8305( 4) - 07/14/99 11:33 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8305 Version: 4 Check-in Date: 14-Jul-1999 11:32:06 1.Proposal Title: Two Post-Common-Envelope Binaries in the Hyades Cluster ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Howard Bond Space Telescope Science Institute CoI: Dr. Edward M. Sion Villanova University N CoI: Dr. Fuhua Cheng Villanova University N CoI: Dr. Karen G. Schaefer Towson University N ------------------------------------------------------------------------------------ 5. Abstract V471 Tau and HZ 9 are two detached binaries that are members of the Hyades cluster and consist of hot white dwarfs with main-sequence K-M companions. They have emerged from common- envelope interactions which drastically reduced their initially wide separations. For V471 Tau we will use STIS to confirm and further explore the host of fascinating phenomena that we have found using GHRS in a very limited spectral range near Lyman-Alpha. We have shown that the white-dwarf component, which rotates with a 9.25-min period, has a polar cap of accreted metals. The implied accretion rate from the dK wind, however, is so low that a magnetic propeller mechanism must be rejecting most of the material that attempts to accrete. In fact, we tentatively find Zeeman splitting of a metallic line, implying a field strength of ~350 kG, sufficient for the propeller mechanism to work. The GHRS radial velocities imply a white dwarf mass of 0.85 M_\odot, paradoxically much too massive for the star's high temperature. STIS, whose echelle can cover the entire UV spectrum from 1150-1710 Angstrom, is ideal for confirming and extending all of these exciting findings. We will also use STIS to obtain the first high-resolution UV spectra of HZ 9, to see to what extent the above phenomena occur in a non- magnetic system which is otherwise remarkably similar to V471 Tau, and to determine accurate component masses. ------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 2] Observations Description ------------------------ We will use STIS to observe each target, V471 Tau and HZ 9, 4 times, for a grand total of 8 HST orbits. With acquisitions and overheads, we can obtain about 28 min of science exposure time per HST orbit. V471 Tau: We will observe twice at each of the two orbital quadratures, using the E140M echelle and MAMA detector to cover the 1150--1710 Angstrom\ region. The binary orbital phasing is extremely well-known from the ground due to the sharp eclipses. Continuum fluxes are very well known for the hot component from our IUE and HST GHRS observations. Assuming a nominal 28-min integration time for each of the 4 visits, the STIS Exposure Time Calculator (ETC) predicts each 28-min spectrum will have a S/N per pixel of 14 (at 1400 AA). This will be a quite appropriate S/N for the purpose of measuring radial velocities. The spectra will be taken in time-tagged mode so that they can be sorted into rotational phase bins on the 9.25-min rotational period of the white dwarf. If we sort into 4 phase bins, then each individual phase-resolved spectrum will have the same S/N described above, which will again be very generous for our goal of searching for phase-variable, Zeeman-split metallic lines, especially because the pixel resolution is so high (the nominal scale is ~0.016 Angstrom/pixel) that we can sum over several (5-10) pixels. (For comparison, our GHRS spectra had a scale of 0.07 Angstrom/diode, and the white- dwarf lines will have an intrinsic FWHM of ~0.2 Angstrom.) HZ 9: We will likewise observe HZ 9 twice at each of the two orbital quadratures. By combining the RV observations of Lanning & Pesch and of Stauffer, we know the phasing well enough to schedule the observations. Since this white dwarf is cooler than that in V471 Tau, its UV flux is lower, and the E140M echelle will yield a S/N per pixel at 1400 Angstrom\ of 8 for a 28-min exposure. This improves to S/N = 24 per resolution element if we sum over 9 pixels (0.14 Angstrom) in the dispersion direction. This will again be very adequate for our scientific aims. Note that (for both targets) we can sum in (Lambda-Lambda_0) space over all metallic lines that have the same Lande g factor, in order to improve greatly the detectability of Zeeman splitting. Total orbit request: 8 orbits Real Time Justification ----------------------- As noted above, the observations are time-critical, because they must be scheduled at the orbital quadratures of both binary systems. Given their short orbital periods, there are many opportunities for such scheduling. Calibration Justification ------------------------- Additional Comments ------------------- PLEASE NOTE THAT THE BINARY STAR PHASES ARE HELIOCENTRIC, NOT GEOCENTRIC. The correction from heliocentric to geocentric can be as large as 8 minutes. Science exposure times have been adjusted for the maximum length possible in one orbit. Should be lengthened further if more time become available in the orbit, e.g., if the Automatic Wavecal could be done after the science exposure instead of before it. ------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 3] Data Distribution Paper Products: YES Media: ELECTRONIC Blocking Factor: 10 Ship To: STSCI Ship Via: Email: bond@stsci.edu ------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 V471TAU STAR, DA, K V-IV, RA = 03H 50M 24.88S +/- 0.7", J2000 V = 9.4 INTERACTING BINARY DEC = +17D 14' 48.3" +/- 0.7", B-V = 0.9 PLATE-ID=00FH Comments: Coordinates updated 18-feb-99 from Phase II DSS. P.M. updated from SIMBAD. V, B-V from Ibanoglu 1994. