8244( 5) - 04/05/00 15:19 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8244 Version: 5 Check-in Date: 05-Apr-2000 15:19:07 1.Proposal Title: Probing Stellar Ejecta in SN 1006 through UV Absorption Spectroscopy ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: P. Winkler Middlebury College CoI: Dr. Knox S. Long Space Telescope Science Institute Y CoI: Dr. Robert A. Fesen Dartmouth College N CoI: Dr. Andrew J. S. Hamilton University of Colorado N ------------------------------------------------------------------------------------ 5. Abstract The remnant of SN 1006 provides a unique opportunity to study ejecta from a Type Ia supernova through UV absorption spectroscopy. Absorption lines in the spectrum of the background Schweizer-Middleditch (SM) star have revealed the presence of cold Fe and Si with velocities up to 7000kms. These lines surely are due to ejecta, but extrapolation from a single line of sight to the entire remnant suggests a mass of Fe less than half the ~ 0.5\: Msun \ expected from a Type Ia supernova. A reliable inventory of the ejecta requires several such ``core samples'' through the remnant, but until now no other suitable background UV sources had been identified. A recent search has revealed four new background objects with which we propose to probe additional lines of sight through SN 1006: two quasars and two A0 stars. These are fortuituously well distributed about the 30'\ diameter shell---from only 2'\ away from the center (even closer than the SM star) to <=sssim 1'\ from the shell rim. In modest exposures with th e STIS we can obtain low-resolution spectra in both the near- and far-UV which will lead to a much fuller picture of the ejecta distribution and address the following questions: (1) Are the ejecta in diffuse expanding shells, or fragmented? In stratified layers, or mixed? (2) Where is the reverse shock which reheats the ejecta located? (3) Can the ``missing'' Fe from the Type Ia supernova be accounted for? ------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 2] Observations Description ------------------------ We propose low-resolution UV spectroscopy of all four of the new background UV sources we have identified within the (projected) shell of SN 1006, as detailed in Table 2, below. (No new observations are proposed for the SM star.) For three of them we should be able to obtain spectra with signal-to- noise >~ 10\ per resolution element in both the NUV and FUV in a modest number of orbits, and this is what we propose. For the fourth and faintest source, Q2 = QSO-1503- 4155, at z=1.025\ with V=19.5, we propose only NUV spectra, since the FUV is too photon-starved to give acceptable S/N in an observation of a few orbits. We have used the web-based STIS Exposure Time Calculator to estimate exposures, using our spectra and photometry to determine the source types and normalization. Since the sources are all more distant than the SM star and their reddening is not well determined, we have conservatively assumed a value E(B-V)=0.20, somewhat greater than the value of 0.12 measured fo r the SM star. (SN 1006 lies some 500 pc above the Galactic plane, so most extinction is probably in the foreground to the remnant.) We have calulated the minimum exposure to achieve S/N >~ 10\ per 2-pixel resolution element, and have then packed these exposures into orbits (using the relatively conservative guidelines in the STIS Handbook, chapter 9). We can do both FUV and NUV spectra of each source in the same visit, but in different orbits, saving the overhead of changing the grating during the visibility period. For SN 1006 at Delta = - 42degrees, the visibility period is 54 minutes. In the first orbit of a visit, Guide-star acquisition, standard target acquistion (no peak-up) and MAMA overhead require 7+6+8\ min, leaving 33 min = 1980 sec for exposure. In subsequent orbits, Guide-star reacquisition and MAMA overhead require 6+8\ min, leaving 40 min = 2400 sec. The exception is S2, which is bright enough that both FUV and NUV exposures can be obtained in a single orbit. None of the targets exceeds the MAMA bright-object limits (ST IS Handbook, p. 312). begincenter begintabularllrrrrc multicolumn6cTable 2. Proposed STIS Observations of SN 1006 Background Objects, & & multicolumn2cFUV (G140L) & multicolumn2cNUV (G230L) & Total , Source & Target Name & Exposure (s) & S/N (1400 Angstrom) & Exposure (s) & S/N (2370 Angstrom) & Orbits , Q1 & QSO-1504- 4152 & 6780\ \ \ \ & 10.7\ \ \ \ \ \ & 2400\ \ \ \ & 11.8\ \ \ \ \ \ & 4 , Q2 & QSO-1503-4155 & ---\ \ \ \ \ & ---\ \ \ \ \ \ \ & 13, 980\ \ \ \ & 10.3\ \ \ \ \ \ & 6 , S2 & STAR-1503-4209 & 1200\ \ \ \ & 18.3\ \ \ \ \ \ & 300\ \ \ \ & 18.4\ \ \ \ \ \ & 1 , S3 & STAR-1502-4207 & 7200\ \ \ \ & 10.7\ \ \ \ \ \ & 1980\ \ \ \ & 10.9\ \ \ \ \ \ & 4 , \medskip endtabular endcenter Real Time Justification ----------------------- None. We have already obtained good optical spectra of all the objects we propose to observe with STIS. