8273( 4) - 09/22/99 13:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8273 Version: 4 Check-in Date: 10-Mar-1999 11:08:03 1.Proposal Title: The Oxygen Abundance in Translucent Interstellar Clouds ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: David Meyer Northwestern University CoI: Dr. James T. Lauroesch Northwestern University N CoI: Prof. Ulysses J. Sofia Whitman College N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain high-resolution STIS echelle observations of the interstellar O I Lambda1356 absorption toward a sample of stars behind six translucent clouds characterized by large H I column densities and high extinctions (1.10 <=sssim A_V <=sssim 2.82). Previous GHRS measurements of this weak feature in diffuse clouds (A_V <=sssim 1) have shown no evidence of density-dependent O depletion from the gas phase and indicate a total (gas + dust) interstellar O abundance that is about 2/3 of the solar value. Models of translucent clouds predict enhanced depletions of gaseous O into molecules and dust by a factor of 2 or so over those of diffuse sightlines depending on the cloud homogeneity, grain characteristics, and other factors. The primary goals of our proposed investigation are to: (1) accurately determine if the O depletion is enhanced in translucent clouds, and (2) assess the gaseous O abundance spread in terms of extinction variations. With regard to the latter objective, our targeted sightlines sample a wide variety of UV extinction properties and values for the ratio of total-to-selective extinction (3 > R > 5). The lack of any enhanced O depletion among these translucent clouds, especially if the abundance spread is narrow, would signify that the grain characteristics are irrelevant to this issue for extinctions of A_V <=sssim 3. ------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 2] Observations Description ------------------------ begintabularccccccccc Star & Spectral & V & E(B--V) & R & log N(H I) & log n(H I) & Exposure & Orbits , & Type & & & & (cm^-2) & (cm^-3) & Time (s) & , HD27778 & B3 V & 6.36 & 0.38 & 2.9 & 21.30 & 0.48 & 4200 & 2 , HD37021 & B0 V & 7.96 & 0.54 & 5.2 & 21.48 & 0.30 & 1200 & 1, HD37061 & B0.5 V & 6.83 & 0.47 & 5.1 & 21.78 & 0.50 & 1300 & 1 , HD37903 & B1.5 V & 7.81 & 0.35 & 4.1 & 21.18 & -0.19 & 1700 & 1 , HD147888 & B3 V & 6.74 & 0.52 & 4.1 & 21.70 & 0.92 & 1700 & 1 , HD207198 & O9 II & 5.96 & 0.59 & 2.8 & 21.34 & - 0.06 & 4600 & 2 , endtabular vspace.2in Our goal is to obtain high-resolution STIS echelle observations of the interstellar O I Lambda1356 and Kr I Lambda1236 absorption in the translucent cloud sightlines listed above. We can observe both of these lines simultaneously toward each target with one setup of the E140H grating centered at 1271 Angstrom\ (covering 1170 to 1372 Angstrom). This setup will also cover other interstellar lines such as the Mg II Lambda1240 doublet which can serve as a saturation probe and the CO absorption bands centered near 1368, 1344, and 1322 Angstrom\ which will indicate how much O is tied up in this molecule. The net exposure times listed above will result in spectra with S/N ratios of ~80 at 1356 Angstrom\ and ~50 at 1236 Angstrom\@. This sensitivity level will yield 5Sigma equivalent width detection thresholds of ~0.8 mAngstrom\ for the O I Lambda1356 line and ~1.1 mAngstrom\ for the Kr I Lambda1236 line. Since these features should have line strengths of at least a few mAngstrom\ in our targeted sightlines, this sensitivity will insure excellent measurements of the O and Kr column densities. The exposure times were calculated by inputing the measured IUE fluxes of each star into the STIS Spectroscopic Exposure Time Calculator and selecting the 0.1X0.03 aperture for HD37061 (due to its brightness) and the 0.2X0.09 aperture for the rest. According to the Calculator, none of the setups on our targets violate the MAMA bright object count rate limits. In calculating the number of orbits needed to complete our proposed observations of each star, we have allowed for all of the necessary acquisition and exposure overheads based on previous Cycle 7 STIS Phase II experience. Real Time Justification ----------------------- None. None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD27778 STAR, B3-B5 V-IV RA=4H 23M 59.76S +/- 0.002", J2000 V = 6.36 DEC=+24D 18' 03.7" +/- 0.002" B-V = 0.17 TYPE=B3V Comments: The coordinates are from the Hipparcos Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.000332 -0.01297 0.0 2 HD37021 STAR, B0-B2 V-IV RA=5H 35M 16.11S +/- 0.01", DEC= J2000 V = 7.96 -5D 23' 06.9" +/- 0.01" B-V = 0.24 TYPE=B0V Comments: The coordinates are from the Tycho Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.000062 0.00013 0.0 3 HD37061 STAR, B0-B2 V-IV RA=5H 35M 31.36S +/- 0.001", J2000 V = 6.83 DEC=-5D 16' 02.6" +/- 0.001" B-V = 0.18 TYPE=B1V Comments: The coordinates are from the Hipparcos Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.000118 0.00166 0.0 4 HD37903 STAR, B0-B2 V-IV RA=5H 41M 38.39S +/- 0.001", J2000 V = 7.81 DEC=-2D 15' 32.5" +/- 0.001" B-V = 0.10 TYPE=B1.5V Comments: The coordinates are from the Hipparcos Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.000105 0.00031 0.0 5 HD147888 STAR, B3-B5 V-IV RA=16H 25M 24.29S +/- 0.003", J2000 V = 6.74 DEC=-23D 27' 36.6" +/- 0.001" B-V = 0.32 TYPE=B3V Comments: The coordinates are from the Hipparcos Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. 