6628( 3) - 02/14/96 10:36 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6628 Version: 3 Check-in Date: 14-Feb-1996 10:31:10 1.Proposal Title: THE WIND AND PHOTOSPHERE OF THE UNIQUE DO WHITE DWARF RE\\ J0503-289 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Martin Barstow University of Leicester CoI: Dr. Jay Holberg University of Arizona N CoI: Dr. Edward Sion Villanova University N CoI: Dr. Ivan Hubeny Goddard Space Flight Center N CoI: Dr. Thierry Lanz Goddard Space Flight Center N ------------------------------------------------------------------------------------ 6. Abstract We propose to obtain high S/N GHRS spectra of the key He-rich white dwarf RE J0503- 289. These observations have two principal aims. The first is to investigate the phenomenon of mass loss in this star. Excluding planetary nebulae nuclei, RE J0503- 289 is the only white dwarf in which evidence of ongoing mass loss has been observed with IUE. However, the reported detection is near the limit of the sensitivity of IUE preventing study of the wind during its less intense periods. Mass loss may well be the missing ingredient in the theoretical description of heavy element abundances in white dwarfs. RE J0503-289 is the only known white dwarf where this effect can be studied as an on going phenomenon. The second aim is to search for Fe and Ni in the photosphere of this star. The presence of these elements is required to explain the large flux deficit observed in the EUV. Detailed models, including those elements so far detected (C, N, O and Si), substantially over predict EUV flux levels. RE J0503- 289 is also the only DO white dwarf for which a joint analysis of EUV and UV data will be possible and for which we can conduct a definitive study of the composition and structure of the photosphere. ------------------------------------------------------------------------------------ 6628( 3) - 02/14/96 10:36 - [ 2] Observations Description ------------------------ The proposed GHRS observations for RE J0503-289 are given below. The spectral coverage, spectral configuration, signal- to-noise, exposure time and ions expected to be seen are given for each spectral setup. All spectra will be obtained using the standard FP-SPLIT=4 option. This is to minimize the effects of fixed pattern detector noise and to easily identify any diode dropouts, which could produce artificial absorption features. The required S/N of 20 corresponds to ~ 400 counts per data point, where each diode is quarter stepped (each diode is used 4 times in a comb addition to produce the spectrum). This represents STEP-PATTERN=5 for the G160M grating.In all we need exposures for each of two wavelength ranges. beginitemize em 1235-1270Angstrom : exposure (S/N=20) = \\ 7 min: NV + FeV/FeVI/NiV/NiVI em 1370- 1405Angstrom : exposure (S/N=20) = 10 min: OV/SiIV + FeV/FeVI/NiV/NiVI enditemize . In addition we will obtain a 21 minute exposure of HeII to allow a detailed cross reference of the HST data with that already obtained for IUE. The above exposures are combined into one visit of two orbits. With a visibility of 53min per orbit, three exposures in NV and OV ranges are possible, after accounting for observation overheads. Hence the total time coverage will be about 150min. Real Time Justification ----------------------- None None Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6628( 3) - 02/14/96 10:36 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 REJ0503-289 STAR,WDO RA=05H 03M 55.39S +/- 0.2S, DEC= J2000 V = 13.90+/-0.01 -28D 54' 36.4" +/- 0.25", PLATE- B-V = -0.35+/-0.01 ID=04WB F-CONT(1400)=1.2+/-0.1e-12 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1978.77 0.0 0.0 0.0 6628( 3) - 02/14/96 10:36 - [ 4] Visit: 01 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 REJ0503-289 HRS ACQ 2.0 MIRROR-N2 1 1.8S ONBOARD ACQ FOR 11-17 Comments: expected count rate = 22,500 c/s ------------------------------------------------------------------------------------------------------------------------------------ 11 REJ0503-289 HRS ACCUM 2.0 G160M 1370- COMB=FOUR,STEP- 1 652.8S 1405 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 12 WAVE HRS ACCUM SC2 G160M 1235- SPYBAL=YES 1 54.4S 1270 Comments: WAVECAL for 1235-1270 region ------------------------------------------------------------------------------------------------------------------------------------ 13 REJ0503-289 HRS ACCUM 2.0 G160M 1235- COMB=FOUR,STEP- 1 435.2S 1270 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 14 REJ0503-289 HRS ACCUM 2.0 G160M 1370- COMB=FOUR,STEP- 1 544S 1405 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 15 REJ0503-289 HRS ACCUM 2.0 G160M 1620- COMB=FOUR,STEP- 1 979.2S 1655 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 16 REJ0503-289 HRS ACCUM 2.0 G160M 1370- COMB=FOUR,STEP- 1 544S 1405 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 17 REJ0503-289 HRS ACCUM 2.0 G160M 1235- COMB=FOUR,STEP- 1 435.2S 1270 PATT=5,FP- SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 6628( 3) - 02/14/96 10:36 - [ 5] Summary Form for Proposal 6628 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters COMB=FOUR STEP-PATT=5 FP-SPLIT=STD SPYBAL=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 11-17 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names REJ0503-289 WAVE ------------------------------------------------------------------------------------------------------------------------------------