6034( 14) - 12/12/95 10:38 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6034 Version: 14 Check-in Date: ********** 1.Proposal Title: Physical conditions in ionized--neutral interfaces ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Jeremy Walsh Space Telescope European Co-ordinating Facility CoI: Michael Rosa Space Telescope European Coordinating N Facility CoI: Och Susanne European Southern Observatory N ------------------------------------------------------------------------------------ 6. Abstract High spatial resolution FOS spectra of the emission lines from ionized-neutral gas interfaces are proposed covering the UV- visible wavelength range. One partially ionized globule and one dense filament will be selected in the core of the nearest H II region, the Orion nebula. Spectra representing pencil beams with spatial resolution of 0.25" will be obtained at several positions across each target: centered on the condensation; at the edge in the very thin interface zone facing the ionizing cluster; in the tail behind the condensation and also in locations representative of the ionized surroundings. Emission line ratios so observed will be compared to dedicated nebular models treating, in detail and self-consistently, H II regions with neutral inclusions of arbitrary geometry, in order to derive the small- scale structure of the physical conditions -- N_e, T_e, ioniation parameter, fraction of neutral H, etc. Radiative transfer effects on the ionization of the shadowed zone by diffuse radiation, line of sight averaging of high and low ionization regimes to produce the integrated spectra of real nebulae and the time evolution of neutral inclusions will be among the topics studied on the basis of these observations. ------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 2] Observations Description ------------------------ The FOS Red side will be used with the five high dispersion gratings (G190H, G270H, G400H, G570H and G780H) covering the UV and optical region of the spectrum (1600-8300 A) to measure the strength of emission lines over and in the near vicinity of neutral inclusions in the Orion nebula. The aperture B-2 aperture (projected diameter 0.26") will be employed to achieve high spatial resolution to ensure as little contamination as possible from neighbouring emission. Two targets will be observed: one of the Laques & Vidal (1979) partially ionized globules in the vicinity of the Trapezium stars (No. 2, referred to as LV2) and one of the S II strong filaments selected from the HST images of Orion. For the LV globule, spectra will be obtained at the bright ionization margin, at the centre of the globule, and in the tail of the globule. For the filament, spectra will be obtained on the filament ridge as seen in NII and at a position nearby representative of the average nebular background for that filament. The spectra off the targets are required to determine the background contribution to the targets and an indication of the small scale changes in emission line properties against which the neutral- ionized interface spectra must be compared. Employing the 0.26" aperture on the WFPC2 ERO images (u2440101t-u2440104t), combined with the flux measurements of Meaburn et al (1993), and scaling by the mean line ratios of the Orion emission line spectrum near the Trapezium region (Pos. 2b of Peimbert & Torres-Peimbert, MNRAS 179, 217 (1977), Pos 2uv of Torres-Peimbert+, APJ 238, 133 (1980)) gives the following estimated HAlfa line fluxes and detected counts in the aperture: Position F(HAlfa) Detected Cnts/s G570H LV2 core 3.0E- 13 100 LV2 head 2.9E-13 100 LV2 tail 2.8E-13 95 Filament 2.6E-13 90 Near filament 2.0E-13 68 For the weak line diagnostics we need to go to at least as faint as the OIII 4363 A line, i.e. 0.0017 of HAlfa. For accurate T_e determination we need an SNR of better 10 for that strengths, so >=100 counts. This implies 200-1000s per wavelength range for G400H and G570H, 100-200s for the UV gratings (for the important C II and C III lines), and 50-100s for the less sensitive G780H grating. The G780H range has the important O II 7320,7330 A line as well as HAlpha, N II 6548,6583 A, and SII 6718,6730 A lines. Thus between 500s and 2000s are required per position, depending on the anticipated ionization conditions. The 6 orbits allocated permit a total of 5600s science exposure distributed among 5 positions. The initial PhaseI request asked for a total 48000s to to do 5 positions on LV2 and 3 on the filament. Figure caption: HAlpha plate showing the Lacques--Vidal sources near the Trapezium cluster (Vidal 1982, in Symposium on the Orion Nebula to honor Henry Draper, Glassgold et al (eds), Ann. NY Acad. Sci. Vol 395, p 176). South is up and East is to the right. Exact positions of the positions across the targets and the required offsets from a nearby faint star, which will be used for centering with peakup acquisition, have been determined from public WFPC2 data sets. