Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5347 Report Date: 18-Jul-95:17:12 Version: ********** Check-in Date: ********** 1.Proposal Title: ROTATION RATES OF WHITE DWARFS AND BOUNDARY LAYERS IN CATACLYSMIC VARIABLES: CYCLE4 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 Janet H Wood UNIVERSITY OF KEELE UK 011-44-782-583 ------------------------------------------------------------------------------------ 7. Abstract A long standing problem in cataclysmic variables has been the lack of observed flux from boundary layers in non-magnetic systems. This is frequently explained as due to the rapid rotation of the white dwarf. Accretion of only 0.1 solar masses is enough to spin up a white dwarf almost to its breakup velocity. It then reaches an equilibrium rotation rate where mass is accreted but does not add angular momentum to the white dwarf. However, no observational confirmation of such rapid rotation rates has yet been obtained. We propose to observe white dwarf photospheric lines in the UV and use model atmospheres to determine the rotational broadening. If we find that rapidly rotating white dwarfs are present this explanation for the lack of flux from boundary layers is very likely to be true. We will observe 2 dwarf novae with HRS and G160M covering 1382-1415 Angstroms. We chose as our targets the brightest (in the UV) dwarf novae which are not eclipsing, have infrequent outbursts, and for which there is evidence of the presence of Si IV 1393, 1402 absorption in IUE spectra. As a bonus of these observations we will make the first ever radial velocity measurements directly from the white dwarfs in cataclysmic variables. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5347 PI: Janet H Wood Proposal Title: ROTATION RATES OF WHITE DWARFS AND BOUNDARY LAYERS IN CATACLYSMIC VARIABLES: CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Janet H Wood 8030 UK X Thomas Marsh 8058 UK X Edward L Robinson 3550 US ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will obtain high resolution spectroscopy of the dwarf novae CM Del and AH Her with the HRS using the LSA. We will use the G160M grating with central wavelength 1398.5 Angstroms to cover a wavelength range from 1382 to 1415 Angstroms. This wavelength range covers the Si IV resonance doublet at 1393, 1402 Angstroms. These absorption lines are produced in the white dwarfs' photospheres. We will use RAPID readout mode with integration times of 12.75s. This will allow us to investigate any variability in the objects and means we will not smear out the observed lines due to the white dwarf's orbital motion. As a bonus this data will also allow us to measure the radial velocity of each white dwarf from the absorption line cores; the first time a direct measurement has been made in a cataclysmic variable. IUE observations of CM Del and AH Her have shown that they both have flux densities of 3.2 x 10 ^-26 ergs/s/cm^2/Hz at 1400 Angstroms. With the HRS and G160M grating we therefore expect count rates of 108 counts/diode in one hour from each object using the LSA. The dark count rate is 28.8 counts/diode in one hour. The dispersion of 0.07 Angstroms/diode will easily resolve the line cores. If the white dwarfs are rotating rapidly we expect line core widths of a few Angstroms. Thus, without rebinning with a total integration time of 95mins on AH Her and 91.5mins on CM Del we will obtain signal-to-noise ratios of 12 and 11, respectively. The observations of each star can be obtained in one visit with observations continuing between Earth occultations until the required time on target has been reached. Our primary aim, to measure v sini, is not affected by what part of the orbit is observed. The orbital periods of CM Del and AH Her are 3.9hr and 6.2hr respectively. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is essential as its large mirror and efficient instruments mean it is the only telescope capable of making these high resolution UV observations, and the only one capable of achieving a high signal-to-noise. This project cannot be done using optical data because the accretion disc dominates the light in the optical even in quiescent dwarf novae. In the UV quiescent accretion discs are very faint and the white dwarf's spectrum can be observed. