8110( 5) - 10/24/00 17:39 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8110 Version: 5 Check-in Date: 24-Oct-2000 17:38:34 1.Proposal Title: Supernova Remnants in a Cloudy Interstellar Medium ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: You-Hua Chu University of Illinois at Urbana - Champaign CoI: Ms. Rosa Williams University of Illinois N CoI: Dr. John Dickel University of Illinois N CoI: Dr. Adeline Caulet University of Illinois N CoI: Mr. Robert Klinger University of Illinois N CoI: Dr. Eric Gotthelf Goddard Space Flight Center N ------------------------------------------------------------------------------------ 5. Abstract Small cloudlets in the interstellar medium (ISM) may have a marked effect on the physical structure and evolution of supernova remnants (SNRs). The effects of evaporating cloudlets in a SNR interior have been modeled and are an important factor leading t o McKee & Ostriker's three-phase model of the ISM. The cloudlets themselves are only now becoming observable through high-resolution instruments such as the Hubble Space Telescope's Wide Field and Planetary Camera (WFPC2). We propose WFPC2 observations o f the three SNRs, N49, N206, and N63A, which appear to be the best candidates for the examination of the physical structure of SNRs in a cloudy ISM. These WFPC2 images can be combined with complementary observations in other wavelength regimes to identify cloudlets inside remnants; trace SNR shock fronts; determine the physical parameters of interior cloudlets and compare them to those of the hot interior; and investigate the evaporation of shocked cloudlets into the hot cav it ies of the SNRs. ------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 2] Observations Description ------------------------ We request eight orbits with the F656N (H Alpha), F673N (ionS2), and F502N (ionO3) filters (Table 1). In each case, we have included the overtime required for the exposure in the calculation of the number of orbits required. The signal-to-noise ratios p er pixel given below should be considered as lower limits on the expected data quality. We expect no problems with saturation, as the maximum count level per pixel for any of these observations is 3.5\ begintableh beginminipage5.75in captionProposed WFPC 2 Filters and Exposure Times begintabularlccccccccc SNR & multicolumn3cH Alpha & multicolumn3c\ionS2 & multicolumn3c\ionO3 , & t_exp & orbits & S/N & t_exp & orbits & S/N & t_exp & orbits & S/N , N49 & 1300s & 0.5 & 30 & 1400s & 0.5 & 20 & 3000s & 1 & 20 , N206: pointing 1 & 3000s & 1 & 11 & 3000s & 1 & 7.6 & 6000s & 2 & 5.7 , N206: pointing 2 & 3000s & 1 & 11 & -- & -- & -- & -- & -- & -- , N63A & -- & -- & -- & -- & -- & -- & 3000s & 1 & 5.5 , endtabular endmin ip age endtable For N49, we request 1 orbit of WFPC2 observations, equally divided between the H Alpha\ (F656N) and ionS2 (F673N) filters. Another orbit will cover the ionO3 (F502N) observations for this object. From ground- based observations of N49, using the 1.5m telescope at CTIO, we estimate an average H Alpha\ surface brightness of 4.5 times10^-14 erg cm^-2 s^-1 arcsec^-2. Using the on-line Exposure Time Calculator provided by STSCI, this suggests that an exposure of 1300 seconds with filter F656N wil l be sufficient to produce a signal-to-noise ratio per pixel of about 30 over most of the remnant. A study by Vancura et al. (1992, ApJ, 394, 158) gives a ionS2/H Alpha\ ratio of ~0.4 and a ionO3/H Alpha\ ratio of ~0.5 for N49. If we take these values as representative, then a signal-to- noise ratio of 20 requires exposure times of 1400 seconds with the F673N filter. The same signal-to-noise of 20 requires 3000 seconds with the F502N filter. N206 is almost 3' in diameter, he nc e two pointings are needed to map the entire remnant. We plan to map N206 in the HAlpha line in order to determine the spectrum of cloud sizes over the entire remnant. The ionO3 and ionS2 spectral information is needed only for one of the two pointings. We request 1 WFPC2 orbit for each of two pointings of N206 with the H Alpha\ (F656N) filter; 1 orbit for ionS2 (F673N) observations of one pointing; and 2 orbits to cover the ionO3 (F502N) observations of the same pointing. The 1.5m CTIO observations of N206 give an average H Alpha\ surface brightness of 3.2 * 10^-15 erg cm^-2 s^-1 arcsec^-2; a full orbit exposure of 3000 seconds with WFPC2 (F656N) thereby yields an expected signal-to-noise ratio of 11. The orbits for ionS2 and ionO3 will use the same po inting as the first H Alpha\ orbit. Using ~0.5 for the ionS2/H Alpha\ and ionO3/H Alpha\ ratios, we find that a full orbit exposure of 3000 seconds gives a signal-to-noise ratio of 7.6 for ionS2, and a 2 orbit exposure of 6 00 0 seconds would give