0.2X0.06FPC 0.2X0.06FPD 0.2X0.06FPE ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430M E230H ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD140283 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4194 3012 ------------------------------------------------------------------------------------------------------------------------------------