7340( 9) - 08/10/99 10:21 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7340 Version: 9 Check-in Date: 09-Aug-1999 12:57:11 1.Proposal Title: The Distribution of Heavy Elements in Supernova Ejecta ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Jon Morse University of Colorado at Boulder CoI: P. Frank Winkler Middlebury College N CoI: William P. Blair Johns Hopkins University N CoI: Robert Kirshner Harvard University N ------------------------------------------------------------------------------------ 5. Abstract We propose to use the WFPC2 and STIS CCD to obtain maximum spatial resolution emission-line images of the young, oxygen- rich supernova remnants SN0540--69.3 in the LMC and E0102.2-- 7219 in the SMC. O IIILambda5007, S IILambdaLambda6724 and O IILambdaLambda3727 images of SN0540--69.3 will be used to characterize the ionization structure and distribution of chemically peculiar debris which ground- based imaging and spectroscopy have demonstrated to be present but cannot resolve. For E0102.2--7219, we will obtain an O IILambdaLambda3727 image which will be compared to our cycle 5 WFPC2 O IIILambda5007 image in order to determine the ionization structure in the SN debris. These data will provide another in the very limited set of benchmarks against which to measure models for nucleosynthesis in massive stars, excitation mechanisms in extremely metal-rich plasmas and the dynamics of supernova explosions. SN0540--69.3 holds special interest because it contains only the second known example (after the Crab) of an active pulsar and synchrotron nebula in a young supernova remnant. Furthermore, it is located < 400\ pc (projected) from SN 1987A and is part of the same extended complex of young stars. Since the SN explosion occurred < 1000\ yr ago, SN0540--69.3 is the closest to SN 1987A in both space and time of all known remnants in the LMC. ------------------------------------------------------------------------------------ 7340( 9) - 08/10/99 10:21 - [ 2] Observations Description ------------------------ Program: We request exposures with the STIS CCD and the Planetary Camera of WFPC2 in order to resolve compact structures in two oxygen-rich SNRs in the Magellanic Clouds. The ~ 0sec point05 pixel^-1 spatial scale corresponds to ~ 4 * 10^16 cm pixel^-1 at the distance of the Magellanic Clouds, equivalent to ~ 0sec point8 pixel^-1 at the distance of Cas A. Our WFPC2 imaging results for N132D (Morse Etal\ 1996) have demonstrated that this spatial scale is sufficient to resolve the fine-scale morphology, ionization structure and chemical fractionation in Magellanic Cloud SNRs. For SN0540-- 69.3 in the LMC, the most compact of the young SNRs in the Magellanic Clouds, we request exposures in O IILambdaLambda3727 with the STIS CCD and in O IIILambda5007, S IILambdaLambda6716, 6732, and nearby continuum bandpasses with the Planetary Camera of WFPC2. SN0540 is only 8'' in diameter, so is well-suited for study with the maximum spatial resolution possible. The central wavelengths of the emission lines in SN0540 are shifted by +370 kms\ relative to the local rest velocity of the LMC, and the widths of the lines are nearly 1500 kms\ FWHM (KMWB). Fortuitously, the central wavelengths of the WFPC2 F502N and F673N filters coincide almost precisely with the centers of the O III and (blended) S II lines in SN0540, and the filter widths are also well-matched. For O II, the STIS CCD F28X50OII filter (which has 6* higher throughput than the WFPC2 F375N filter) offers an 80Angstrom\ bandpass which easily contains all of the emission from the SNR. Also essential to the observation of SN0540 are off-band WFPC2 continuum images in order to distinguish stars and synchrotron emission from the emission- line filaments. We will use F547M, which provides the best wavelength match to the crucial O III line and passes no significant emission lines in SN0540. In the red, we will use F791W, where the synchrotron nebula is brightest (Chanan Etal\ 1984). We want F791W, rather than the generally preferred F814W, in order to exclude S IIILambdaLambda 9069, 9532, both of which are strong in SN0540 (KMWB). In the blue, the F336W filter avoids bright emission lines from the nebula and is the bandpass where the pulsed emission is brightest (Middleditch Etal\ 1987). E0102.2--7219 in the SMC has a diameter