a signal- to- noise ratio of 5.7 for ionO3. For N63A, we request 1 orbit of WFPC2 observations using the ionO3 filter (F502N). Our previous observations give an average H Alpha\ surface brightness of 1.5 times10^-14 erg cm^-2 s^-1 arc sec^- 2 for the SNR and surrounding ionH2 region. Using an approximate ionO3/H Alpha\ ratio of 0.2 based on observations by Levenson et al. (1995, AJ, 110, 739), we find that an exposure time of 3000 seconds gives a signal-to-noise ratio of 5.5 for this re gion. Higher ionO3/H Alpha\ ratios of 0.5 and 1 give signal-to- noise ratios of 10 and 16, respectively, for this same exposure time. Real Time Justification ----------------------- None. No supporting observations affect HST scheduling. Calibration Justification ------------------------- Additional Comments ------------------- N49 was observed in H-alpha by Davidsen with WFPC1 (GTO-1048) but the image quality is not good enough for the high resolution and sensitivity needed for the study of small cloudlets in the SNR (Dickel et al. 1995). N49 was also observed with WFPC2 (GTO-6 827) by Kulkarni in a series of wide-band and medium -band filters, but these continuum images are not sensitive to the shocked structures which we wish to study; emission-line images are required. ------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 N49 EXT-MEDIUM RA=05H 26M 2.5S +/- 1S, DEC=-66D J2000 SURF-LINE(6563)=4.5+/-0.45e-14 4' 45" +/- 1" Coordinate Source: Comments: See "General Comments" 2 N206-POS1 EXT-MEDIUM, SNR RA=05H 31M 54.5S +/- 1S, DEC=- J2000 SURF-LINE(6563)=3.2+/-0.32e-15 71D 0' 25" +/- 1" 3 N206-POS2 EXT-MEDIUM, SNR RA=05H 31M 55.8S +/- 1S, DEC=- J2000 SURF-LINE(6563)=3.2+/-0.32e-15 71D 0' 8" +/- 1" 4 N63A EXT-MEDIUM, SNR RA=05H 35M 38.2S +/- 1S, DEC=- J2000 SURF-LINE(6563)=1.5+/-0.15e-14 66D 2' 37.5" +/- 1" 8110( 5) - 10/24/00 17:39 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 220D TO 230D 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 N49 WFPC2 IMAGE WF3-FIX F656N 1 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 20 N49 WFPC2 IMAGE WF3-FIX F673N 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 30 N49 WFPC2 IMAGE WF3-FIX F502N 1 1600 S ------------------------------------------------------------------------------------------------------------------------------------ 40 N49 WFPC2 IMAGE WF3-FIX F502N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 40D TO 50D 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 N206-POS1 WFPC2 IMAGE PC1-FIX F656N 1 1500 S ------------------------------------------------------------------------------------------------------------------------------------ 20 N206-POS1 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 30 N206-POS1 WFPC2 IMAGE PC1-FIX F673N 1 1500 S ------------------------------------------------------------------------------------------------------------------------------------ 40 N206-POS1 WFPC2 IMAGE PC1-FIX F673N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 50 N206-POS1 WFPC2 IMAGE PC1-FIX F502N 1 1500 S ------------------------------------------------------------------------------------------------------------------------------------ 60 N206-POS1 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 70 N206-POS1 WFPC2 IMAGE PC1-FIX F502N 1 1500 S ------------------------------------------------------------------------------------------------------------------------------------ 80 N206-POS1 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 220D TO 230D 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 N206-POS2 WFPC2 IMAGE PC1-FIX F656N 1 1600 S ------------------------------------------------------------------------------------------------------------------------------------ 20 N206-POS2 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 8] Visit: 04 Visit Priority: Visit Requirements: ORIENT 265D TO 275D 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 N63A WFPC2 IMAGE PC1-FIX F502N 1 1600 S ------------------------------------------------------------------------------------------------------------------------------------ 20 N63A WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 8110( 5) - 10/24/00 17:39 - [ 9] Summary Form for Proposal 8110 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF3-FIX PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 220D TO 230D ORIENT 40D TO 50D ORIENT 265D TO 275D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N F673N F502N ------------------------------------------------------------------------------------------------------------------------------------ Target Names N49 N206-POS1 N206-POS2 N63A ------------------------------------------------------------------------------------------------------------------------------------