Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3600c Report Date: 09-May-96:18:44 Version: ********** Check-in Date: ********** 1.Proposal Title: OSCILLATIONS, FLARES, AND TOMOGRAPHY OF AE AQUARII ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO Sub Category ERUPTIVE BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Keith Horne STSCI USA 301-338-4964 ------------------------------------------------------------------------------------ 7. Abstract AE Aquarii is the most rapidly spinning of the magnetic cataclysmic variables. Its 16.5 and 33s oscillations and large aperiodic flaring have been studied at radio, optical, x-ray, and TeV gamma-ray energies but never before in the UV. Accretion onto the magnetic poles of the white dwarf is thought to produce rotating x-ray searchlight beams that irradiate the surrounding accretion flow. The impressive flares may represent accretion rate fluctuations gated by magnetic reconnection near the co-rotation radius, where disk material enters the magnetosphere. The source of relativistic electrons producing the highly variable spectrum of unpolarized radio emission is uncertain. We propose FOS,G160L observations in RAPID (1s) readout mode for 7 consecutive HST orbits covering one 9.88h binary period to measure the oscillations and flares as a function of wavelength and binary phase, and to investigate relationships between the oscillations and flares. We predict 1-20 percent oscillations in the UV, making this the only spectral region in which the oscillations can be studied with good S/N. HST has sufficient sensitivity and time resolution to make this an easy experiment. Besides clarifying the nature of the oscillations and flares, we will perform doppler and time-delay tomography of the UV emission-line regions in the system. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3600c PI: Keith Horne Proposal Title: OSCILLATIONS, FLARES, AND TOMOGRAPHY OF AE AQUARII ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Keith Horne STSCI USA Thomas R Marsh OXFORD UNIVERSITY UK X Edward L Robinson UNIVERSITY OF TEXAS AT AUSTIN USA Janet H Wood UNIVERSITY OF TEXAS AT AUSTIN USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will use the FOS with Blue digicon and G160L grating in RAPID readout mode to obtain a time resolution of 1s covering with 6.5A/pixel the spectral region 1150- 2300 Angstroms. The order 0 spectrum also available in this mode will provide a simultaneous record of optical variations along with the UV spectral variations. A short sequence with FOS/BLUE PRISM will also be obtained to see if MgII oscillates or flares. We need to observe AE Aqr for one complete 9.88 hour binary orbit period in order to determine the pulse-timing orbit of the UV oscillations, and to perform the tomographic mapping of the emission-line regions. This will require 7 HST orbits. A total on-target exposure time of 5 hours will be accumulated given that the earth will occult AE Aqr roughly half the time, permitting 35-45m observing per HST orbit. Because the spectral resolution is quite low (600 km/s/pixel) compared to the line widths (3000 km/s), the gaps in phase coverage will not greatly hamper the doppler tomography experiment. The 35- 45 minute continuous observing window in each HST orbit is long enough to give a fair sample of the the oscillation and flaring behavior at that binary phase; the flares last typically 10 minutes. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is needed to provide UV sensitivity and time resolution sufficient to detect the 33 and 16.5s oscillations, and the flares. IUE has been used to define the time-averaged spectrum of AE Aqr (see figure), but it is useless for the high time-resolution observartions we need here. Ground-based studies have been important in establishing the basic nature of the AE Aqr system, the existence of flares and oscillations, the binary orbit and white dwarf spin period, and have raised the questions that are being addressed in this HST experiment. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We need observations on 7 consecutive HST orbits to cover the full 9.88 hour binary orbit period. We considered a series of shorter exposures with time- critical requirements designed to hit specific binary phases, but the overheads involved with target acquisition makes that approach far less efficient than acquiring AE Aqr once and observing for 7 consecutive HST orbits. