7763( 5) - 11/17/98 15:47 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7763 Version: 5 Check-in Date: 17-Nov-1998 15:47:06 1.Proposal Title: A Test For Products of Oxygen Burning in the Crab Nebula ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Gordon Macalpine University of Michigan CoI: William Blair The Johns Hopkins University N CoI: Kris Davidson University of Minnesota N CoI: Robert Fesen Dartmouth College N CoI: Richard Henry University of Oklahoma N CoI: Stephen Lawrence University of Mexico N CoI: Alan Uomoto The Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract Young supernova remnants are excellent laboratories for investigating how stars make elements, and the Crab Nebula can provide unique information about the supernova process and associated heavy element production. Existing evidence indicates that the progenitor star initially contained 9-11 solar masses. Some calculations suggest that oxygen burning does not take place in such stars, whereas other models support off-center ignition of oxygen. It is important to determine how far the nuclear reactions progressed and to know whether the nebular gas is significantly contaminated by products of oxygen burning, such as sulfur. In conjunction with an optical and theoretical investigation of regions showing unusually strong [S II] 6716, 6731 lines, a simple test will be performed to determine whether this emission is a result of filament optical depth characteristics or of significantly increased sulfur abundance. In the former case, the intensities of the [S II] lines and Mg II 2798 would be directly correlated, whereas they would be strongly anticorrelated if products of oxygen burning are significantly enhanced in the nebula. ------------------------------------------------------------------------------------ 7763( 5) - 11/17/98 15:47 - [ 2] Observations Description ------------------------ We will use the STIS/CCD for measuring near-ultraviolet line emission at a selected location in the Crab Nebula. That location, designated NGC1952-HS.SPOT (high-sulfur spot), is to be acquired by offsetting from WMstar18 (V = 16.4, B- V = 1.3, offset of about 20 arcsec). The WMstars are defined in Wyckoff and Murray (1977, MNRAS, 180, 717). The appropriate dispersing element is G230LB, and the best trade-off between resolution and S/N within allowable time limitations is obtained with the 52x0.5 slit. In addition, we will use the STIS/CCD combination with the G430L grating for a relatively short exposure to provide overlap with existing ground-based optical spectra. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7763( 5) - 11/17/98 15:47 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR- STAR, UNDESIGNATED RA = 5H 34M 33.07S +/- 0.01S, J2000 V = 16.4+/-0.2 053433+21595 DEC = +21D 59' 51.8" +/- 0.15", B-V = 1.3+/-0.2 1-OFFSET PLATE-ID = 000M Comments: THIS IS STAR 18 OF WYCKOFF AND MURRAY 1977, MNRAS, 180, 717. MAGNITUDE AND COLOR ARE ESTIMATES BASED ON CCD IMAGES. 2 NGC1952- ISM, SNR, EJECTA RA-OFF = +1.30S +/- 0.01S, DEC- J2000 SURF(V) = 20.0+/-1.0 HS.SPOT OFF = -9.8" +/- 0.15", FROM 1 E(B-V) = 0.47+/-0.03 F-LINE(2800)=2+/-3e-16 W-LINE(2800)=1.0+/-0.5 F-LINE(4340)=5+/-1e-16 W-LINE(4340)=1.0+/-0.5 Comments: 3" x 2" REGION IN THE CRAB NEBULA WITH VERY STRONG OPTICAL [S II] EMISSION. SURFACE V BRIGHTNESS IS ESTIMATE BASED ON CCD IMAGES. MG II 2800 LINE FLUX IS LOWER LIMIT BASED ON PHOTOIONIZATION MODELS, TAKING INTO ACCOUNT REDDENING AND DEPLETION ON GRAINS. 7763( 5) - 11/17/98 15:47 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 50D TO 60D On Hold Comments: Additional Comments: A 180D FLIP IN SLIT ORIENTATION WOULD BE EQUALLY ACCEPTABLE. 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-053433 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 5 S ONBOARD ACQ FOR 2-7 +215951-OFF CD P SET ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1952-HS. STIS/C ACCUM 52X0.5 G430L 4300 BINAXIS1=2,BINAXIS2=2,CR-SPLIT=3 1 2304 S NO SPLIT SPOT CD Comments: EXPOSURE TIME SHOULD PRODUCE S/N OF ROUGHLY 12 FOR 4340 LINE, ASSUMING 2" SUMMING ALONG SLIT. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1952-HS. STIS/C ACCUM 52X0.5 G230LB 2375 BINAXIS1=2,BINAXIS2=2 1 2700 S NO SPLIT SPOT CD Comments: TOTAL OF TIMES IN EXPOSURES 3-7 WILL PROVIDE S/N OF ROUGHLY 5 FOR 2800 LINE LOWER LIMIT, ASSUMING 2" SUMMING ALONG SLIT. ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1952-HS. STIS/C ACCUM 52X0.5 G230LB 2375 BINAXIS1=2,BINAXIS2=2 1 2815 S NO SPLIT SPOT CD ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1952-HS. STIS/C ACCUM 52X0.5 G230LB 2375 BINAXIS1=2,BINAXIS2=2 1 2815 S NO SPLIT SPOT CD ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC1952-HS. STIS/C ACCUM 52X0.5 G230LB 2375 BINAXIS1=2,BINAXIS2=2 1 2815 S NO SPLIT SPOT CD ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC1952-HS. STIS/C ACCUM 52X0.5 G230LB 2375 BINAXIS1=2,BINAXIS2=2 1 2815 S NO SPLIT SPOT CD ------------------------------------------------------------------------------------------------------------------------------------ 7763( 5) - 11/17/98 15:47 - [ 5] Summary Form for Proposal 7763 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.5 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=3 BINAXIS2=2 BINAXIS1=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 50D TO 60D ONBOARD ACQ FOR 2-7 NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L G230LB ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-053433+215951-OFFSET NGC1952-HS.SPOT ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 2375 ------------------------------------------------------------------------------------------------------------------------------------