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1982.96 0.0091 -0.0233 0.0 2 HZ9 STAR, DA, M V-IV, RA = 04H 32M 23.72S +/- 0.7", J2000 V = 13.95 INTERACTING BINARY DEC = +17D 45' 03.5" +/- 0.7", B-V = 0.33 PLATE-ID=000P Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1982.96 0.0 0.0 0.0 8305( 4) - 07/14/99 11:33 - [ 5] Visit: 01 Visit Priority: Visit Requirements: PERIOD 0.52118294D AND ZERO-PHASE JD2450062.7664 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC. Ephemeris is from E. Guinan, 1999. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V471TAU STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 3.0 S ONBOARD ACQ FOR 2 CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 V471TAU STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=240 1 32.7 M PHASE 0.20 TO 0.256 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PERIOD 0.52118294D AND ZERO-PHASE JD2450062.7664 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V471TAU STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 3.0 S ONBOARD ACQ FOR 2 CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 V471TAU STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=240 1 32.7 M PHASE 0.20 TO 0.256 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 7] Visit: 03 Visit Priority: Visit Requirements: PERIOD 0.52118294D AND ZERO-PHASE JD2450062.7664 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V471TAU STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 3.0 S ONBOARD ACQ FOR 2 CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 V471TAU STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=240 1 32.7 M PHASE 0.70 TO 0.756 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 8] Visit: 04 Visit Priority: Visit Requirements: PERIOD 0.52118294D AND ZERO-PHASE JD2450062.7664 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V471TAU STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 3.0 S ONBOARD ACQ FOR 2 CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 V471TAU STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=240 1 32.7 M PHASE 0.70 TO 0.756 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 9] Visit: 05 Visit Priority: Visit Requirements: PERIOD 0.56433022D AND ZERO-PHASE JD2443456.95345 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC, based on 1999 WIYN velocities. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HZ9 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S ONBOARD ACQ FOR 2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HZ9 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=1002 1 33.4 M PHASE 0.20 TO 0.26 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 10] Visit: 06 Visit Priority: Visit Requirements: PERIOD 0.56433022D AND ZERO-PHASE JD2443456.95345 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC, based on 1999 WIYN velocities. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HZ9 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S ONBOARD ACQ FOR 2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HZ9 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=1002 1 33.4 M PHASE 0.20 TO 0.26 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 11] Visit: 07 Visit Priority: Visit Requirements: PERIOD 0.56433022D AND ZERO-PHASE JD2443456.95345 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC, based on 1999 WIYN velocities. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HZ9 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S ONBOARD ACQ FOR 2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HZ9 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=1002 1 33.4 M PHASE 0.70 TO 0.76 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 12] Visit: 08 Visit Priority: Visit Requirements: PERIOD 0.56433022D AND ZERO-PHASE JD2443456.95345 On Hold Comments: Additional Comments: The binary ephemeris is HELIOCENTRIC, based on 1999 WIYN velocities. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HZ9 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S ONBOARD ACQ FOR 2 CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HZ9 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=1002 1 33.4 M PHASE 0.70 TO 0.76 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8305( 4) - 07/14/99 11:33 - [ 13] Summary Form for Proposal 8305 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 0.2X0.2 F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BUFFER-TIME=240 BUFFER-TIME=1002 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 0.52118294D AND ZERO-PHASE JD2450062.7664 ONBOARD ACQ FOR 2 PHASE 0.20 TO 0.256 PHASE 0.70 TO 0.756 PERIOD 0.56433022D AND ZERO-PHASE JD2443456.95345 PHASE 0.20 TO 0.26 PHASE 0.70 TO 0.76 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names V471TAU HZ9 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------