Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3238c Report Date: 09-May-96:18:14 Version: ********** Check-in Date: ********** 1.Proposal Title: ECLIPSES OF CATACLYSMIC VARIABLE STARS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GTO/HSP 1092 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Robert C. Bless WISCONSIN, UNIVERSITY OF USA ------------------------------------------------------------------------------------ 7. Abstract The cataclysmic variables are close binary stars consisting of a late-type star and white dwarf. Mass is being transferred from the late-type star to the white dwarf. Unless the white dwarf has an extremely strong magnetic field, the transferred mass forms an accretion disk around the white dwarf. An important reason to observe the cataclysmic variables is that they provide an unparalled way to study nearly all aspects of the accretion of gas onto compact objects. We propose to observe the eclipses of several cataclysmic variables. The eclipse light curves can be used to find information about the geometry and physical conditions in the accretion disk. One star we propose to observe, Z Cha, is a dwarf nova. Eclipse observations of this star will provide information about changes in the structure of the accretion disk over the outburst cycle. Revision History: Prepared for future cycles submission-- BJW 4/22/92; ------------------------------------------------------------------------------------ 8. Scientific Key Words: CATACLYSMIC VARIABLE STARS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.33 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3238c PI: Robert C. Bless Proposal Title: ECLIPSES OF CATACLYSMIC VARIABLE STARS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Edward L. Robinson TEXAS, UNIVERSITY OF USA Robert C. Bless WISCONSIN, UNIVERSITY OF USA G. W. Van Citters NATIONAL SCIENCE FOUNDATION USA Joseph F. Dolan NASA, GODDARD SPACE FLIGHT USA CENTER Richard L. White SPACE TELESCOPE SCIENCE USA INSTITUTE James L. Elliot MASSACHUSETTS INSTITUTE OF USA TECHNOLOGY ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to obtain high speed ultraviolet photometry of the two eclipsing cataclysmic variables Z Cha (orbital P = 1 hr. 47 min.) and V2051 Oph (orbital P = 1 hr. 30 min.). Z Cha is an erupting dwarf nova with outbursts approximately every 60 days; V2051 Oph is a nova-like variable which does not erupt and will serve as a "control". We plan to obtain 20 observations of Z Cha, at approximately 3 day intervals, each observation lasting for two hours. Similarly, we plan to observe V2051 Oph at four times separated by one to three weeks during this same period. Cycle 1 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The eclipses of the white dwarf and surrounding accretion disk by the late type secondary will have the greatest contrast in the ultraviolet where the peak flux is emitted. The functional dependance of disk temperature on radius reveals that observations at 1200 A probe a region of the disk 4 times closer to the white dwarf than observations at 3500 A. Furthermore, accurate eclipse profiles can be obtained from ST, undistorted by transparency changes and scintillation noise, which affect ground based data. ------------------------------------------------------------------------------------ 13. Multicolor ultraviolet photometry of the two eclipsing cataclysmic variables Z Cha (dwarf nova with orbital P = 1 hr. 47 min.) and V2051 Oph (nova-like with orbital P = 1hr. 30 min.) is proposed. A differential analysis of Z Cha in eruption, compared to V2051 Oph, will yield important clues as to the changes in the physical and geometric properties of accretion disks. ------------------------------------------------------------------------------------ 11. Address Information Name: EDWARD L. ROBINSON Category: CON Institution: UNIVERSITY OF TEXAS Address: ASTRONOMY DEPARTMENT City: AUSTIN State: TX Zip Code: 78712 Country: USA Telephone: (512)471-4461 Telex (or e-mail): ------------------------------------------------------------------------------------ Page 3 Name: ROBERT C. BLESS Category: PI Institution: UNIVERSITY OF WISCONSIN Address: WASHBURN OBSERVATORY 475 N. CHARTER STREET City: MADISON State: WI Zip Code: 53706 Country: USA Telephone: (608)262-1715 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3238c [ 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 V2051-OPH A,151 RA = 17H 8M 19.126S +/- .5", 2000 1 V = 15 +/- 2 DEC = -25D 48' 28.873" +/- .5" Comments: POSREF = SIMBAD NOVA-LIKE VARIABLE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3238c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1.5 V2051-OPH HSP/ ACQ DATA- 1 72S 1 2 ONBOARD ACQ FOR 2 UV1 FORMAT=WORD CYCLE 2 / 1.5-2 PCS MODE FINE / 1.5-2 ------------------------------------------------------------------------------------------------------------------------------------ 2 V2051-OPH HSP/ SINGLE 1.0 F145M ^ 45M ^ REPEAT 1.5-2 EVERY UV1 14D +/- 7D FOR 1 MORE TIMES PHASE 0.8 +/- 0.1 PERIOD 0.062427887D +/- Comments: FOR LINE 2, GAPS DUE TO EARTH 0.000000008D OCCULTATION SHOULD BE ZERO-PHASE MINIMIZED. MAX OBS W/IN ONE JD2444043.68012 +/ ORBIT. OF EACH TARGET, UNTIL - 0.00012D THE SYSTEM IS CAPABLE OF RE- USING GUIDE STARS. ORBITAL EPHEMERIS IS HELIOCENTRIC. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3238c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/UV1 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DATA-FORMAT=WORD ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.33 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2; CYCLE 2 / 1.5-2; PCS MODE FINE / 1.5-2; REPEAT 1.5-2 EVERY 14D +/- 7D FOR 1 MORE TIMES; PHASE 0.8 +/- 0.1; PERIOD 0.062427887D +/- 0.000000008D; ZERO-PHASE JD2444043.68012 +/- 0.00012D; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F145M ------------------------------------------------------------------------------------------------------------------------------------ Target Names V2051-OPH ------------------------------------------------------------------------------------------------------------------------------------