of 26'', an ideal size for the 28'' * 51'' field of view of the STIS CCD. We request exposures in O IILambdaLambda3727 emission through the F28X50OII filter to compare to our cycle 5 O IIILambda5007 image taken with the Planetary Camera and F502N filter (see Fig. 4). The velocity range in E0102 is ~ 6500 kms, which is well-matched by the 80Angstrom\ bandpass of the F28X50OII filter --- in fact, the STIS O II image will actually be better for elucidating the complete structure of E0102 because it will include essentially all the nebular emission whereas the narrow F502N bandpass excluded most of the high-velocity emission on the near and far sides of the expanding shell. In addition, the O IILambdaLambda3727 emission is the brightest of any line in the spectrum of E0102 between Lyman Alpha and 1 micron. (We will account for bandpass effects when we compare the F502N and F28X50OII images by using our Fabry-Perot velocity data to isolate the emission transmitted through each filter.) The stellar field in the vicinity of E0102 is not very dense and there is no sign of a synchrotron nebula in our F547M image; therefore, a continuum exposure is not necessary. Exposure times: We have used the formula N_el = 2.28 * 10^12Lambda T_maxF\ to estimate the expected count rates (e.g., see WFPC2 Handbook), where N_el\ is the number of electrons detected per second, T_max\ is the total system throughput for the relevant filter (from the WFPC2 and STIS Handbooks) at the wavelength Lambda\ (in Angstrom), and F\ is the observed integrated line flux (in ergs cm^-2 s^-1) per unit area on the sky being considered. We then calculated S/N ratios expected per PC1 or STIS CCD pixel, taking into account the expected number of CCD readouts due to CR-SPLITS and multi-orbit observations. centerline figure=tab1.ps, height=3.9in, width= The average O IIILambda5007 surface brightness (S_5007) for each remnant was measured from our longslit spectra. For SN0540, S_5007 ~ 1 * 10^-15 ergs cm^-2 s^-1 arcsec^-2, with (observed) line ratios O IILambdaLambda3727/O IIILambda5007 ~ 0.5 and S IILambdaLambda6724/O IIILambda5007 ~ 0.8. For E0102, S_5007 ~ 2.5 * 10^-15 ergs cm^-2 s^-1 arcsec^-2, and O IILambdaLambda3727/O IIILambda5007 ~ 2. As an example, we consider the O IIILambda5007 exposure of E0102 through the WFPC2 F502N filter. The total exposure time for our cycle 5 F502N exposure of E0102 was 1600s + (4 * 1400s) = 7200s, which took the better part of 3 orbits. The average surface brightness per PC1 pixel is 5* 10^-18 ergs cm^-2 s^-1 pixel^- 1, corresponding to a count rate of 3.1 * 10^-3 electrons s^- 1. Assuming a background sky count rate of ~ 30\ and including the dark count rates and 5 CCD readouts for CR- SPLITS, the S/N per pixel predicted for the 7200s exposure is 1.7. However, the filaments have been resolved into sharp features only a few pixels wide with peak brightnesses typically > 5 times higher than the average. In the brightest filaments we achieved S/N ratios > 7 per pixel, and in the faintest structures ~ 1.5 per pixel, as predicted using the above formula. Table 1 summarizes our expected count rates and S/N ratios for our requested exposures of SN0540 and E0102. These exposures roughly match the S/N achieved in the cycle 5 O III image of E0102 (Fig. 4), and were verified using the WFPC2 Exposure Time Calculator and sensitivity curves in the STIS instrument handbook. The imaging of SN0540 will require 2 spacecraft visits (to avoid the SAA). The short F336W, F547M and F791W continuum band exposures (2 * 300s) will be acquired during one additional orbit during the second visit. The grand total of requested orbits to study these rare but fundamental objects is 15, including guide star acquisitions and overheads. Real Time Justification ----------------------- The proposed observations of SN0540 and E0102 can be carried out in the CVZ, and doing so would increase the efficiency. We calculate that the data could be obtained in only 10 CVZ orbits, versus 15 normal ones. However, the observing windows for continous viewing are quite narrow, with fewer than 20 total orbits at each target position. We therefore assumed normal visibility of 58 minutes per orbit in our exposure time calculations. A large body of ground- and space- based supporting observations exists for each SNR: For SN0540, we have published