8807( 9) - 05/03/00 11:00 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8807 Version: 9 Check-in Date: 03-May-2000 11:00:09 1.Proposal Title: FUV Observations of EX Hya during a Large Multi-wavelength Campaign ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO/DD 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Steve Howell Planetary Science Institute CoI: Knox S. Long STScI Y CoI: Paula Szkody University of Washington N ------------------------------------------------------------------------------------ 5. Abstract EX Hya is an eclipsing binary with an orbital period of 98 minutes and a WD spin period of 67 min, 2/3 of the orbital period in length. EX Hya contains optically thick gas at temperatures of 10, 000 to 100, 000K and thin gas at 1 million Kelvins and higher. temperature plasma. As such, it is a source of strong emission lines throughout the FUV to IR spectral regions. As part of a large 1 million second multi -wavelength campaign, we propose to obtain ultra-violet STIS spectroscopy with the Hubble Space telescope. The UV spectrum of EX Hya is rich in emission lines due to C, Si, AL, N, He and H Lyman alpha. High S/N and time resolution UV spectra of EX Hya will allow determinations of the temperature and density of the UV emitting gas both within the inner disk coronal region and within the accretion funnels. Joining in this campaign are Chandra, RXTE, USA, EUVE, FUSE, and Optical and IR spectroscopy and photometry. ------------------------------------------------------------------------------------ 8807( 9) - 05/03/00 11:00 - [ 2] Observations Description ------------------------ We are conducting a large multiwavelength campaingn to study EX Hya, an eclipsing binary with an orbital period of 98 minutes and a WD spin period of 67 min, 2/3 of the orbital period in length. It is an intermediate polar type of cataclysmic variable in which the white dwarf primary has a magnetic field strength that is strong enough to deviate the local flow of the accretion stream but too weak to completely confine it as in the polars. EX Hya contains an annulus accretion disk whose inner edge becomes interrupted by the magnetic field of the primary star. This disruption of the accretion disk manifests itself as a removal of the inner disk and the production of one or two weakly confined accretion streams extending from the accretion ring onto the white dwarf (WD) surface at its magnetic poles. The slowly rotating white dwarf magnetic field causes the inner disk region to consist of diffuse accretion curtains composed of high temperature plasma. The current stats of approved observations for the campaign is as follows: Satellite/telescope Comments------ --------------------------------------------------------------------- Chandra DD request approved XTE DD request approved XMM Unlikely; still performing IOC USA Pointings each day during the campaign FUSE GO observation to be coordinated HST This request UKIRT Service nights - IR (J, K) time-resolved spectra Apache Point Obs. Two nights (start/end) of optical spectra WHT La Palma One night of high res time-resolved optical spectra JKT La Palma Nights of high speed Blue photometry Braeside Obs. Complete coverage of multi-color photometry AAVSO World-Wide coverage of nightly brightness--------------------- ------------------------------------------------------ The STIS observations that have been approved as part of our DD request are needed to allow a detailed comparison of the FUV spectrum of EX Haya to that at other wavelengths. .UV time-resolved spectra provide an important link between the high energy continuum emission, the continuum+line FUV region and the emission line dominated UV and optical regions. Data covering this entire wavelength range will provide the best input to multi-temperature models of accretion and plasma formation in astrophysics. Howell et al. (1998 AJ 117 1014) showed that the UV emission lines are almost completely driven and produced by the higher energy flux emitted on or near the white dwarf surface. Analysis of the broad component of the UV lines will directly measure the in-falling gas in the accretion funnels onto the white dwarf poles while the narrow components and line wings modulate with mass transfer changes and the white dwarf spin. A search for phase dependent weak absorptions in the UV lines will be made. We will model the temperature and emission measure of the accretion regions throughout the binary rotation (at 0.1 in phase) using thin plasma emission codes, white dwarf models, and multi-component temperature models. Simultaneous X-ray, UV, and optical spectroscopy will provide a map of how the material flows onto the WD, as the measured velocities can be translated into positions from Doppler maps and models for the accretion regions. We will observe EXA Hya using STIS in high time mode with the E140M grating and a 0.2 x0.2 arsec aperture. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- We require that the HST observations occur sometime during the 5 May to 10 June 2000 window. The best case would be to occur simultaneously with Chandra observations. These are not yet scheduled but will be performed during the EUVE window. The six HST orbits are best scientifically if they happen contiguously as this provides sampling of the same WD spin period and binary orbit, eliminating ambiguity from possible variability. ------------------------------------------------------------------------------------ 8807( 9) - 05/03/00 11:00 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8807( 9) - 05/03/00 11:00 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 EX-HYA STAR, INTERMEDIATE RA=12H 52M 24.23S +/- 1", DEC=- J2000 F-CONT(1425)=0.18+/-0.05e-12 POLAR 29D 14' 56.26" +/- 1", PLATE- V = 14.1+/-0.2 ID=02C8 Coordinate Source: GUIDE_STAR_CATALOG 8807( 9) - 05/03/00 11:00 - [ 5] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 05-May-2000 AND 07-Jun-2000 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 EX-HYA STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2200 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2700 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2700 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8807( 9) - 05/03/00 11:00 - [ 6] Visit: 02 Visit Priority: Visit Requirements: AFTER 01 BY 7D TO 12D 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 EX-HYA STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2200 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2700 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 EX-HYA STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=300 1 2700 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8807( 9) - 05/03/00 11:00 - [ 7] Summary Form for Proposal 8807 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BUFFER-TIME=300 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 05-May-2000 AND 07-Jun-2000 AFTER 01 BY 7D TO 12D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names EX-HYA ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------