8712( 2) - 03/14/00 16:10 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8712 Version: 2 Check-in Date: 13-Jan-2000 09:45:41 1.Proposal Title: The wind accretion wake in a detached binary system ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Thomas Dumm Eidgenossiche Technische Hochschule (ETH) CoI: Prof. Harry Nussbaumer Swiss Federal Institute of Technology N CoI: Dr. Hansruedi Schild Swiss Federal Institute of Technology N CoI: Dr. Rolf Walder Swiss Federal Institute of Technology N CoI: Dr. Doris Folini Swiss Federal Institute of Technology N CoI: Prof. Ed Sion Villanova University N ------------------------------------------------------------------------------------ 5. Abstract RW Hya (= HD 117970) is the only known detached binary system, where direct observational evidence for wind accretion onto a white dwarf is found. STIS UV observations will enable us to advance our knowledge in a field which has for long had to remain a theoretical subject. RW Hya is an eclipsing system containing a mass -losing M-giant and a hot white dwarf on circular orbits (370 days). Close to quadrature, Rayleigh attenuation of the white dwarf UV-continuum has revealed a strong temporary increase in the column density of neutral hydrogen in the line of sight. This behaviour is a forceful indication for an accretion wake trailing the white dwarf. With the proposed STIS/UV observations of RW Hya, we can for the first time tomographically map the structure of an accretion wake. The shape of the accretion wake depends on the properties of the unperturbed M-giant wind as well as on hydrodynamical processes in the wake. We will therefore be able to study both, M- giant wind acceleration and dynamics of shocked ionized flows. The proposed set of spectra will thus yield stringent boundary conditions for refined hydrodynamical wind accretion simulations in detached binary systems. ------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 2] Observations Description ------------------------ We plan to take spectra of the point source RW~Hya, at phases when the white dwarf continuum gets Rayleigh attenuated by the accretion wake. To observe Rayleigh attenuation we need to observe RW~Hya in the range 1150Angstrom < Lambda < 1700Angstrom. We require the echelle grating E140M with a resolution of 45'000, slit 0.2"* 0.2". This allows to clearly define the continuum level in the presence of numerous ionFeii absorption lines (e.g. Shore & Aufdenberg 1993, Dumm et al. 1999a). We have calculated the exposure time based on the HST GHRS spectrum taken close to the phase of the proposed observations (Fig.1). The required S/N~20 in the continuum at Lambda 1450, demands an exposure time of approx 2000 seconds. During an HST orbit RW Hya has a total visibility of 53 minutes. With a total overhead of 20 minutes (Guide star acq.: 6 min, target acquisition 6 minutes, overhead for MAMA spectrograph: 8 min) there remain 2000 seconds for observations. Thus, one orbit is the time needed for one observation. The count rates at the position of the emission lines will stay well below the local and global MAMA count rate limits. The study of the accretion wake requires a good coverage of the UV continuum attenuation event. We ask for repeated observations spaced at intervals of 0.01 (~ 4 days). The first observation should be done at Phi=0.76 the last one at Phi=0.83. This results in a total of 8 observations, thus 8 orbits. Real Time Justification ----------------------- As the orbital period of RW Hya is 370.3 days, the Rayleigh attenuation event takes place only once a year. During Cycle 9 this occurs in April/May 2001. The first observation should be done between April 12 and April 13, 2001 the last one between May 10 and May 11, 2001. (NOTE: In case the observations can be done at the end of Cycle 8, the windows for the 8 visits would shifted 5 days in advance, eg. first vistit could be done between April 7, and April 8, 2000 , the last vist could be done between May 5, and May 6, 2000 Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD117970 STAR, SYMBIOTIC STAR, RA=13H 34M 18.17S +/- 0.5", DEC= J2000 V = 12.9 V = 9.0+/-0.8 INTERACTING BINARY, -25D 22' 48.9" +/- 0.5", PLATE- B-V = 1.3+/-0.5 EMISSION LINE STAR ID=04LM E(B-V) = 0.05+/-0.05 F(1200)=1.5+/-0.2e-12 F(1400)=1.2+/-0.2e-12 F(1600)=0.8+/-0.2e-12 F-LINE(1550)=4+/-1e-10 W-LINE(1550)=0.5+/-0.1 Comments: The UV-fluxes are taken from IUE spectra around the phase when RW Hya is brightest. The strongest emission line in the UV-spectrum is the CIV 1548, 1550 duplet. The given flux is the total flux for both lines together. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1976.417 -0.0010 0.0221 0.0015 8712( 2) - 03/14/00 16:10 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 12-Apr-2001:00:00:01.0 AND 13-Apr-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 16-Apr-2001:00:00:01.0 AND 17-Apr-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 6] Visit: 03 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 20-Apr-2001:00:00:01.0 AND 21-Apr-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 7] Visit: 04 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 24-Apr-2001:00:00:01.0 AND 25-Apr-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 8] Visit: 05 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 28-Apr-2001:00:00:01.0 AND 29-Apr-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 9] Visit: 06 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 02-May-2001:00:00:01.0 AND 03-May-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 10] Visit: 07 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 06-May-2001:00:00:01.0 AND 07-May-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 11] Visit: 08 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 10-May-2001:00:00:01.0 AND 11-May-2001:00:00:01.0 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD117970 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 5 S CD ------------------------------------------------------------------------------------------------------------------------------------ 30 HD117970 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2100 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8712( 2) - 03/14/00 16:10 - [ 12] Summary Form for Proposal 8712 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% BETWEEN 12-Apr-2001 00 00 01.0 AND 13-Apr-2001 00 00 01.0 SCHED 100% BETWEEN 16-Apr-2001 00 00 01.0 AND 17-Apr-2001 00 00 01.0 SCHED 100% BETWEEN 20-Apr-2001 00 00 01.0 AND 21-Apr-2001 00 00 01.0 SCHED 100% BETWEEN 24-Apr-2001 00 00 01.0 AND 25-Apr-2001 00 00 01.0 SCHED 100% BETWEEN 28-Apr-2001 00 00 01.0 AND 29-Apr-2001 00 00 01.0 SCHED 100% BETWEEN 02-May-2001 00 00 01.0 AND 03-May-2001 00 00 01.0 SCHED 100% BETWEEN 06-May-2001 00 00 01.0 AND 07-May-2001 00 00 01.0 SCHED 100% BETWEEN 10-May-2001 00 00 01.0 AND 11-May-2001 00 00 01.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD117970 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------