Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4656c Report Date: 09-May-96:19:45 Version: ********** Check-in Date: ********** 1.Proposal Title: SPIN-CYCLE VARIATIONS OF THE UV EMISSION LINES OF INTERMEDIATE POLARS: CYCLE3 MEDIUM ------------------------------------------------------------------------------------ 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 Dr. Coel Hellier DEPARTMENT OF ASTRONOMY, UNI USA 512 471 3000 HUBBLE FELLOW ------------------------------------------------------------------------------------ 7. Abstract The intermediate polars are a prime opportunity for observing the interaction of an accretion flow with a strong magnetic field. Yet many fundamental issues remain unresolved. For instance, it is not known whether the accretion flow passes through a partial accretion disk, as suggested by many optical studies, or whether material accretes through the direct impact of the accretion stream with the magnetosphere, as suggested by the presence of beat period modulations in intermediate polar X-ray light curves. The low energy optical emission might not trace the dominant accretion flow, but we have no velocity information in the X-ray band. Spin-cycle resolved UV spectroscopy will both give velocity information and trace the accretion flow to within 1-2 white dwarf radii of the white dwarf surface, allowing a direct link to the X-ray studies. AO Psc is a typical intermediate polar, is one of the brightest in the UV, and shows the clearest spin-cycle variations in the optical emission lines - it is thus the best target for the first HST spectroscopic study of an intermediate polar. We propose to use the GHRS to obtain high time and spectral resolution observations of the CIV 1550 line, which is prominent in the spectrum of AO Psc. Watching how the line profile changes around the 805-s spin cycle will reveal the accretion flow as it approaches the X-ray emitting shock, settling many uncertainties regarding the flow of material from the magnetosphere onto the white dwarf. ------------------------------------------------------------------------------------ 8. Scientific Key Words: CATACLYSMIC VARIABLES, INTERMEDIATE POLARS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.90 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4656c PI: Dr. Coel Hellier Proposal Title: SPIN-CYCLE VARIATIONS OF THE UV EMISSION LINES OF INTERMEDIATE POLARS: CYCLE3 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Coel Hellier DEPARTMENT OF ASTRONOMY, USA UNIVERSITY OF TEXAS AT AUSTIN Keith O. Mason MULLARD SPACE SCIENCE LABORATORY UNITED KING X Edward L. Robinson DEPARTMENT OF ASTRONOMY, USA UNIVERSITY OF TEXAS AT AUSTIN ------------------------------------------------------------------------------------ 2. Scientific Justification. ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will obtain time-resolved GHRS spectroscopy of the CIV 1550 line of the magnetic cataclysmic variable AO Psc. We will use the G160M grating giving a 34 ang range covering the whole line (FWZI 25 ang). We will use the RAPID mode to obtain a time resolution of 10 secs. This is required to resolve the rapid line profile changes through the 805 sec spin cycle of AO Psc. The requested exposure time is calculated both to give sufficient signal to noise, to cover enough 30 spin cycles to reduce random flickering, and to cover 2 orbital cycles (3.5 hrs). We aim to obtain a signal to noise of about 20 in each of 20 phase bins round the spin cycle with a velocity resolution of 50 Km s-1 in the GHRS spectra (which at 1550 ang corresponds to 4 diodes in the array. The phase-averaged IUE spectrum of AO Psc gives flux levels of 1.4 e-13 and 3.0 e-13 erg s-1 cm-2 A-1 at the base and peak of the CIV 1550 line respectively. Using the quoted sensitivity for our instrumental setup of 4.41 e11, we obtain count rates of 0.06 & 0.13 s-1 diode-1 respectively, or 0.24 & 0.52 counts s-1 per 50 km s-1 resolution element. Hence with our exposure time of 6.9 hrs we will obtain 300 & 650 counts for the base and peak of the line respectively in each resolution element in each spin-phase bin, corresponding to S/N values of 17 & 25. This time cover 30 spin pulses, and thus the data will record genuine spin-cycle variations; observations of a small number of spin cycles can be affected by random flickering in these stars. The time will also cover two 3.5-hr binary periods of AO Psc. This will ensure that after allowing for the effects of earth occultations, SAA etc, the orbital cycle is fully sampled. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The program involves UV spectroscopy of a 13th mag star with a high time resolution (resolving a 13 min period) and a high spectral resolution (< 0.5 ang). The IUE has very long readout times (30 mins) and low sensitivity, which mean that it cannot undertake this project - only low resolution, phase averaged spectra can be obtained. Hence, the program can only by done with the HST. The proposal is to look at high ionization lines (C IV) which are not accessible from the ground. Complementary work on emission lines seen in the optical has been pursued on our target object and several similar systems - this work points to the large gains likely to be made from observing in the UV. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. None required. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None required. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The applicants have substantial experience in similar projects with ground-based optical spectroscopy. Standard reduction procedures will be adequate while the analysis is likely to use similar procedures and software to those developed for the optical studies. To aid interpretation of the results, we also intend further developing our code modelling the geometry of the accretion flow to investigate emission line profiles. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. PI HELLIER has not previously applied for HST time. Co-I MASON has been awarded GO time for 2 projects, neither of which are related to the current proposal. 3578 `Line eclipse mapping of an accretion disk wind' 3579 `The UV orbital lightcurve of the X-ray binary X1822-371' Co-I ROBINSON is a member of the High-Speed Photometer IDT and was actively involved in Orbital and Science Verification of the instrument. So far, he has received data from two GTO science programs: Program GTO-3253 "Optical and Ultraviolet Observations of Radio Pulsars" Results have been presented at two international meetings, and a paper reporting the results has been submitted to the Astrophysical Journal. The program is not related to this proposal. Program GTO-1092 "Eclipses of Cataclysmic Variable Stars" Preliminary results were presented at the Columbus AAS meeting. The program is only peripherally related to this proposal. ROBINSON is also a Co-PI on two GO programs: Program 3600 "Oscillations, Flaring and Tomography of AE Aquarii" The observations have not yet been scheduled. The program is closely related to this proposal. Program GO-3683 "Accretion Disk Mapping in Eclipsing Cataclysmic Variables" The observations have not yet been scheduled. The program is only peripherally related to this proposal. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). A SPARC-2 workstation will be assigned to this project. Facilities for contemporaneous ground based observations will be provided by McDonald Observatory. ------------------------------------------------------------------------------------ 11. Address Information Name: COEL HELLIER Category: PI Institution: 3550 Address: Department of Astronomy, University of Texas City: Austin State: TX Zip Code: 78712 Country: USA Telephone: 512 471 3000 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4656c [ 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 AO-PSC A,151,154,161,906 PLATE-ID=03U1, 2000 1 V=13.4 +/- 0.3 GSC5238-0223 RA = 22H 55M 17.9S +/- 1", 2 F-LINE(1549) = 2.4 +/- 0.5 E-13 DEC = -03D 10' 39" +/- 1" 3 W-LINE(1549) = 15 +/- 3 4 F-CONT(1520) = 1.5 +/- 0.5 E-13 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4656c [ 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 AO-PSC HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 4 1 ONBOARD ACQ FOR 2- 9 CYCLE 3 GROUP 1-13 WITHIN 30H ------------------------------------------------------------------------------------------------------------------------------------ 2 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 3 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 4 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 5 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4656c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 6 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 7 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 8 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 9 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 10 AO-PSC HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 4 1 ONBOARD ACQ FOR 11 -13 CYCLE 3 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4656c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 12 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ 13 AO-PSC HRS RAPID 2.0 G160M 1548 SAMPLE- 1 38M 10 2 1 CYCLE 3 TIME=10.0 20M 3 4 Comments: EXPOSURE TIME IS NOT CALCULATED SOLELY ON SIGNAL TO NOISE RATIO , THE 6.9H IS ALSO CALCULATED TO COVER 30 SPIN CYCLES AND 2 ORBITAL CYCLES OF AO PSC, SEE QUESTION 3 FOR FULL DETAILS. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4656c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SAMPLE-TIME=10.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.90 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2-9; CYCLE 3; GROUP 1-13 WITHIN 30H CYCLE 3 ONBOARD ACQ FOR 11-13; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names AO-PSC GSC5238-0223 ------------------------------------------------------------------------------------------------------------------------------------