7349( 4) - 01/26/99 11:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7349 Version: 4 Check-in Date: 26-Jan-1999 11:18:21 1.Proposal Title: Far UV Echelle Spectroscopy of Ejecta in SN1006 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Andrew Hamilton University of Colorado CoI: Robert A. Fesen Dartmouth College N CoI: William P. Blair The Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract The ejecta of the remnant of the Type Ia Supernova 1006 can be studied in a unique way, through the broad, high velocity absorption features it causes in the spectrum of an OB subdwarf star fortuitously located behind the remnant. We propose far UV echelle spectroscopy, with STIS E140M, of this OB subdwarf, and also of the subwarf PG 0839+399 to provide a comparable stellar template spectrum. The intent is to obtain detailed line profiles, at a resolution 30 times that of the existing FOS spectra, of the redshifted (~ +6000 kmps) Si II 1260, 1304 and 1527 Angstrom, Si III 1206 Angstrom, and Si IV 1400 Angstrom absorption features caused by silicon ejecta in SN1006. The scientific goals are: (1) to determine how sharp is the red edge (at +7070 kmps) on the strong Si II 1260 Angstrom absorption feature, and thereby to test the hypothesis that this edge represents the free expansion velocity of the reverse shock; (2) to resolve the discrepancies in the FOS spectrum between the Si II 1260, 1304 and 1527 Angstrom line profiles, which may be caused by stellar features; (3) to compare the line profiles and column densities of Si II, Si III, and Si IV, which reveal the mass and distribution of silicon in the ejecta, and which constrain models for the shocked and unshocked ejecta; (4) to place constraints on the presence of other high velocity absorption, notably blue-shifted Si IV 1400 Angstrom, which is expected at a low level. ------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 2] Observations Description ------------------------ We propose STIS echelle spectroscopy of the SM star, and of the comparison star PG 0839+399, with the E140M grating on the FUV-MAMA. To achieve a S/N ratio of 10 per resolution element will require 8 orbits for the SM star, and 1 orbit for PG 0839+399, as shown below. A S/N ratio of 10 per resolution element in the MAMA E140M spectrum would correspond to a S/N ratio of 60 if binned to the resolution of the FOS spectrum (R = Lambda / 2 Delta Lambda = 45800 for E140M versus 1300 for FOS, according to the STIS Handbook page 34 and Phase 1 Instructions Appendix D.3). Thus we regard a S/N ratio of 10 as minimal if the STIS spectrum of the SM star is to be a quantitative improvement over the FOS spectrum shown in Figure 1. For the SM star, achieving a S/N ratio of 10 per resolution element in the continuum between 1200 and 1500 Angstrom requires an exposure time of 2 * 10^4 seconds with the 0.2'' * 0.2'' slit, according to the WWW STIS exposure calculator using the calibrated FOS G130H spectrum, Figure 1, as input. The peak count rate is 0.008 cts/sec/pix at Ly-alpha, the global rate is 94 cts/sec, and no brightness limit is violated. Noise is dominated by the dark current, which produces count rates approximately 1/10 of the signal (STIS Handbook, page 70 and following). For the SM star, orbital visibility at Delta = - 42 degrees is 54 minutes (Phase 1 instructions, Table 7, page 54), sky background being negligible. For the first orbit, initial guide star acquisition using the F28X50LP aperture (STIS Handbook, page 111), target acquisition, peakup, and MAMA exposure (wavecal) overheads take 9+8+10+8 = 35 minutes (STIS Handbook, page 124 and following), leaving 19 minutes of science observing time. In subsequent orbits, guide star reacquisition and MAMA overheads take 6+1 = 7 minutes, leaving 47 minutes. A repeakup at the start of the 4th orbit may be desirable, taking 10 minutes. A total of 8 orbits on the SM star will then yield 338 minutes = 2.0 * 10^4 seconds of observing time, yielding the desired S/N = 10. For PG 0839+399, whose flux is 17 times that of the SM star at the relevant wavelengths, achieving the same S/N = 10 per resolution element requires 900 seconds, according to the WWW STIS calculator. For PG 0839+399, orbital visibility at Delta = +40 degrees is also 54 minutes. After overhead, one orbit will allow 19 minutes = 1140 seconds of observing time, yielding S/N = 11 per resolution element. No brightness limit is violated. Real Time Justification ----------------------- None. Calibration Justification ------------------------- None. Additional Comments ------------------- ------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 3] Data Distribution Paper Products: Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-1503- STAR, SDO, Supernova, RA=15H 02M 53.18S +/- .1S, DEC=- 2000 V = 16.74+/-0.02 4159 Supernova Type Ia, ISM, 41D 59' 17.7" +/- 1", PLATE- B-V = -0.14+/-0.02 SNR, Absorption Line ID=02F5 U-B = -1.07+/-0.03 System - Galactic V-R = -0.12+/-0.04 E(B-V) = 0.119+/-0.01 F-CONT(1260)=4.1+/-0.1e-14 F-LINE(1216)=7.3+/-0.2e-12 W-LINE(1216)=2.4+/-0.2 TYPE=SDO 2 PG-0839+399 STAR, SDO RA=08H 43M 12.7S +/- .1S, 2000 V = 14.39+/-0.05 DEC=39D 44' 49.9" +/- 1", PLATE- B-V = -0.29+/-0.05 ID=00XV E(B-V) = 0.05+/-0.05 F-CONT(1260)=6.5+/-0.2e-13 F-LINE(1216)=8+/-4e-12 W-LINE(1216)=2.4+/-1 TYPE=SDO 7349( 4) - 01/26/99 11:18 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-1503-4 STIS/C ACQ F28X50L MIRROR 1 4 S ONBOARD ACQuisition FOR 159 CD P 2-3 ------------------------------------------------------------------------------------------------------------------------------------ 2 STAR-1503-4 STIS/F ACCUM 0.2X0.2 E140M 1425 1 39 M 159 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-1503-4 STIS/F ACCUM 0.2X0.2 E140M 1425 3 49 M 159 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-1503-4 STIS/C ACQ F28X50L MIRROR 1 4 S ONBOARD ACQuisition FOR 159 CD P 2-3 ------------------------------------------------------------------------------------------------------------------------------------ 2 STAR-1503-4 STIS/F ACCUM 0.2X0.2 E140M 1425 1 39 M 159 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-1503-4 STIS/F ACCUM 0.2X0.2 E140M 1425 3 49 M 159 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 PG-0839+399 STIS/C ACQ F28X50L MIRROR 1 1 S ONBOARD ACQuisition FOR 2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 PG-0839+399 STIS/F ACCUM 0.2X0.2 E140M 1425 1 38 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7349( 4) - 01/26/99 11:18 - [ 8] Summary Form for Proposal 7349 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQuisition FOR 2-3 ONBOARD ACQuisition FOR 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-1503-4159 PG-0839+399 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------