Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5716 Report Date: 18-Jul-95:17:53 Version: ********** Check-in Date: ********** 1.Proposal Title: SPECTROSCOPIC OBSERVATIONS OF THE EXPOSED WHITE DWARFS IN THE DWARF NOVAE WZ SAGITTAE, U GEMINORUM AND VW HYDRI ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/CAR 1 Long Term yrs 3836 Sub Category ERUPTIVE BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Prof. Edward M. Sion VILLANOVA UNIVERSITY U.S.A. 215 645 7170 ------------------------------------------------------------------------------------ 7. Abstract The central accreting object in compact binaries and other accreting systems is usually hidden from direct observation, enshrouded by optically thick accretion disks which are opaque to the radiation emitted by the central object as it accretes matter. However there are three dwarf novae which clearly reveal their underlying white dwarf accretor in the far UV during dwarf nova quiescence. By probing these degenerate stars before and after their disk accretion events, fundamental insight about the physics of accretion through a disk/boundary layer onto the central object would be attainable. With the HST sensitivity and velocity resolution we will probe the physics of the accretion process in a way never before possible and test/constrain theoretical models of (a) boundary layer heating, depth and mass of heated layers following dwarf nova mass/energy deposition; (b) shear mixing of matter with angular momentum (with conversion of rotational kinetic energy into heat) versus radial accretion; (c) physical processes in the white dwarf envelope (diffusion, convection, mixing and dilution, dredgeup from deeper layers, magnetic channelling etc.) which control/modify the flow of accreted elements. The carbon in WZ Sge may provide the only evidence, independent of often uncertain nova shell abundances, that heavy element dredgeup of core material occurs during the accretion process in cataclysmic variables. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.40 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5716 PI: Prof. Edward M. Sion Proposal Title: SPECTROSCOPIC OBSERVATIONS OF THE EXPOSED WHITE DWARFS IN THE DWARF NOVAE WZ SAGITTAE, U GEMINORUM AND VW HYDRI ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Prof. Edward M. Sion VILLANOVA UNIVERSITY USA Paula Szkody UNIVERSITY OF WASHINGTON USA Ronald L Gilliland ST SCI USA Knox Long ST SCI USA James Pringle ST SCI UK X Keith Horne ST SCI USA Janet Wood UNIVERSITY OF TEXAS, AUSTIN USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. WE WILL OBTAIN THE FIRST HIGH QUALITY UV SPECTRA OF THE EXP- -OSED UNDERLYING WHITE DWARFS IN THREE DWARF NOVAE DURING QUIESCENCE: WZ SGE, U GEM, AND VW HYI, USING THE GHRS AND THE FOS. IN ALL THREE EXPOSED DEGENERATES, OUR MOST CRITICAL OBJECTIVE IS SECURING DETAILED LINE PROFILES, LINE VELOCITIES TO WITHIN 50 KM/S AND THE DETECTION OF WEAK FEATURES. FOR U GEM AND VW HYI WE ALSO SEEK MEASUREMENTS OF THE CONTINUUM VARIATION AT TWO DIFFERENT OBSERVATIONS SEPARATED BY AT LEAST ONE WEEK DURING THE QUIESCENT (INTER- OUTBURST INTERVAL OF VW HYI AND BY AT LEAST TWO MONTHS DURING THE QUIESCENT INTERVAL OF U GEM. IF AVAILABLE SIDE 1 (G140L) OF THE GHRS WOULD BE USED BUT USE OF THE FOS AS INDICATED FOR THE LOW RESOLUTION EXPOSURES DOES NOT COMPROMISE THE SCIENCE. USE OF THE FOS DOES ADD OVERHEAD TIME, RESULTING IN ABOUT A 15% RESOURCE INCREASE FOR THE WHOLE PROGRAM. FOR OUR SPECTRAL LINE DIAGNOSTICS FOR U GEM AND VW HYI: GHRS, G160M, LSA 1369- 1404A, S/N=15/DIODE, = 60/ANGSTROM (COVERING HIGH AND LOW TEMPERATURE ION SPECIES; E.G. O V, SIV). OUR OBSERVATIONS OF WHITE DWARF COOLING IN U GEM AND VW HYI BEFORE AND AFTER ACCRETION EVENTS WILL UTILIZE CONTINUUM TEMPERATURES WITH FOS, G130H, 0.25" SLIT, S/N= 20, COVERING 1150-1600A. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. NO OTHER TELESCOPE IS CAPABLE OF OBSERVING THESE FAINT(V=15) OBJECTS AT HIGH RESOLUTION AND S/N IN THE UV WHEN THEY ARE IN QUIESCENCE. THIS EXPERIMENT WAS IMPOSSIBLE WITH ANY OTHER TELESCOPE AND REQUIRES THE LARGE HST MIRROR AND GHRS AND FOS CAPABILITIES IN ORDER TO EXPLORE THIS NEW FRONTIER OF INVESTIGATION. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. WE NEED TIME CRITICAL OBSERVATIONS FOR U GEM AND VW HYI IN THE SENSE OF OBTAINING SPECTRA OF EACH JUST AFTER THEIR LAST DWARF NOVA OUTBURST AND JUST BEFORE THE NEXT OUTBURST SO AS TO SAMPLE THE WHITE DWARF COOLING OVER THE WIDEST POSSIBLE SPAN OF TIME. FOR U GEM WE NEED A SPECTRUM 1-2 WEEKS AFTER AN OUTBURST AND 1-2 WEEKS BEFORE THE NEXT OUTBURST. THE OUTBURSTS ARE QUITE PREDICTABLE (AAVSO) AND ARE SEPARATED BY ROUGHLY 118 DAYS.THE INTER-OUTBURST TIME OF VW HYI IS ONLY 20 DAYSAND THE OUTBURSTS ARE ALSO QUITE PREDICTABLE (AAVSO). THUS OUR SPECTRA OF VW HYI CAN BE OBTAINED DURING A TWO WEEK INTERVAL BUT AROUND THE OUTBURST. FOR U GEM NOTIFICATION OF TIMING THE OBSERVATIONS WILL BE PROVIDED 90 AND 110 DAYS BEFORE THE TWO VISITS. FOR VW HYI TWO OBSERVATIONS SCHEDULED 20 DAYS APART WILL HAVE ABOUT AN 80% CHANCE OF SATISFYING OUR AIMS. IN THE VERY UNLIKELY EVENT THAT ONE, OR BOTH OF OUR OBSERVATIONS OCCUR DURING OUTBURST, THE DATA WOULD STILL BE OF INTEREST, BUT NOT FOR OUR PRIMARY PROGRAM. THE COUNT RATES AT OUTBURST WOULD NOT BE TOO LARGE FOR THE FOS AND G130H. Original Proposal 3836 was revised to create this program to change GHRS Acq to BRIGHT=RETURN. Lines 0.1-1, 2.1-3, and 4.1-6 were deleleted. Page 3 ------------------------------------------------------------------------------------ 9. Description of previous HST work. NONE YET ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). DEDICATED SPARKSTATION 2 AND IBM MAINFRAME AT VILLANOVA UNIVERITY, WORKSTATIONS AT STSCI, WORKSTATIONS AT THE UNIVERSITY OF WASHINGTON, SUN SPARKSTATION AND MICROVAX AT THE UNIVERSITY OF TEXAS. ------------------------------------------------------------------------------------ 11. Address Information Name: EDWARD M SION Category: PI Institution: VILLANOVA UNIVERSITY Address: DEPARTMENT OF ASTRONOMY AND ASTROPHYSICS City: VILLANOVA State: PA Zip Code: 19085 Country: USA Telephone: 215 645 7702 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5716 [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 3 VW-HYI A,149,161 RA = 04H 09M 11.300S +/- 2000.0 1 V=13.6+/-0.1 0.15S, 1 B-V=+0.0+/-0.1 DEC = -71D 17' 42.00" +/- 3 E(B-V)=0.0+/-0.1 0.15" 4 F-CONT(1400)= 8.0 +/- 1 E-14 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5716 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 2.01 VW-HYI FOS/BL ACQ/ 4.3 G130H SEARCH-SIZE-X=1 1 15S 20 1 ONBOARD ACQ FOR PEAK SEARCH-SIZE-Y=3 25.0S 2.011 SCAN-STEP- CYCLE 4 /2.01-2.02 Y=1.204 Comments: AVOID SCHEDULING DURING SUPERMAX PERIODS JD 2448757, 2448940, 2449164 AVOID 7 DAYS AFTER EACH. ------------------------------------------------------------------------------------------------------------------------------------ 2.011 VW-HYI FOS/BL ACQ/ 1.0 G130H SEARCH-SIZE-X=6 1 20S 10 1 ONBOARD ACQ FOR PEAK SCAN-STEP- 3M 2.012 X=0.602 SEARCH-SIZE-Y=2 SCAN-STEP- Y=0.602 ------------------------------------------------------------------------------------------------------------------------------------ 2.012 VW-HYI FOS/BL ACQ/ 0.3 G130H SEARCH-SIZE-X=5 1 40S 10 1 ONBOARD ACQ FOR PEAK SCAN-STEP- 3M 2.020 X=0.17 SEARCH-SIZE-Y=5 SCAN-STEP- Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ 2.02 VW-HYI FOS/BL ACCUM 1.0 G130H 1 12M 10 1 3M ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5716 [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.204 SEARCH-SIZE-X=6 SCAN-STEP-X=0.602 SEARCH-SIZE-Y=2 SCAN-STEP-Y=0.602 SEARCH-SIZE-X=5 SCAN-STEP-X=0.17 SEARCH-SIZE-Y=5 SCAN-STEP-Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.40 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2.011; CYCLE 4 /2.01-2.02 ONBOARD ACQ FOR 2.012 ONBOARD ACQ FOR 2.020 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names VW-HYI ------------------------------------------------------------------------------------------------------------------------------------