8273( 4) - 09/22/99 13:50 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.000625 -0.02076 0.0 6 HD207198 STAR, Supergiant O RA=21H 44M 53.28S +/- 0.001", J2000 V = 5.96 DEC=+62D 27' 38.1" +/- 0.001" B-V = 0.31 TYPE=O9II Comments: The coordinates are from the Hipparcos Output Catalogue. Calculations using the on-line ETC and archival IUE large aperture SWP spectra for the E140H grating centered at 1271 A yield a count rate far below the MAMA bright object safety limits. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.000430 -0.00280 0.0 8273( 4) - 09/22/99 13:50 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD27778 STIS/C ACQ F25ND3 MIRROR 1 0.1 S ONBOARD ACQ FOR 11 CD ------------------------------------------------------------------------------------------------------------------------------------ 11 HD27778 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S ONBOARD ACQ FOR 12-13 CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 12 HD27778 STIS/F ACCUM 0.2X0.0 E140H 1271 2 855.0 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 13 HD27778 STIS/F ACCUM 0.2X0.0 E140H 1271 2 1230.0 UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 6] 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD37021 STIS/C ACQ F25ND3 MIRROR 1 0.4 S ONBOARD ACQ FOR 21 CD ------------------------------------------------------------------------------------------------------------------------------------ 21 HD37021 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.4 S ONBOARD ACQ FOR 22 CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 22 HD37021 STIS/F ACCUM 0.2X0.0 E140H 1271 2 845.0 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 7] 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 HD37061 STIS/C ACQ F25ND3 MIRROR 1 0.2 S ONBOARD ACQ FOR 31 CD ------------------------------------------------------------------------------------------------------------------------------------ 31 HD37061 STIS/C ACQ/PEA 0.2X0.0 G230LB 2375 1 5.0 S ONBOARD ACQ FOR 32 CD K 9 ------------------------------------------------------------------------------------------------------------------------------------ 32 HD37061 STIS/C ACQ/PEA 0.1X0.0 G230LB 2375 1 5.0 S ONBOARD ACQ FOR 33 CD K 3 ------------------------------------------------------------------------------------------------------------------------------------ 33 HD37061 STIS/F ACCUM 0.1X0.0 E140H 1271 2 550.0 S UV-MAM 3 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 8] 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 HD37903 STIS/C ACQ F25ND3 MIRROR 1 0.4 S ONBOARD ACQ FOR 41 CD ------------------------------------------------------------------------------------------------------------------------------------ 41 HD37903 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.4 S ONBOARD ACQ FOR 42 CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 42 HD37903 STIS/F ACCUM 0.2X0.0 E140H 1271 2 845.0 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 9] 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 HD147888 STIS/C ACQ F25ND3 MIRROR 1 0.2 S ONBOARD ACQ FOR 51 CD ------------------------------------------------------------------------------------------------------------------------------------ 51 HD147888 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.2 S ONBOARD ACQ FOR 52 CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 52 HD147888 STIS/F ACCUM 0.2X0.0 E140H 1271 2 855.0 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 10] 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 ------------------------------------------------------------------------------------------------------------------------------------ 60 HD207198 STIS/C ACQ F25ND3 MIRROR 1 0.1 S ONBOARD ACQ FOR 61 CD ------------------------------------------------------------------------------------------------------------------------------------ 61 HD207198 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 0.1 S ONBOARD ACQ FOR 62-63 CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 62 HD207198 STIS/F ACCUM 0.2X0.0 E140H 1271 2 950.0 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 63 HD207198 STIS/F ACCUM 0.2X0.0 E140H 1271 2 1265.0 UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 8273( 4) - 09/22/99 13:50 - [ 11] Summary Form for Proposal 8273 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.05ND 0.2X0.09 0.1X0.03 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 11 ONBOARD ACQ FOR 12-13 ONBOARD ACQ FOR 21 ONBOARD ACQ FOR 22 ONBOARD ACQ FOR 31 ONBOARD ACQ FOR 32 ONBOARD ACQ FOR 33 ONBOARD ACQ FOR 41 ONBOARD ACQ FOR 42 ONBOARD ACQ FOR 51 ONBOARD ACQ FOR 52 ONBOARD ACQ FOR 61 ONBOARD ACQ FOR 62-63 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140H G230LB ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD27778 HD37021 HD37061 HD37903 HD147888 HD207198 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1271 2375 ------------------------------------------------------------------------------------------------------------------------------------