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M42-OFFSET- STAR RA=05H 35M 17.010S +/- 2000 V = 14.8 B-V = 0.30 STAR 0.02S,DEC=-05D 23' 34.32" +/- 0.3" Comments: Offset star for peak-up and offsets to targets. Vmag and position from WFPC2 u2440103t[4] (NEW PLATE SCALE=0.04554), color unknown, assumed F0 type. Revised coordinates correspond to average of zeroing the frame on SAO pos of THETA1C, the catalogue position Jones/Walker AJ 95,1755 (1988), and direct measurement on WFPC1 frame W0O70A01T. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2. 0.0 0.0 0.0 2 M42-LV2-CORE ISM, KNOT RA-OFF=-0.301S+/- 0.002S,DEC- 2000 SURF-LINE(6563)=6.0+/-0.5e-12 OFF=17.70"+/- 0.03",FROM 1 Comments: Peak of Lacques-Vidal Globule 2. Offset measured from WFPC2 u2440103t[4]. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2 0.0 0.0 0.0 3 M42-LV2-TAIL ISM, KNOT RA-OFF=-0.272S+/- 0.002S,DEC- 2000 SURF-LINE(6563)=5.8+/-0.5e-12 OFF=18.35"+/- 0.03",FROM 1 Comments: 1.0" NW from peak of Lacques-Vidal Globule 2. Offset measured from WFPC2 u2440103t[4]. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2 0.0 0.0 0.0 4 M42-LV2-HEAD ISM, KNOT RA-OFF=-.315S+/- 0.002S,DEC- 2000 SURF-LINE(6563)=5.7+/-0.5e-12 OFF=17.39"+/- 0.03",FROM 1 Comments: .6" SE from peak of Lacques-Vidal Globule 2. Offset measured from WFPC2 u2440103t[4]. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2 0.0 0.0 0.0 5 M42-FILAMENT ISM, FILAMENT RA-OFF=-0.938S+/- 0.002S,DEC- 2000 SURF-LINE(6563)=5.2+/-0.5e-12 -PEAK OFF=-35.95"+/- 0.03",FROM 1 Comments: Local peak of narrow filament in core of M42. Offset measured from WFPC2 u2440103t[4]. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2 0.0 0.0 0.0 6 M42-FILAMENT ISM, FILAMENT RA-OFF=-0.837S+/- 0.002S,DEC- 2000 SURF-LINE(6563)=4.1+/-0.5e-12 -BACK OFF=-35.60"+/- 0.03",FROM 1 Comments: Background position 1.5" E of filament. Offset measured from WFPC2 u2440103t[4]. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1994.2 0.0 0.0 0.0 6034( 14) - 12/12/95 10:38 - [ 5] Visit: 01 Visit Requirements: ON HOLD On Hold Comments: Position of TARGET 1 (offset star) to be checked, since it is obtained as offset from overexposed star THET1 ORIC on WFPC2. THET1 ORIC is also in GSC but has uncertain position due to overexposure. Discrepancies WFPC2-GSC-SAO -PPM amount to several arcseconds. To be resolved till April 1995. Offset star is likely in Orion cluster catalog (Parenago). 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 M42-OFFSET- FOS/RD ACQ/PEA 4.3 MIRROR SCAN-STEP- 1 1S ONBOARD ACQ FOR 2 STAR K X=2.3,SCAN-STEP -Y=1.2,SEARCH- SIZE-X=2,SEARCH -SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 2 M42-OFFSET- FOS/RD ACQ/PEA 1.0 MIRROR SCAN-STEP- 1 1S ONBOARD ACQ FOR 3 STAR K X=0.61,SCAN- STEP- Y=0.61,SEARCH- SIZE-X=6,SEARCH Comments: -SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 M42-OFFSET- FOS/RD ACQ/PEA 0.5 MIRROR SCAN-STEP- 1 1S ONBOARD ACQ FOR 4 STAR K X=0.29,SCAN- STEP- Y=0.29,SEARCH- SIZE-X=3,SEARCH Comments: -SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 4 M42-OFFSET- FOS/RD ACQ/PEA 0.3 MIRROR SCAN-STEP- 1 3S ONBOARD ACQ FOR 10-54 STAR K X=0.11,SCAN- STEP- Y=0.11,SEARCH- SIZE-X=4,SEARCH Comments: -SIZE-Y=4 ------------------------------------------------------------------------------------------------------------------------------------ 10 M42-LV2- FOS/RD ACCUM 0.3 G190H 1 60S CORE ------------------------------------------------------------------------------------------------------------------------------------ 11 M42-LV2- FOS/RD ACCUM 0.3 G270H 1 40S CORE ------------------------------------------------------------------------------------------------------------------------------------ 12 M42-LV2- FOS/RD ACCUM 0.3 G400H 1 200S CORE ------------------------------------------------------------------------------------------------------------------------------------ 13 M42-LV2- FOS/RD ACCUM 0.3 G570H 1 200S CORE ------------------------------------------------------------------------------------------------------------------------------------ 14 