6770( 5) - 04/01/97 13:51 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6770 Version: 5 Check-in Date: 01-Apr-1997 13:44:52 1.Proposal Title: Resolving the nature of nova shells ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle INTERSTELLAR MEDIUM GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: TIMOTHY J. O'BRIEN LIVERPOOL JOHN MOORES UNIVERSITY CoI: Dr. Huw Lloyd Liverpool John Moores University N CoI: Andrew Slavin Liverpool John Moores University N CoI: Prof. Mike Bode Liverpool John Moores University N ------------------------------------------------------------------------------------ 6. Abstract We propose to conduct WFC observations of the nebular remnants of 11 novae. We have already demonstrated the usefulness of these observations with a deep, predominantly H alpha, imaging survey of 37 classical nova remnants using the William Herschel and Anglo-Australian Telescopes. This has resulted in the detection of new nebular remnants and the resolution of detailed structure in previously known remnants. The data indicate a strong correlation between nova speed class and the ellipticity of the resulting remnants - those of faster novae tend to comprise randomly distributed clumps of ejecta superposed on spherically-symmetric diffuse material, whilst slower novae produce more structured ellipsoidal remnants with at least one and sometimes several rings of enhanced emission. High-resolution optical images of these faint, and often rather small (several arcseconds) structures will enable us to classify them, thereby placing nova shell research on a similar footing to studies of the shaping of planetary nebulae. The results will have implications for the dynamics of common-envelopes, hydrodynamic instabilities and dust formation in novae, the calibration of the distance scale and the determination of ejecta masses. ------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 2] Observations Description ------------------------ Our sample comprises 11 novae selected from those which we have recently observed using the WHT and AAT. The selection criteria are as follows: (i) The objects have not been previously observed or scheduled to be observed with the HST (excepting HR Del for which there is a pre-COSTAR saturated image in the data archive); (ii) A shell was detected in our ground-based survey; (iii) The objects cover a range of speed classes; (iv) The WFPC2 will provide an image of comparable quality (in terms of resolution) with our ground-based images of DQ Her. The exposure times for these observations have been calculated using our own ground-based images and the observed V magnitudes and colours of the central stars (from: Bruch & Engel 1994, A&A Supp. 104, 79; Szkody 1994, AJ, 108, 639; Warner 1986, MNRAS, 222, 11; AAVSO lists). We have compared the performance of the HST/WFC with the WHT in order to assess the relative quality of the ground-based and proposed HST images. Allowing for the differences in system throughput (effective areas, filter efficiency, instrument throughput, detector efficiency) we find that the WHT is 5* more efficient than the HST/WFC. For point sources, allowing for the difference in pixel scale and FWHM of the PSF, we find that the WHT is about 1.8* more efficient than the HST/WFC and about 2-3* more efficient than the HST/PC. This implies that if the emission from the shell of FH Ser were entirely contributed by point sources then a WFC image at the same signal to noise as our ground-based data but with 20* better resolution (assuming a dither) could be obtained with an HST exposure of about 500 seconds. However, the shell is unlikely to be composed entirely of unresolved point sources, hence this figure can only be considered a lower limit. As we have no way of knowing the actual structure of the shell before these observations are made we have taken total exposure times of one orbit. The larger remnants (RR Pic and T Aur) have been placed on the geometric centre of the WF3 chip. The smaller objects (diameters less than about 10") have been placed on the centre of the PC chip. For the WF3 observations we have specified a default line-type dither in order to improve the spatial resolution. However, because we are not only interested in spatial resolution but also in detecting faint features we have decided not to split each of these exposures in order to identify cosmic rays. Instead we propose to use the two dithered exposures -- we believe that cosmic ray removal by inspecting re- sampled images will be sufficient for our purposes. In the PC1 exposures we have specified a default cosmic-ray split into two sub-exposures. For HR Del, the nebular emission is relatively bright and so to be sure of avoiding saturation of the shell we have specified three separate exposures of this object within the orbit. We are only concerned with the extended faint nebular emission so saturation of the central system in several of these exposures is not avoided. The saturation is not extreme and so blooming will only affect a small region at the centre of the nebular remnants and will not compromise our scientific aims. All the images will use the F656N HAlpha filter. Experience has shown us that these nebular objects are brightest in this line; this will also reduce the relative contribution of the bluer central stars. The bandpass of this filter should enable us to image the whole of the principal ejecta in the majority of our targets. An ADC gain of 7 e/DN was chosen in every case in order to reduce the contribution of readout noise. