Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1090c Report Date: 09-May-96:16:08 Version: ********** Check-in Date: ********** 1.Proposal Title: PERIODIC VARIATIONS IN DQ HERCULIS STARS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GTO/HSP Sub Category SUBLUMINOUS STARS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Robert C. Bless WISCONSIN, UNIVERSITY OF USA (608) 262-1715 ------------------------------------------------------------------------------------ 7. Abstract The DQ Herculis Stars are cataclysmic variables showing rapid, strictly periodic luminosity variations at either optical or X-ray wavelengths, and usually both. The periods range from 33 sec in AE AQR through 71 sec in DQ Her to 18690 sec in TV Col. The cataclysmic variables are all close binary stars consisting of a late-type star transferring mass to its companion white dwarf star. The white dwarf in the DQ Her stars is magnetized. The periodicities of the DQ Her stars are caused by rotation of the magnetized, acreting white dwarf. We propose to observe the DQ Her stars at ultraviolet wavelengths using the high speed photometer on the space telescope. The purpose of the observations is to investigate the physics of accretion onto compact stars. Revision History: Received on RPS 9/1/89; Added to SCCS 9/5/89 RPSS V7.2 remote & local; Typos corrected; Added data-fmt - SALM 9/7/89 Updated text - SALM 9/28/89; Moved 5 targ to cycle 2 - SALM 2/12/90 Switched 1 targ in cycles 1 & 2 - SALM ------------------------------------------------------------------------------------ 8. Scientific Key Words: CATACLYSMIC VARIABLE STARS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.55 par: 0 10. Num targs pri: 9 par: 0 ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1090c PI: Robert C. Bless Proposal Title: PERIODIC VARIATIONS IN DQ HERCULIS STARS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Richard L. White SPACE TELESCOPE SCIENCE USA INSTITUTE Robert C. Bless WISCONSIN, UNIVERSITY OF USA Joseph F. Dolan NASA, GODDARD SPACE FLIGHT USA CENTER James L. Elliot MASSACHUSETTS INSTITUTE OF USA TECHNOLOGY Edward L. Robinson TEXAS, UNIVERSITY OF USA G. W. Van Citters NATIONAL SCIENCE FOUNDATION USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. The phases and amplitudes of the pulsations of the DQ Her stars usually vary with orbital phase. It is critically important to know how they vary to interpret the pulsations properly. Observations over at least one entire orbit are necessary to define these variations, and, since each star is different, all the stars should be observed. Therefore, we will observe each of the DQ Her stars (except AE Aqr, whose orbital period is exceptionally long) for a length of time equal to one orbital period. The total observing time will be 35 hours. The appropriate filters to use are the continuum filters at 1350 A and 2400 A in the prism pair of filters, and the appropriate integration times are 1/2 second per pair. Cycle 0: 1 Cycle 1: remainder ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The periodic variations exhibited by the DQ Herculis stars in the optical regime may be of a substantially larger amplitude in the ultraviolet region accessible for ST. The funneling of the accretion flows onto the magnetic poles produces regions which are substantially hotter, and thus more luminous, in the ultraviolet than accretion processes in the absence of fields. The ultraviolet photometry may also actually detect the presence of the underlying white dwarf as well. ------------------------------------------------------------------------------------ 13. A program of high speed ultraviolet photometry of the DQ Herculis stars (the intermediate polars) is proposed to search for the ultraviolet counterparts of the rapid, periodic variations previously seen in the optical and X-ray regions. The observations will help to outline the process of viscous accretion in the presence of strong magnetic fields. ------------------------------------------------------------------------------------ 11. Address Information Name: EDWARD L. ROBINSON Category: CON Institution: UNIVERSITY OF TEXAS Address: DEPARTMENT OF ASTRONOMY City: AUSTIN State: TX Zip Code: 78712 Country: USA Telephone: (512) 471-3401 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 = 1090c [ 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 DQ-HER VARIABLE STAR RA = 18H 7M 30.22S +/- .5", 2000 1 V = 16 +/- 1 INTERACTING BINARY DEC = +45D 51' 30.9" +/- .5" Comments: POSREF = ROBINSON ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1090c [ 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 DQ-HER HSP/ ACQ DATA- 1 72S 1 2 ONBOARD UV1 FORMAT=WORD ACQUISITION FOR 2 CYCLE 2 / 1.5-2 ------------------------------------------------------------------------------------------------------------------------------------ 2 DQ-HER HSP/ PRISM 1.0 F248M/ SAMPLE-TIME=0.5 1 4.7H ^ UV1 F135W Comments: FOR LINES 1.5-2, GAPS DUE TO EARTH OCCULTATION SHOULD BE MINIMIZED. PROPOSAL MAY HAVE TO BE MODIFIED DEPENDING UPON STATE OF PRISM MODE CALIBRATION. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1090c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/UV1 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ PRISM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DATA-FORMAT=WORD SAMPLE-TIME=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HSP ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.55 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category SUBLUMINOUS STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQUISITION FOR 2; CYCLE 2 / 1.5-2; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F248M/F135W ------------------------------------------------------------------------------------------------------------------------------------ Target Names DQ-HER ------------------------------------------------------------------------------------------------------------------------------------