7383( 4) - 01/26/99 09:53 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7383 Version: 4 Check-in Date: 26-Jan-1999 09:52:35 1.Proposal Title: High resolution imaging of magnetically-propelled ejecta from the cataclysmic variable AE Aqr ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Martin Still University of St. Andrews CoI: Keith Horne University of St. Andrews N CoI: Graham Wynn University of Leicester N CoI: Rob Fender University of Sussex N ------------------------------------------------------------------------------------ 5. Abstract We propose PC imaging of the field about the cataclysmic variable AE Aqr. The recent suggestion that accreting material in CVs is diamagnetic and non-homogeneous provides a spectacular prediction for the fate of accreting gas in the circumstellar environment of AE Aqr - namely that the accretion stream unavoidably gains energy and angular momentum via interaction with the magnetosphere of the rapidly rotating white dwarf. The net result of this magnetic propeller is that 99% of the accreting material is ejected from the system, forming an equatorial spiral nebula. PC imaging is the only direct experiment available to test this prediction. If found, not only will the long-standing problems concerning the nature of AE Aqr be solved, but the nebula will provide proof that diamagnetic interaction can drive mass and angular momentum, and must be considered in order to provide a physical treatment of accretion in magnetic media. In many cases the addition of this element to accretion models provides major deviations from previously predicted gas behaviours and is able to explain a diverse number of observed phenomena in CVs which have remained unsolved until now. ------------------------------------------------------------------------------------ 7383( 4) - 01/26/99 09:53 - [ 2] Observations Description ------------------------ We will take PC images of the circumstellar environment about the cataclysmic variable AE Aqr through the HAlpha filter (F656N) and the wide filter (F675W) in order to subtract the central source from the HAlpha exposures. The V magnitude of AE Aqr peaks at 10.4 during short flare states, hence exposure times are limited by the stellar brightness. em Integrations will be 60 s for F656N exposures and 0.8 s for F675W exposures. This will saturate the chip at the centre of the psf of the star, but will avoid blooming during readout, thus maximizing signal in the wings of the point source without incurring pixel leakage. S/N was calculated using the WFPC2 Exposure Time Calculator Tool. Total counts from the point source through F656N are 4 * 10^5 electrons per 60 s exposure. The background is dominated by the psf of the point source. Figure 5.1 of the WFPC2 manual provides an estimate of 4 * 10^3 electrons per pixel at 0.1 arcsec from the source, contributing a shot noise of N1 = 63 electrons. Subtraction of the psf provides noise of the same order, N2. The experiment is to subtract the central source psf and look for extended wing structure. The HAlpha surface brightness of the nebula is: L(HAlpha) ~ 3 * 10^-13 erg/cm^2/s^1/arcsec^2 at 0.1 arcsec from the source. The total HAlpha count from the nebula from a 60 s exposure, 0.1 arcsec from the source, is S = 260 electrons/pixel. Dark counts and the sky background are negligible. Readout noise N3 = 5.2 electrons. From these numbers we predict a S/N, given by S / N1^2 + N2^2 + N3^2 + S, of ~ 3 from each integration. 4 orbits of HST will provide us with 26 individual exposures of the target through F656N and 25 through F675W. This gives an accumulated S/N of (26 * 3)^0.5 = 15 for the target nebula at a distance of 0.1 arcssec from AE Aqr. Real Time Justification ----------------------- None. Calibration Justification ------------------------- None. Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7383( 4) - 01/26/99 09:53 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AE-AQR STAR, Intermediate RA=20H 40M 9.07S +/- 0.4", DEC=- J2000 V = -63 V = 10.4+/-0.5 Polar, Interacting 00D 52' 16.3" +/- 0.4", PLATE- F-LINE(6562)=1.4e-13 Binary ID=02C4 W-LINE(6562)=20 Comments: The aim of the experiment is to detect the background line flux which extends to 5-6 pixels around the bright central source. This can only be achieved if the line flux coming directly from the central source saturates the pixels at the centre of the point spread function without introducing blooming. The fluxes given are for the central source. The central source flares violently and may be as bright as R=10. There is no definite upper limit for the Halpha line flux during flares. The background luminosity is approx. 1% of the point source luminosity in HAlpha. 7383( 4) - 01/26/99 09:53 - [ 4] 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 AE-AQR WFPC2 IMAGE PC1 F675W DITHER-TYPE=BOX 2 0.4 S ------------------------------------------------------------------------------------------------------------------------------------ 9 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 10 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 11 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 12 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 13 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 14 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 15 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 16 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 17 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 18 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 19 AE-AQR WFPC2 IMAGE PC1 F675W DITHER-TYPE=BOX 2 0.4 S ------------------------------------------------------------------------------------------------------------------------------------ 27 AE-AQR WFPC2 IMAGE PC1 F656N 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 28 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 29 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 30 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 31 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 32 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 33 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 34 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 35 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 36 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 37 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 7383( 4) - 01/26/99 09:53 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 38 AE-AQR WFPC2 IMAGE PC1 F675W DITHER-TYPE=BOX 2 0.4 S ------------------------------------------------------------------------------------------------------------------------------------ 46 AE-AQR WFPC2 IMAGE PC1 F656N 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 47 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 48 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 49 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 50 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 51 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 52 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 53 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 54 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 55 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 56 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 57 AE-AQR WFPC2 IMAGE PC1 F675W DITHER-TYPE=BOX 2 0.4 S ------------------------------------------------------------------------------------------------------------------------------------ 65 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 66 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 67 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 68 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 69 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 70 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 71 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 72 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 73 AE-AQR WFPC2 IMAGE PC1 F656N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 74 AE-AQR WFPC2 IMAGE PC1 F656N 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 75 AE-AQR WFPC2 IMAGE PC1 F656N 1 20 S ------------------------------------------------------------------------------------------------------------------------------------ 7383( 4) - 01/26/99 09:53 - [ 6] Summary Form for Proposal 7383 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=BOX ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F675W F656N ------------------------------------------------------------------------------------------------------------------------------------ Target Names AE-AQR ------------------------------------------------------------------------------------------------------------------------------------