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 FH-SER STAR,CLASSICAL RA=18H 30M 47.06S +/- 3",DEC=02D J2000 V = 13.5+/-0.5 NOVA,ISM,EJECTA 36' 52.71" +/- 3",PLATE-ID=050S 2 V1500-CYG STAR,CLASSICAL RA=21H 11M 36.56S +/- 3",DEC=48D J2000 V = 16.0+/-1.5 NOVA,ISM,EJECTA 09' 02.73" +/- 3",PLATE-ID=02RW 3 HR-DEL STAR,CLASSICAL RA=20H 42M 20.38S +/- 3",DEC=19D J2000 V = 12.0+/-0.5 NOVA,ISM,EJECTA 09' 39.72" +/- 3",PLATE-ID=02UR 4 RR-PIC STAR,CLASSICAL RA=06H 35M 36.10S +/- 3",DEC=- J2000 V = 12.0+/-0.5 NOVA,ISM,EJECTA 62D 38' 23.7" +/- 3",PLATE- ID=00MS 5 T-AUR STAR,CLASSICAL RA=05H 31M 59.13S +/- 3",DEC=30D J2000 V = 15+/-1.0 NOVA,ISM,EJECTA 26' 44.98" +/- 3",PLATE-ID=00DH 6 V533-HER STAR,CLASSICAL RA=18H 14M 20.51S +/- 3",DEC=41D J2000 V = 14.8+/-0.5 NOVA,ISM,EJECTA 51' 22.27" +/- 3",PLATE-ID=02S0 7 V842-CEN STAR,CLASSICAL RA=14H 35M 52.58S +/- 3",DEC=- J2000 V = 18.0+/-1.0 NOVA,ISM,EJECTA 57D 37' 34.9" +/- 3",PLATE- ID=039T Comments: Central star likely to be brighter than quoted flux which is from quiescence. However exact brightness unknown and in any case saturation does not affect our scientific aims. 8 V476-CYG STAR,CLASSICAL RA=19H 58M 24.50S +/- 3",DEC=53D J2000 V = 15.0+/-1.0 NOVA,ISM,EJECTA 37' 07.61" +/- 3",PLATE-ID=00VQ 9 DK-LAC STAR,CLASSICAL RA=22H 49M 46.93S +/- 3",DEC=53D J2000 V = 14.0+/-1.0 NOVA,ISM,EJECTA 17' 20.46" +/- 3",PLATE-ID=036H 10 DY-PUP STAR,CLASSICAL RA=08H 13M 48.44S +/- 3",DEC=- J2000 V = 16+/-1.0 NOVA,ISM,EJECTA 26D 33' 56.9" +/- 3",PLATE- ID=04NO 11 BT-MON STAR,CLASSICAL RA=06H 43M 47.20S +/- 3",DEC=- J2000 V = 16+/-1.0 NOVA,ISM,EJECTA 02D 01' 14.46" +/- 3",PLATE- ID=02O8 6770( 5) - 04/01/97 13:51 - [ 5] Visit: 01 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 FH-SER WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2400 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 6] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 V1500-CYG WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 7] Visit: 03 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 HR-DEL WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 1600 S ------------------------------------------------------------------------------------------------------------------------------------ 31 HR-DEL WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=NO 1 700 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 8] Visit: 04 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 RR-PIC WFPC2 IMAGE WF3-FIX F656N DITHER-TYPE=LINE,CR-SPLIT=NO 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 9] Visit: 05 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 T-AUR WFPC2 IMAGE WF3-FIX F656N DITHER-TYPE=LINE,CR-SPLIT=NO 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 10] Visit: 06 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 ------------------------------------------------------------------------------------------------------------------------------------ 60 V533-HER WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 11] Visit: 07 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 ------------------------------------------------------------------------------------------------------------------------------------ 70 V842-CEN WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2700 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 12] Visit: 08 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 ------------------------------------------------------------------------------------------------------------------------------------ 80 V476-CYG WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 13] Visit: 09 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 ------------------------------------------------------------------------------------------------------------------------------------ 90 DK-LAC WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2600 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 14] Visit: 10 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 DY-PUP WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2500 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 15] Visit: 11 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 ------------------------------------------------------------------------------------------------------------------------------------ 110 BT-MON WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.5 1 2500 S ------------------------------------------------------------------------------------------------------------------------------------ 6770( 5) - 04/01/97 13:51 - [ 16] Summary Form for Proposal 6770 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-SPLIT=NO DITHER-TYPE=LINE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N ------------------------------------------------------------------------------------------------------------------------------------ Target Names FH-SER V1500-CYG HR-DEL RR-PIC T-AUR V533-HER V842-CEN V476-CYG DK-LAC DY-PUP BT-MON ------------------------------------------------------------------------------------------------------------------------------------