M42-LV2- FOS/RD ACCUM 0.3 G780H 1 60S CORE ------------------------------------------------------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 20 M42-LV2- FOS/RD ACCUM 0.3 G190H 1 60S TAIL ------------------------------------------------------------------------------------------------------------------------------------ 21 M42-LV2- FOS/RD ACCUM 0.3 G270H 1 30S TAIL ------------------------------------------------------------------------------------------------------------------------------------ 22 M42-LV2- FOS/RD ACCUM 0.3 G400H 1 230S TAIL ------------------------------------------------------------------------------------------------------------------------------------ 23 M42-LV2- FOS/RD ACCUM 0.3 G570H 1 229S TAIL ------------------------------------------------------------------------------------------------------------------------------------ 24 M42-LV2- FOS/RD ACCUM 0.3 G780H 1 100S TAIL ------------------------------------------------------------------------------------------------------------------------------------ 30 M42-LV2- FOS/RD ACCUM 0.3 G190H 1 100S HEAD ------------------------------------------------------------------------------------------------------------------------------------ 31 M42-LV2- FOS/RD ACCUM 0.3 G270H 1 80S HEAD ------------------------------------------------------------------------------------------------------------------------------------ 32 M42-LV2- FOS/RD ACCUM 0.3 G400H 1 220S HEAD ------------------------------------------------------------------------------------------------------------------------------------ 33 M42-LV2- FOS/RD ACCUM 0.3 G570H 1 200S HEAD ------------------------------------------------------------------------------------------------------------------------------------ 34 M42-LV2- FOS/RD ACCUM 0.3 G780H 1 80S HEAD ------------------------------------------------------------------------------------------------------------------------------------ 40 M42- FOS/RD ACCUM 0.3 G190H 1 200S FILAMENT- PEAK ------------------------------------------------------------------------------------------------------------------------------------ 41 M42- FOS/RD ACCUM 0.3 G270H 1 85S FILAMENT- PEAK ------------------------------------------------------------------------------------------------------------------------------------ 42 M42- FOS/RD ACCUM 0.3 G400H 1 666S FILAMENT- PEAK ------------------------------------------------------------------------------------------------------------------------------------ 43 M42- FOS/RD ACCUM 0.3 G570H 1 1000S FILAMENT- PEAK ------------------------------------------------------------------------------------------------------------------------------------ 44 M42- FOS/RD ACCUM 0.3 G780H 1 100S FILAMENT- PEAK ------------------------------------------------------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 50 M42- FOS/RD ACCUM 0.3 G190H 1 200S FILAMENT- BACK ------------------------------------------------------------------------------------------------------------------------------------ 51 M42- FOS/RD ACCUM 0.3 G270H 1 58S FILAMENT- BACK ------------------------------------------------------------------------------------------------------------------------------------ 52 M42- FOS/RD ACCUM 0.3 G400H 1 666S FILAMENT- BACK ------------------------------------------------------------------------------------------------------------------------------------ 53 M42- FOS/RD ACCUM 0.3 G570H 1 1000S FILAMENT- BACK ------------------------------------------------------------------------------------------------------------------------------------ 54 M42- FOS/RD ACCUM 0.3 G780H 1 100S FILAMENT- BACK ------------------------------------------------------------------------------------------------------------------------------------ 6034( 14) - 12/12/95 10:38 - [ 8] Summary Form for Proposal 6034 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-X=2.3 SCAN-STEP-Y=1.2 SEARCH-SIZE-X=2 SEARCH-SIZE-Y=5 SEARCH-SIZE-Y=2 SEARCH-SIZE-Y=3 SEARCH-SIZE-Y=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4 ONBOARD ACQ FOR 10-54 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G190H G270H G400H G570H G780H ------------------------------------------------------------------------------------------------------------------------------------ Target Names M42-OFFSET-STAR M42-LV2-CORE M42-LV2-TAIL M42-LV2-HEAD M42-FILAMENT-PEAK M42-FILAMENT-BACK ------------------------------------------------------------------------------------------------------------------------------------