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Page 3 ------------------------------------------------------------------------------------ 9. Description of previous HST work. Program GO-3836 "Spectroscopic Observations of the Exposed White Dwarfs in the Dwarf Novae WZ Sagittae, U Geminorum and VW Hydri" Sion, Szkody, Gilliland, Long, Pringle, Horne, Wood This program is related to the current proposal. Program GO- 2380 "Instabilities in Accretion Disks and the Outbursts of Dwarf Novae": Horne and Marsh. Program GO-3683 "Accretion Disk Mapping in Cataclysmic Variables" Horne et al. Program GO-3600 "Oscillations, Flaring and Tomography of AE Aquarii": Horne, Marsh, Robinson, Wood. Program GO-3824 "A Search for Silicon and Carbon in GP Com": Wood, Marsh, Lambert, Horne. Program GO-3578 "Line Eclipse mapping of an Accretion Disk Wind" Mason, Drew, Cordova, Mauche, Horne, Marsh Program GO-4271 "Testing the Star-Disk Connection: CIV and MGII Maps of Accretion Disks" Horne, Marsh, Rutten, Saar GTO time on the HSP for several projects. Bless, Dolan, Elliot, Robinson, van Citters. "HST Observations of the Dwarf Nova Z Cha through its Outburst Cycle" Wood, Robinson, Dolan, Elliot, van Citters in "Annals of the Israel Physical Society", Vol 10, ed. Regev, Shaviv, p19 (1993). "HST Observations of the Eclipsing Dwarf Nova OY Carinae" Marsh in Annals of the Israel Physical Society", Vol 10, ed. Regev, Shaviv, p7, (1993). "HST HRS Spectroscopy of U Gem in Quiescence: Rotation Rate of White Dwarf" Sion, Huang, Long, Szkody, Horne 1993, BAAS, 25,909. "HST High Speed Photometer Observations of the Crab Pulsar", Biggs, Percival, Bless, Dolan, Elliot, Nelson, Robinson, Taylor, van Citters, in Physics of Isolated Pulsars, ed. Riper, Epstein and Ho, CUP, 1993, in press. "The Crab Pulsar in the Visible and UV with 10microsec Time Resolution" Percival, Biggs, Dolan, Robinson, Taylor, Bless, Elliot, Nelson, Ramseyer, van Citters, Zhang, Ap.J., 407, 276. 1993. "High Speed UV Photometry of HD 60435", Taylor, Nelson, Bless, Dolan, Elliot, Percival, Robinson, van Citters, Ap.J. Lett. submitted, 1993. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Data analysis will be done using the STARLINK computing facilities at Keele and Oxford and on a Sparcstation II at the University of Texas. The University of Texas will provide facilities for a student. ------------------------------------------------------------------------------------ 11. Address Information Name: JANET H WOOD Category: PI Institution: 8030 Address: DEPARTMENT OF PHYSICS KEELE UNIVERSITY City: KEELE State: Zip Code: Country: UK Telephone: 011-44-782-583341 Telex (or e-mail): 36113 UNKLIB G/JHW%UK.AC.KEELE.PH.STARLIN ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5347 [ 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 CM-DEL A,149,161,906 PLATE-ID = 02UR, 2000.0 1 V=15.3+/-0.1 RA = 20H 24M 56.92S +/- 1 B-V=0.10+/-0.01 0.07S, 2 E(B-V)=0.08+/-0.01 DEC = +17D 17' 54.52" +/- 3 F-CONT(1400)=49+/-3E-15 1.0" Comments: ALL FLUXES ARE FOR QUIESCENCE. IN OUTBURST BRIGHTENS BY 2-3 MAGNITUDES BUT ITS UNLIKELY TO BE IN OUTBURST. ------------------------------------------------------------------------------------------------------------------------------------ 2 AH-HER A,149,161,906 PLATE-ID = 02BA, 2000.0 1 V=14.7+/-0.1 GSC2049.0111 RA = 16H 44M 09.99S +/- 1 B-V=0.10+/-0.01 5 0.07S, 2 E(B-V)=0.03+/-0.01 DEC = +25D 15' 01.9" +/- 3 F-CONT(1400)=49+/-3E-15 0.8" Comments: ALL FLUXES ARE FOR QUIESCENCE. IN OUTBURST BRIGHTENS BY 2-3 MAGNITUDES BUT ITS UNLIKELY TO BE IN OUTBURST. COORDS FROM GUIDE STAR CATALOGUE. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5347 [ 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 CM-DEL HRS ACQ 2.0 MIRROR-N2 1 72S 1 1 CYCLE 4 / 1-3 ONBOARD ACQ FOR 2 GROUP 1-3 NO GAP Comments: STEP-TIME=8S 1000 counts expected ------------------------------------------------------------------------------------------------------------------------------------ 2 CM-DEL HRS ACQ/ 2.0 MIRROR-N2 1 714S 1 1 ONBOARD ACQ FOR 3 PEAKUP Comments: STEP-TIME=7S ------------------------------------------------------------------------------------------------------------------------------------ 3 CM-DEL HRS ACCUM 2.0 G160M 1398.5 12 410S 10 3 1 82M ------------------------------------------------------------------------------------------------------------------------------------ 4 AH-HER HRS ACQ 2.0 MIRROR-N2 1 27S 1 1 CYCLE 4 / 4-6 ONBOARD ACQ FOR 5 GROUP 4-6 NO GAP Comments: STEP-TIME=3S 1000 COUNTS EXPECTED ------------------------------------------------------------------------------------------------------------------------------------ 5 AH-HER HRS ACQ/ 2.0 MIRROR-N2 1 306S 1 1 ONBOARD ACQ FOR 6 PEAKUP Comments: STEP-TIME=3S ------------------------------------------------------------------------------------------------------------------------------------ 6 AH-HER HRS ACCUM 2.0 G160M 1398.5 12 414S 11 3 1 82.8M ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5347 [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 1-3; ONBOARD ACQ FOR 2; GROUP 1-3 NO GAP; ONBOARD ACQ FOR 3 CYCLE 4 / 4-6; ONBOARD ACQ FOR 5; GROUP 4-6 NO GAP; ONBOARD ACQ FOR 6 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names CM-DEL AH-HER GSC2049.01115 ------------------------------------------------------------------------------------------------------------------------------------