low-resolution longslit spectrophotometry taken at the CTIO 4m telescope covering the wavelength region from 3500--9800Angstrom\ (KMWB). We have also obtained Fabry-Perot O IIILambda5007 velocity maps at the CTIO 4m that clearly show the expanding shell-like morphology (see Fig. 1). One of us (WPB) is analyzing HST GTO cycle 5 FOS spectra of a bright filament covering the wavelength region from Lyman Alpha to 8500Angstrom. However, from the marginal detection of only a few lines bluer than O IILambdaLambda3727, it appears that, like Cas A, SN0540 may be too reddened for high S/N UV spectroscopy --- thus emphasizing the importance of the optical data. NTT emission-line images have been published by Caraveo Etal\ (1992). Caraveo also led a cycle 5 program to image the HAlpha emission in SN0540; these images will be available in the HST archive in October 1996. ATCA radio maps have been published by Manchester Etal\ (1993a), and a ROSAT HRI image has been presented by Seward & Harnden (1994). Other ground-based observations studying the synchrotron nebula and pulsar are described in the Scientific Justification. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 7340( 9) - 08/10/99 10:21 - [ 3] Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7340( 9) - 08/10/99 10:21 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN0540-69.3 EXT-MEDIUM, SNR RA=5H40M11.213S +/- 0.1S, DEC=- 2000 V=+500 SURF(V) = 25.3+/-1 69D19'53.24" +/- 1" SURF-LINE(5007)=3+/-1e-15 Comments: Small, faint nebula, probably not visible on GASP image. Coords are from Cycle 5 WFPC2 PC1 images (see prop-ID 6120) using the STSDAS METRIC task. It would be beneficial to use the same ORIENTAT=-104.8 as was used for the 6120 program. 7340( 9) - 08/10/99 10:21 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PCS MODE F ORIENT 300.03850D TO 300.03850D 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 ------------------------------------------------------------------------------------------------------------------------------------ 101 SN0540-69.3 WFPC2 IMAGE PC1-FIX F673N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 107 SN0540-69.3 WFPC2 IMAGE PC1-FIX F673N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2800 S ------------------------------------------------------------------------------------------------------------------------------------ 108 SN0540-69.3 WFPC2 IMAGE PC1-FIX F673N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2800 S ------------------------------------------------------------------------------------------------------------------------------------ 7340( 9) - 08/10/99 10:21 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PCS MODE F SAME ORIENT AS 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 203 SN0540-69.3 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 204 SN0540-69.3 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2800 S ------------------------------------------------------------------------------------------------------------------------------------ 205 SN0540-69.3 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2800 S ------------------------------------------------------------------------------------------------------------------------------------ 206 SN0540-69.3 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 2800 S ------------------------------------------------------------------------------------------------------------------------------------ 207 SN0540-69.3 WFPC2 IMAGE PC1-FIX F791W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 400 S ------------------------------------------------------------------------------------------------------------------------------------ 208 SN0540-69.3 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ 209 SN0540-69.3 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5,CR-TOLERANCE=0.0 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 7340( 9) - 08/10/99 10:21 - [ 7] Summary Form for Proposal 7340 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE F ORIENT 300.03850D TO 300.03850D PCS MODE F SAME ORIENT AS 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F673N F502N F791W F336W F547M ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN0540-69.3 ------------------------------------------------------------------------------------------------------------------------------------