7396( 2) - 05/16/97 13:19 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7396 Version: 2 Check-in Date: 16-May-1997 11:06:44 1.Proposal Title: UV Cyclotron Spectroscopy of the High- Field Polar UZ Fornacis ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle BINARY STARS GO 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: THIERRY ROUSSEAU UNIVERSITAETS-STERNWARTE GOETTINGEN CoI: Andreas Fischer Universitaets-Sternwarte Goettingen N CoI: Boris Gaensicke Universitaets-Sternwarte Goettingen Y CoI: Klaus Reinsch Universitaets-Sternwarte Goettingen N CoI: Klaus Beuermann Universitaets-Sternwarte Goettingen N ------------------------------------------------------------------------------------ 6. Abstract UZ Fornacis is a high-field polar with 53 MG at the main accreting pole and 75 or 113 MG at the second pole. The system displays pronounced optical cyclotron line emission which increases in intensity towards the UV. UZ for ist ideally suited to derive the distribution of mass flow rates in the accretion spot on the white dwarfs in polars by a new method developed by us on the basis of our radiation-hydrodynamic calculations. We propose to take three spectra each with the STIS at the two orbital phases when the main accreting pole is in or out of view, respectively. This will allow us to determine (i) the area of the accretion spot, (ii) the distribution of the mass flow rates in the spot over a wide range from 10^-3 to ~ 10 g,cm^-2s^-1, (iii) the temperature of the accreting white dwarf, and (iv) the field strength at the secondary high-field pole of UZ For (75 or 113 MG). This information allows for the first time to model the internal structure of the accretion spot. ------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 2] Observations Description ------------------------ noindent 1 Instrumentation, UZ Fornacis shall be observed with the STIS using the gratings G140L, G230L, and G430L, with the slit 52 * 0.5. This will cover the regions 1150 to 1736 Angstrom, 1570 to 3180 Angstrom, and 2900 to 5700 Angstrom with R ~ 500 - 1000. G430L data will be taken with the CCD in the ACCUM mode. G230L and G140L data will be taken with the NUV/FUV MAMA's in the TIMETAG mode. We will need altogether four HST orbits. The expected overhead times per orbit are: 9 min for guide star acquisition, 8 min for target acquisition, and ~ 6 - 8 min of instrumental setup/wavelength calibration. Considering the visibility of 53 min of UZ For, this leaves ~ 28 min (= 1680 sec) exposure time per orbit. If all visits are scheduled within 2 - 4 weeks, only the first visit requires a target acquisition (see STIS Manual, p. 124) and, hence, the following visits will contain additional ~ 8 min exposure time. Both, faint and bright phase will be observed with all three gratings. Based on the known low-state faint-phase spectrum, the worst-case S/N to expect are 5, 8, 15 for the gratings G140L, G230L, G430L, respectively. In a high state, the S/N ratios increase to 10, 15, 25. As the cyclotron emission causes broad emission features, rebinning the date will enhance the S/N. Scheduling: All four visits will be scheduled according to the ephemeris: HJD(Phi = 0.00) = 2445567.17627 + 0.0878654371 (Warren et al. 1995). visit 1: G430L, exposure centered on Phi ~ 0.35 (faint phase). visit 2: G430L, exposure centered on Phi ~ 0.85 (bright phase). visit 3: G140L, exposure centered on Phi ~ 0.35 (faint phase). visit 4: G230L, exposure centered on Phi ~ 0.85 (bright phase). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 UZ-FOR STAR,POLAR,INTERACTING RA=03H 35M 28.6S +/- 0S,DEC=-25D J2000 V = 19.0+/-1.5 BINARY 44' 22.5" +/- 0",PLATE-ID=027X B-V = 1.0+/-0.2 E(B-V) = 0.05+/-0.05 F(1400)=1.0+/-0.5e-14 7396( 2) - 05/16/97 13:19 - [ 4] Visit: 01 Visit Requirements: PERIOD 0.0878654371 D AND ZERO-PHASE JD2445567.17627 GROUP 1-4 WITHIN 14D On Hold Comments: Additional Comments: bright phase Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 UZ-FOR STIS/C ACQ F28X50L MIRROR 1 10 S PHASE 0.53 TO 0.58 CD P ONBOARD ACQ FOR 2 SEQ 1-2 NON-INT SAVE OFFSET UZFOR1 ------------------------------------------------------------------------------------------------------------------------------------ 2 UZ-FOR STIS/C ACCUM 52X0.5 G430L 4300 CR-SPLIT=4 1 1760 S SEQ 1-2 NON-INT CD ------------------------------------------------------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 5] Visit: 02 Visit Requirements: PERIOD 0.0878654371 D AND ZERO-PHASE JD2445567.17627 GROUP 1-4 WITHIN 14D On Hold Comments: Additional Comments: faint phase Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 UZ-FOR STIS/C ACCUM 52X0.5 G430L 4300 CR-SPLIT=2 1 800 S PHASE 0.1 TO 0.2 USE CD OFFSET UZFOR1 SEQ 3-4 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 4 UZ-FOR STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=1000 1 800 S USE OFFSET UZFOR1 SEQ 3-4 UV-MAM G NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 6] Visit: 03 Visit Requirements: PERIOD 0.0878654371 D AND ZERO-PHASE JD2445567.17627 GROUP 1-4 WITHIN 14D On Hold Comments: Additional Comments: faint phase Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 5 UZ-FOR STIS/F TIME-TA 52X0.5 G140L 1425 BUFFER-TIME=1000 1 1860 S USE OFFSET UZFOR1 PHASE UV-MAM G 0.1 TO 0.2 NO SPLIT A ------------------------------------------------------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 7] Visit: 04 Visit Requirements: PERIOD 0.0878654371 D AND ZERO-PHASE JD2445567.17627 GROUP 1-4 WITHIN 14D On Hold Comments: Additional Comments: bright phase Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 UZ-FOR STIS/F TIME-TA 52X0.5 G140L 1425 BUFFER-TIME=1000 1 660 S PHASE 0.55 TO 0.6 USE UV-MAM G OFFSET UZFOR1 SEQ 6-7 A NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 7 UZ-FOR STIS/N TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=1000 1 660 S USE OFFSET UZFOR1 SEQ 6-7 UV-MAM G NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 7396( 2) - 05/16/97 13:19 - [ 8] Summary Form for Proposal 7396 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=4 CR-SPLIT=2 BUFFER-TIME=1000 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category BINARY STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 0.0878654371 D AND ZERO-PHASE JD2445567.17627 GROUP 1-4 WITHIN 14D PHASE 0.53 TO 0.58 ONBOARD ACQ FOR 2 SEQ 1-2 NON-INT SAVE OFFSET UZFOR1 SEQ 1-2 NON-INT PHASE 0.1 TO 0.2 USE OFFSET UZFOR1 SEQ 3-4 NON-INT USE OFFSET UZFOR1 PHASE 0.1 TO 0.2 NO SPLIT PHASE 0.55 TO 0.6 USE OFFSET UZFOR1 SEQ 6-7 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L G230L G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names UZ-FOR ------------------------------------------------------------------------------------------------------------------------------------