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 3] Data Distribution Paper Products: YES Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 QSO-1504- GALAXY, QSO RA=15H 3M 33.93S +/- 1", DEC=- J2000 V = 18.3+/-0.2 4152 41D 52' 23.7" +/- 1" Comments: Quasar with z=0.335 behind the SNR 1006 2 QSO-1503- GALAXY, QSO RA=15H 2M 55.21S +/- 1", DEC=- J2000 V = 19.5+/-0.3 4155 41D 54' 29.8" +/- 1" Comments: QSO with z=1.025 behind the SN1006 3 STAR-1503- STAR, A0-A3 V-IV RA=15H 3M 29.5S +/- 1", DEC=-42D J2000 V = 13.5+/-0.1 4209 8' 54.8" +/- 1" Comments: A0V star thought to be behind SN1006 4 STAR-1502- STAR, A0-A3 V-IV RA=15H 2M 25.62S +/- 1", DEC=- J2000 V = 16.6+/-0.2 4207 42D 7' 6.6" +/- 1" Comments: A0V star thought to be behind SN1006 8244( 5) - 04/05/00 15:19 - [ 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 QSO-1504-41 STIS/C ACQ F28X50L MIRROR 1 10 S 52 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 QSO-1504-41 STIS/N ACCUM 52X0.2 G230L 2376 1 2400 S 52 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 QSO-1504-41 STIS/F ACCUM 52X0.2 G140L 1425 2 3000 S 52 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 6] Visit: 11 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 STAR-1503-4 STIS/C ACQ F28X50L MIRROR 1 0.5 S 209 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 STAR-1503-4 STIS/N ACCUM 52X0.2 G230L 2376 1 600 S 209 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 STAR-1503-4 STIS/F ACCUM 52X0.2 G140L 1425 1 1800 S 209 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 7] Visit: 21 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 STAR-1502-4 STIS/C ACQ F28X50L MIRROR 1 3 S 207 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 STAR-1502-4 STIS/N ACCUM 52X0.2 G230L 2376 1 2400 S 207 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 STAR-1502-4 STIS/F ACCUM 52X0.2 G140L 1425 2 3000 S 207 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 8] Visit: 31 Visit Priority: Visit Requirements: ON HOLD FOR 1-21 On Hold Comments: On Hold until after visits 1, 11, and 21 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 QSO-1503-41 STIS/C ACQ F28X50L MIRROR 1 10 S 55 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 QSO-1503-41 STIS/N ACCUM 52X0.2 G230L 2376 1 2400 S 55 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 QSO-1503-41 STIS/N ACCUM 52X0.2 G230L 2376 1 3000 S 55 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 9] Visit: 41 Visit Priority: Visit Requirements: ON HOLD FOR 1-21 On Hold Comments: On hold until after visits 1, 11, and 21 at which point we will decide where to place remaining time 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 QSO-1504-41 STIS/C ACQ F28X50L MIRROR 1 10 S 52 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 QSO-1504-41 STIS/F ACCUM 52X0.2 G140L 1425 1 2400 S 52 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 QSO-1504-41 STIS/F ACCUM 52X0.2 G140L 1425 1 3000 S 52 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 10] Visit: 51 Visit Priority: Visit Requirements: ON HOLD FOR 1-21 On Hold Comments: On hold until after visits 1, 21, and 31 at which point we will decide which on hold visit to activate 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 STAR-1502-4 STIS/C ACQ F28X50L MIRROR 1 3 S 207 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 STAR-1502-4 STIS/F ACCUM 52X0.2 G140L 1425 1 2400 S 207 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 STAR-1502-4 STIS/F ACCUM 52X0.2 G140L 1425 1 3000 S 207 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8244( 5) - 04/05/00 15:19 - [ 11] Summary Form for Proposal 8244 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD FOR 1-21 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G230L G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names QSO-1504-4152 STAR-1503-4209 STAR-1502-4207 QSO-1503-4155 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2376 1425 ------------------------------------------------------------------------------------------------------------------------------------