6154( 0) - 07/18/95 20:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6154 Version: ********** Check-in Date: ********** 1.Proposal Title: High-Resolution Observations of Highly Ionized Gas Toward the Halo Star HD 119608 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GTO/HRS 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Blair Savage University of Wisconsin-Madison CoI: Kenneth Sembach Massachusetts Institute of Technology Y CoI: Limin Lu California Institute of Technology N CoI: The GHRS Team Many Institutions N ------------------------------------------------------------------------------------ 6. Abstract We will use the echelle mode of the GHRS to obtain high-resolution, high S/N (40- 50:1) absorption line observations of the Si IV, C IV, and N V lines toward HD 119608, a halo star at 4.4 kpc in the direction l = 320, b = +43. We will compare the fully resolved high ion profiles to determine which ionization mechanisms give rise to highly ionized gas in the Galactic halo in this direction. In particular, we will search for 1) the narrow structured absorption associated with interface phenomena that gives rise to the ubiquitous N(C IV)/N(Si IV) ~ 3.5 ratio in the Galaxy and 2) a more highly ionized (and presumably hotter) type of gas that we have detected toward the inner Galaxy HD 167756 sight line. The relative fractions of the gas describe in (1) and (2) have implications for the thermal stability, filling fraction of hot gas, and energetics in the Galactic halo. ------------------------------------------------------------------------------------ 6154( 0) - 07/18/95 20:18 - [ 2] Observations Description ------------------------ We will use the Ech-A grating of the GHRS to provide 3.5 km/sec (FWHM) resolution spectra of the interstellar Si IV 1393, C IV 1548,1550, and N V 1238,1240 lines in the spectrum of HD 119608. All observations will be obtained in the large science aperture. FP-SPLIT=4, COMB=4, and STEP-PATT=7 will be used. We expect S/N = 45, 42, and 50 for Si IV, C IV, and N V, respectively. These S/N values are 1/2 diode values. Since we are quarter stepping, we will bin the data by two pixels (without loss of resolution). Real Time Justification ----------------------- No special scheduling requirements are necessary. Calibration Justification ------------------------- No special scheduling requirements are necessary. Additional Comments ------------------- No additional comments at this time. ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Kenneth Sembach*Center for Space Research*MIT 6-216*77 Massachusetts Avenue*Cambridge, MA 02139 Ship Via: UPS Email: sembach@sundoggie.mit.edu , ------------------------------------------------------------------------------------ 6154( 0) - 07/18/95 20:18 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD119608 STAR, B0-B2 III-I RA = 13H 44M 31.29S +/- 0.01S, J2000 V = +25 V = 7.50 DEC = -17D 56' 13.5" +/- 0.2" B-V = -0.07 +/- 0.05 F-CONT(1240) = 1.8 +/- 0.2 E-11 F-CONT(1550) = 2.3 +/- 0.2 E-11 Comments: Coordinates, flux are from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.000 -0.001 0.005 0.0 6154( 0) - 07/18/95 20:18 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Number exposures beginning with 10. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD119608 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN, 1 1.8S ONBOARD ACQ FOR 20-40 SEARCH-SIZE=3 Comments: Expect about 50,000 cnt/s using mirror N1. STEP-TIME = 0.2 seconds. Ok as long as BRIGHT=RETURN is used. ------------------------------------------------------------------------------------------------------------------------------------ 20 HD119608 HRS ACCUM 2.0 ECH-A 1240.9 FP-SPLIT=FOUR, 2 979.2S COMB=FOUR, STEP -PATT=7, DOPPLER=ON Comments: Lines = N V, Mg II ------------------------------------------------------------------------------------------------------------------------------------ 30 HD119608 HRS ACCUM 2.0 ECH-A 1391.8 FP-SPLIT=FOUR, 4 870.4S COMB=FOUR, STEP -PATT=7, DOPPLER=ON Comments: Lines = Si IV ------------------------------------------------------------------------------------------------------------------------------------ 40 HD119608 HRS ACCUM 2.0 ECH-A 1548.9 FP-SPLIT=FOUR, 5 1414.4S COMB=FOUR, STEP -PATT=7, DOPPLER=ON Comments: Lines = C IV ------------------------------------------------------------------------------------------------------------------------------------ 6154( 0) - 07/18/95 20:18 - [ 5] Summary Form for Proposal 6154 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 DOPPLER=ON STEP-PATT=7 COMB=FOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GTO/HRS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20-40 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 ECH-A ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD119608 ------------------------------------------------------------------------------------------------------------------------------------