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The spectra will be reduced using the standard pipeline software using workstations at STScI. The co-investigators will take copies of the reduced data to their home institutions for analysis. We will display the data as trailed spectrograms, as power spectra vs wavelength, and as power spectra vs time. We will decompose the spectra into mean, rms, and oscillation components, and fit models to each of these. We have already developed software for doppler tomography and echo mapping, and will be modifying the echo-mapping code to exploit rotation of the binary system to construct 2-d maps. Photoionization codes will be run for comparison of the mean and variable components of the emission-line spectra. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We will attempt to obtain simultaneous coverage with ground-based telescopes, but this should not affect the success of the HST observations, which form a self -contained experiment. ------------------------------------------------------------------------------------ 9. Description of previous HST work. GO-2380 "Instabilities in Accretion Disks and the Outbursts of Dwarf Novae" Horne and Marsh - data under analysis. GO-2334 "Ultraviolet Spectroscopy of the Black Hole A0620-00" McClintock, Remillard, and Horne - data under analysis. GO- 3232 "Observations of X-Ray Nova Muscae 1991" Panagia, Lund, Gilmozzi, Horne, Paresce, Valle, and Schrader. - paper submitted to Ap.J. (None of these is closely related to this proposal.) ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Salary and basic computer facilities are being provided for the P.I. ------------------------------------------------------------------------------------ 11. Address Information Name: KEITH HORNE Category: PI Institution: STSCI Address: 3700 SAN MARTIN DRIVE City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: 410-338-4964 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3600c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 AE-AQR A,151,154,161 PLATE-ID = 02C4, J2000 1 V = 10.8 +/- 1.1 RA = 20H 40M 9.02S +/- 0.5", 1 B-V = 0.8 DEC = -0D 52' 15.5" +/- 0.5" 2 F-CONT(1500) = 3 +/- 1 E-13 Comments: VARIABLE STAR, UV MAY VARY BY 1MAG IN 10MIN. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3600c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE AE-AQR FOS/BL ACQ/ 4.3 G160L 1 10S 1 1 ONBOARD ACQ FOR AEAQR PEAK 1.5 GROUP 1-3 NO GAP SPATIAL SCAN Comments: BRIGHT VARIABLE STAR. UV MAY VARY BY 1MAG IN 10MIN. 0.26S GIVES 300 X 11 COUNTS. ------------------------------------------------------------------------------------------------------------------------------------ 1.5 DEFINE AE-AQR FOS/BL ACQ/ 1.0 G160L 1 10S 1 1 ONBOARD ACQ FOR 2- AEAQR PEAK 3 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE AE-AQR FOS/BL RAPID 4.3 G160L READ-TIME=3.2 1 20M 1 AEAQR SUB-STEP=2 Comments: 9.88 HR BINARY PERIOD TAKES 7 OR MORE CONSECUTIVE HST ORBITS. 5H EXPOSURE ASSUMES 45M PER HST ORBIT. 4S READOUTS FOR FLARES, AND 16.5S OSCILLATIONS. ------------------------------------------------------------------------------------------------------------------------------------ 2.5 DEFINE AE-AQR FOS/BL RAPID 4.3 G160L READ-TIME=3.2 7 40M 1 AEAQR SUB-STEP=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE AE-AQR FOS/BL RAPID 4.3 PRISM READ-TIME=3.2 1 40M 1 AEAQR SUB-STEP=2 Comments: RAPID READOUT REQUIRED FOR FLARES, AND 16.5 AND 33 SEC OSCILLATIONS. ------------------------------------------------------------------------------------------------------------------------------------ 4 USE CYCLE 2 / 1-4 AEAQR AT 30-AUG-1992 +/- 70D Comments: RELAX TIMING CONSTRAINT IF REQUIRED FOR SCHEDULING. PI HAS COORDINATED OBSERVATIONS PLANNED. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 3600c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 1 FGS Scan: DWELL Dwell Only: dwell points/line: 3 Seconds per dwell: 1.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 2.8000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 0.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.4000 Width Offset (arc-sec): 0.0 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 1.5 FGS Scan: DWELL Dwell Only: dwell points/line: 6 Seconds per dwell: 1.00 Scan width (arc-secs): 0.7000 Scan length (arc-secs): 3.5000 Angle between sides (degrees) 90.00 Number of lines: 2 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.7500 Width Offset (arc-sec): 0.3500 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3600c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters READ-TIME=3.2 SUB-STEP=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 1.5; GROUP 1-3 NO GAP; SPATIAL SCAN; ONBOARD ACQ FOR 2-3; CYCLE 2 / 1-4 ; AT 30-AUG-1992 +/- 70D ; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160L PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names AE-AQR ------------------------------------------------------------------------------------------------------------------------------------