Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5418 Report Date: 18-Jul-95:17:21 Version: ********** Check-in Date: ********** 1.Proposal Title: THE ORIGIN OF THE ULTRA-VIOLET SPECTRAL COMPONENTS IN THE POLAR-LIKE INTERMEDIATE POLAR, RE075 CYCLE 4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Sub Category ERUPTIVE BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Simon R Rosen UNIVERSITY OF LEICESTER U.K. ------------------------------------------------------------------------------------ 7. Abstract RE0751+14, is arguably the most important magnetic cataclysmic variable (CV) to be discovered for many years. Although it is undoubtedly an intermediate polar, it also exhibits highly unusual properties (e.g. a strong EUV component, modulated optical/IR polarization, X-ray, optical and IR dips in its rotational light curve and a very red rotational pulsation) which strongly suggest that its white dwarf possesses a powerful magnetic field, similar to that associated with the strongly magnetic (B>10MG) polars. Thus RE0751+14 is apparently an interloper, occupying a new, uncharted domain in the field distribution of the magnetic CVs which was previously thought to be bimodal. The study of RE0751+14 is therefore of fundamental importance to our knowledge of the field distribution in magnetic CVs and consequently of their evolutionary relationship. The UV waveband is crucial to this study because magnetic disruption and control of the accretion flow occurs at radii where the hot UV emitting material exists. We are proposing to use the HST FOS to secure the first highly time-resolved UV spectroscopy of RE0751+14. These will enable us, for the first time, to a) segregate the different UV continuum components (via their different temporal behaviour) and characterize their sources and b) measure the emission line flux variations to probe physical structure within the system. These observations will be complemented by a parallel HRS proposal to study the CIV line in detail. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 8.50 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5418 PI: Simon R Rosen Proposal Title: THE ORIGIN OF THE ULTRA-VIOLET SPECTRAL COMPONENTS IN THE POLAR-LIKE INTERMEDIATE POLAR, RE075 CYCLE 4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Simon R Rosen UNIVERSITY OF LEICESTER UNITED KING X Domitilla De Martino 7650 SPAIN X Martine Mouchet 5414 FRANCE X Keith Mason 8054 UK X Mike Watson 8042 UK X Andrew King 8042 UK X Steve Howell 3180 USA Coel Hellier 3550 USA Trevor Ponman DEPT OF SPACE RESEARCH, UK X UNIVERSITY OF BIRMINGHAM Jean-Marc Bonnet-Bidaud 5414 FRANCE X Jon Mittaz 8054 UK X Pasi Hakala 5330 FINLAND ------------------------------------------------------------------------------------ 3. Description of proposed observations. We are proposing to secure highly time-resolved FOS UV spectra of the polar-like intermediate polar, RE0751+14. Before we can fully assess exactly why this new object is so different from other IPs and how it fits into the evolutionary and structural framework of the magnetic CVs, we must identify and establish the nature of the various sources of emission in the system. Separating the different components (emission sources) such as the magnetically dominated accretion flow, any disk and perhaps a disk bright spot, is facilitated by the fact that they will vary on different timescales (i.e. the white dwarf rotation period, the orbital period and the beat period between them). We aim to identify spectral variability on these different timescales to isolate and quantitatively characterize the sources of continuum emission in the UV which probes the vitally important inner regions on and around the white dwarf. These observations, together with a parallel HRS proposal to study the C IV line in detail, will provide essential information about the relationship between the line and continuum sources. To achieve these objectives we will use the FOS with the 0.9" aperture and the G160L grating to cover the 1150-2500A wavelength range. Use of the blue digicon detector is preferred so as to provide coverage down to the shortest UV wavelengths (essential to monitor the putative steep component in the far UV). We request coverage of one binary orbital period (6 hrs). Observations should be carried out using FOS RAPID mode, acquiring continuous sequences of 10s exposures. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Testing for the presence of the UV emitting inner disk, constraining the tail of the emission from the heated accretion region and identifying the source of the beat period variations in RE0751+14 are all issues that can only (or are best) resolved by spectral studies in the UV, hence the need for space-borne instrumentation. We recently (Feb 1993) secured an IUE observation of RE0751+14 which, when combined with our optical and IR spectra, shows a distinct flattening at UV wavelengths. Moreover, these spectra show evidence for continuum and line variations on timescales comparable to the 5.3 hr orbital period. However, we also expect spectral variability to occur on the 13.9 minute white dwarf rotation period in RE0751+14 which means we must subsample this timescale. The relative faintness of RE0751+14 (V~14.5) demands lengthy exposure times (multiples of the 13.9 minute spin cycle) with IUE to achieve adequate spectral quality. In any case, the readout and preparation times (~30 mins) inherent with the IUE cameras severely limit the rapidity with which exposures could be taken. To achieve our objectives, we must sample the UV spectrum on timescales at least as short as 1 minute and this can only be done with HST. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We are not requesting time-critical observations. However, it is particularly worth noting that the binary orbital period of ~5.3 hours in RE0751+14 is very well suited to the use of contiguous HST orbits. The requested exposure of 6 hours, assuming we get about 40 mins of data per HST orbit, requires about 9 orbits (each 40 minute window covers about 0.13 orbital cycles). Fortuitously, it turns out that (because the 96 minute HST orbit is almost exactly 0.3 of a binary cycle) if these orbits are scheduled contiguously, the phase sampling is near perfect and is extremely efficient, leaving essentially no gaps in the orbital coverage. We will also cover more than 2 spin cycles in each HST orbital window (ie >20 spin cycles in total). ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Routine FOS calibration data will be sufficient for our purposes. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. To maximize compatibility between our HST spectra and the optical distribution, we will be aiming to secure simultaneous or near simultaneous ground-based optical data. Long timescale (weeks-years) changes in the system could invalidate simple combining of our current optical spectra with the HST UV data. If we can establish that such changes have not occurred (e.g. if the optical spectra taken simultaneously with the HST are similar to those we already possess), we can then incorporate data from a wider wavelength range (X-ray/EUV and IR) to provide broader spectral coverage for the model fits. We point out, however, that whilst these contemporaneous optical observations are desirable and their arrangement will be vigorously pursued, the proposed UV study is a stand-alone project which will provide vital new information on the nature of RE0751+14, irrespective of whether other data are secured at the same time. We stress that we will be seeking to arrange suitable optical observations that fit in with the HST schedule, rather than requiring HST observations to be dependent on optical scheduling. Nevertheless, the optimum ground based observing time is between November and early March and HST observations in, or as near to this interval as possible, will allow maximum continuous ground-based coverage. Obtaining the necessary optical observing time should not be a problem as one of the collaborators, SBH, has access to the Lowell observatory whilst another, CH, has access to the McDonald observatory. In both cases, observing allocations can be gained at relatively short notice. To extend the coverage, we will also apply for observing time on the RGO (SRR,KOM) or Nordic optical telescope on La Palma (PJH) and also at the Canada-France-Hawaii and 6m Zelenchuk (MM,JMB-B) telescopes. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. GO-3578 Line eclipse mapping of an accretion disk wind. (KOM). GO-3579 The UV orbital lightcurve of the X-ray binary X1822-371. (KOM). GO-4661 Ultra- violet eclipse mapping of the accretion flow in the eclipsing Intermediate Polar, EX Hya. (SRR,KOM,MGW). GO-4449 Occultation studies of RE1149+28: An object with an extreme EUV/optical ratio. (JPDM,KOM,SRR). None of these proposals/observations are related to the objectives being pursued here. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The analysis of our HST data will be undertaken by the PI and the Co-I's. All proposers have access to DEC Vax and alpha machines or SUN stations which are dedicated to astronomical research. ------------------------------------------------------------------------------------ 11. Address Information Name: SIMON R ROSEN Category: PI Institution: University of Leicester Address: Dept. of Physics, University Rd., City: Leicester State: Zip Code: Country: UNITED KINGDOM Telephone: 0533 552077 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5418 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 STAR- A, 154 RA = 07H 51M 17.39S +/- J2000 1 V = 14.5 +/- 0.1 075117+14442 0.03S, 2 B-V = 0.1 +/- 0.2 4 DEC = +14D 44' 24.6" +/- 3 E(B-V) = 0.0 +/- 0.1 0.4", 4 F-CONT(1200) = 3.0 +/- 0.7 E-14 PLATE-ID = 01LS 5 F-CONT(1550) = 2.8 +/- 0.7 E-14 6 F-LINE(1550) = 2.0 +/- 1.5 E-13 7 W-LINE(1550) = 10 +/- 3 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5418 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 STAR- FOS/BL ACQ/ 4.3 G400H SCAN-STEP- 1 0.2S 1 1 ONBOARD ACQ FOR 075117+1444 PEAK Y=1.204 3 1.5 24 SEARCH-SIZE-X=1 CYCLE 4 SEARCH-SIZE-Y=3 Comments: CONTIGUOUS ORBITS FOR LINES 1- 10 ARE HIGHLY DESIRABLE TO GET MOST UNIFORM COVERAGE OF 5.5H ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 1.5 STAR- FOS/BL ACQ/ 1.0 G400H SCAN-STEP- 1 0.2S 1 1 ONBOARD ACQ FOR 075117+1444 PEAK X=0.602 3 1.7 24 SCAN-STEP- CYCLE 4 Y=0.602 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 1.7 STAR- FOS/BL ACQ/ 0.3 G400H SCAN-STEP- 1 1S 1 1 ONBOARD ACQ FOR 2- 075117+1444 PEAK X=.172 3 10 24 SCAN-STEP- CYCLE 4 Y=.172 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 2 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 Comments: THIS IS A 13.9 MIN PULSAR SO DATA SEGMENTS SHORTER THAN THIS ARE OF LIMITED USE. DATA WILL BE PHASE FOLDED FOR S/N. IF 40 MIN EXPOS- URES ARE NOT FEASIBLE, MORE, SHORTER EXPOSURES CAN BE USED. ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 4 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 5 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 6 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5418 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 7 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 8 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 9 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 40M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ 10 STAR- FOS/BL RAPID 1.0 G160L 1850 COMB=YES 1 20M 5 5 1 CYCLE 4 075117+1444 READ-TIME=10 10S 24 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5418 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.204 SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-X=0.602 SCAN-STEP-Y=0.602 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=.172 SCAN-STEP-Y=.172 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 COMB=YES READ-TIME=10 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 8.50 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 1.5; CYCLE 4; ONBOARD ACQ FOR 1.7; ONBOARD ACQ FOR 2-10; CYCLE 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G400H G160L ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-075117+144424 ------------------------------------------------------------------------------------------------------------------------------------