9757( 3) - 05/16/03 16:51 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9757 Version: 3 Check-in Date: 16-May-2003 16:47:51 1.Proposal Title: Abundances, Dust, and Physical Conditions in the LMC ISM ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Daniel E. Welty University of Chicago CoI: Dr. James T. Lauroesch Northwestern University N CoI: Dr. Lewis M. Hobbs University of Chicago N CoI: Dr. Donald G. York University of Chicago N CoI: Dr. J. Chris Blades Space Telescope Science Institute N ------------------------------------------------------------------------------------ 5. Abstract STIS echelle spectra of the SMC star Sk 155 have revealed patterns of gas-phase interstellar abundances (and corresponding depletions into dust) that have not been seen in the Galactic ISM. In particular, Mg and Si (generally thought to be major dust constituents) are essentially undepleted in the SMC gas --- even for components with severe depletions of Fe and Ni. We propose to obtain similar spectra of 3 LMC stars --- sampling different regions of the LMC characterized by different UV extinction curves --- first to see whether such "anomalous" abundances might also be present in the LMC (as suggested by some FUSE spectra) and then to explore the relationships between interstellar abundances, depletions, physical conditions, and dust properties in environments characterized by low metallicity and moderately strong radiation fields. These would be the first extensive UV spectra of any LMC targets at resolutions better than 6 km/s. The analysis of these spectra will have significant implications for (1) making models of interstellar dust grains (which currently rely heavily on silicates); (2) understanding the relationships between depletions, dust, and H_2 (which may be somewhat different in the Milky Way, LMC, and SMC); (3) understanding the processes affecting the ionization balance in diffuse interstellar clouds (e.g., charge exchange with large molecules, cosmic-ray ionization); (4) testing theoretical cloud models (which predict higher pressures in such environments); and (5) interpreting the gas-phase abundances observed for QSO absorption-line systems (which exhibit some similar properties). ------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 2] Observations Description ------------------------ We will observe 3 stars -- sampling different regions/environments in the LMC - - with STIS. For each star, we will obtain one E140H setting (1271) and two E230H settings (1913, 2363), with the 0.2X0.09 aperture. We will group the observations into 4 identical 5-orbit CVZ visits. Each visit will include two 85-min E140H exposures (1271), two 85-min E230H exposures (1913) and one 85-min E230H exposure (2363). The two brighter stars (Sk-67 5, Sk-69 246) will each take 1 visit; the fainter Sk-70 115 will take 2 visits. We aim to achieve S/N of about 35-40 per resolution element in the final summed spectra. The high spectral resolution is needed to determine the properties of individual components in these complex lines of sight. The UV fluxes listed for each star are from IUE low-dispersion spectra. Real Time Justification ----------------------- Observing in the CVZ cuts the orbits needed by nearly half and allows longer individual exposures on these relatively faint targets. There are 4-5 CVZ windows for each target, with total orbits ranging from 76-191. We thus request the CVZ for all three targets (all four visits). Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SK-67D5 EXT-STAR, SUPERGIANT O RA=04H50M19.0S +/- 0.3", DEC=- J2000 V = V = 11.34+/-0.02 67D39'38.1" +/- 0.3", PLATE- 314.0 TYPE=O9.7IB ID=06AF E(B-V) = 0.16+/-0.03 F(1271)=2.0+/-0.1e-12 F(1913)=1.3+/-0.1e-12 F(2363)=0.8+/-0.1e-12 Coordinate Source: GUIDE_STAR_CATALOG 2 SK-69D246 EXT-STAR, WOLF RAYET - RA=05H38M53.45S +/- 0.3", DEC=- J2000 V = 11.15+/-0.02 WN 69D02'0.8" +/- 0.3", PLATE- TYPE=WN6H ID=05ZW E(B-V) = 0.14+/-0.03 F(1271)=1.8+/-0.1e-12 F(1913)=1.2+/-0.1e-12 F(2363)=0.8+/-0.1e-12 Coordinate Source: GUIDE_STAR_CATALOG 3 SK-70D115 EXT-STAR, SUPERGIANT O RA=05H48M49.69S +/- 0.3", DEC=- J2000 V = 12.24+/-0.02 70D03'57.6" +/- 0.3", PLATE- TYPE=O6.5IAF ID=06B0 E(B-V) = 0.20+/-0.03 F(1271)=1.1+/-0.1e-12 F(1913)=0.6+/-0.1e-12 F(2363)=0.4+/-0.05e-12 Coordinate Source: GUIDE_STAR_CATALOG 9757( 3) - 05/16/03 16:51 - [ 4] Visit: 01 Visit Priority: Visit Requirements: CVZ 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 SK-67D5 STIS/C ACQ F28X50L MIRROR 1 0.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SK-67D5 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.5 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 3 SK-67D5 STIS/F ACCUM 0.2X0.0 E140H 1271 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 4 SK-67D5 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.5 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 5 SK-67D5 STIS/N ACCUM 0.2X0.0 E230H 1913 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 6 SK-67D5 STIS/N ACCUM 0.2X0.0 E230H 2363 1 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 5] Visit: 02 Visit Priority: Visit Requirements: CVZ 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 SK-69D246 STIS/C ACQ F28X50L MIRROR 1 0.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SK-69D246 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.5 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 3 SK-69D246 STIS/F ACCUM 0.2X0.0 E140H 1271 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 4 SK-69D246 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.5 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 5 SK-69D246 STIS/N ACCUM 0.2X0.0 E230H 1913 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 6 SK-69D246 STIS/N ACCUM 0.2X0.0 E230H 2363 1 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 6] Visit: 03 Visit Priority: Visit Requirements: CVZ 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 SK-70D115 STIS/C ACQ F28X50L MIRROR 1 1 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SK-70D115 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 3 SK-70D115 STIS/F ACCUM 0.2X0.0 E140H 1271 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 4 SK-70D115 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 5 SK-70D115 STIS/N ACCUM 0.2X0.0 E230H 1913 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 6 SK-70D115 STIS/N ACCUM 0.2X0.0 E230H 2363 1 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 7] Visit: 04 Visit Priority: Visit Requirements: CVZ 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 SK-70D115 STIS/C ACQ F28X50L MIRROR 1 1 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SK-70D115 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 3 SK-70D115 STIS/F ACCUM 0.2X0.0 E140H 1271 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 4 SK-70D115 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 5 SK-70D115 STIS/N ACCUM 0.2X0.0 E230H 1913 2 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 6 SK-70D115 STIS/N ACCUM 0.2X0.0 E230H 2363 1 5060 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 9757( 3) - 05/16/03 16:51 - [ 8] Summary Form for Proposal 9757 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.09 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140H E230H ------------------------------------------------------------------------------------------------------------------------------------ Target Names SK-67D5 SK-69D246 SK-70D115 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1271 1913 2363 ------------------------------------------------------------------------------------------------------------------------------------