7390( 18) - 03/09/99 12:36 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7390 Version: 18 Check-in Date: 09-Mar-1999 12:36:12 1.Proposal Title: High resolution UV spectroscopy of the extra-ordinary centr al star of Abell 35 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Janet Drew Imperial College of Science, Technology & Medicine CoI: Anna Gatti Imperial College London N CoI: Rene Oudmaijer Imperial College London N CoI: Tony Lynas-Gray Oxford University N CoI: Thomas R. Marsh Southampton University N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain images and undertake a UV spectral study of the extra-ordinary binary central star of the old Planetary Nebula Abell 35. This system consists of BD -22D3467, a rapidly rotating G8III-IV star which dominates the optical light, and a white dwarf, probably belonging to the PG1159 class, that dominates the UV flux. The orbital parameters of the system are poorly constrained. The binary has not yet been spatially-resolved but may present a separation of a few tenths of an arcsecond. ------------------------------------------------------------------------------------ 7390( 18) - 03/09/99 12:36 - [ 2] Observations Description ------------------------ We propose to obtain: 1) WFPC2 images of the system to determine a value for or an upper limit on the separation of the binary components (visit 01, 1 orbit). These data will also provide astrometry relevant to visit 02. 2) high resolution UV spectroscopy of the white dwarf exciting the nebula Abell 35 (visit 02, 4 orbits). BD-22D3467, a G8III/IV star, dominates the spectrum longwards of about 3500 Ang whereas the white dwarf dominates shortward of 3000 Ang. Because the binary has not been resolved from the ground or space (IUE), BD-22D3467 is the only component to which an accurate position has been assigned. IUE data on the system sets an upper limit of approximately 1" on the binary separation. As evidence is accumulating that this is a long period binary, it would not be suprising to find that the two stars are separated by as much as a few tenths of an arcsecond. DESCRIPTION OF VISIT 01: PC images of the binary system will be taken with three filters, F300W (white dwarf flux predominant), F366W (both components present at approximately equal flux) and F547M (only giant star and field stars). Dithering is required for F300W and F336W to maximize resolution. Additional F547M observations will be used to improve the signal to noise of field star in order to better tie the binary in a field star reference frame. We request all the images obtained in both the WF and the PC during this visit. DESCRIPTION OF VISIT 02: The E140M grating of the STIS echelle mode (Mama detectors, 0.2X0.2 aperture) will be employed to obtain high resolution UV spectroscopy of the white dwarf star. While the ACQ will be made on the giant companion using the STIS/CCD, the ACQ/PEAK MUST BE PERFORMED ON THE WHITE DWARF USING THE NOT YET IMPLEMENTED MAMA ACQ/PEAK capability. Should we use the CCD dispersed light peak up, the white dwarf could only be distinguished from the nearby giant with the G230MB grating. Based on the calibrated IUE flux, the spectroscopic ETC predicts that the 80000 counts recommended for the peak up would take 800 seconds to accumulate. All remaining available time in the 4 orbits is to be used to accumulate a UV spectrum. We estimate that we will be able to achieve a S/N ratio in the region of 30. Real Time Justification ----------------------- a) The pre-acquisition WFPC2 imaging (visit 01) must be taken before the STIS spectroscopy. VISIT 02 will be kept on hold until the astrometry of the binary system has been determined. b) VIST 02 requires the MAMA ACQ/PEAK capability and will be kept on hold until this has been full implemented. Calibration Justification ------------------------- None Additional Comments ------------------- None ------------------------------------------------------------------------------------ 7390( 18) - 03/09/99 12:36 - [ 3] Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7390( 18) - 03/09/99 12:36 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 BD-22D3467 STAR, PLANETARY NEBULA RA=12H 53M 32.86S +/- 0.1S, DEC= J2000 V = 9.58+/-0.40 CENTRAL STAR, -22D 52' 22.3" +/- 0.5", PLATE- TYPE=G8III INTERACTING BINARY, FK ID=04LL E(B-V) = 0.10+/-0.10 COMAE STAR, PULSATING B-V = 0.904+/-0.006 U-B = 0.349+/-0.026 Comments: BD-22D3467 is the giant companion (G8III/IV) to the central star of the PN Abell 35. It dominates the optical flux from the system. Because the binary has not been resolved from ground or space (IUE) only the position of BD-22D3467 has been determined. The quoted position is taken from GSC catalogue: star is saturated in GSC plates. The proper motion is quoted from the Hipparcos Main catalogue. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1976.412 -0.00441 -0.015 0.0 2 S-BD-22D3467 STAR, PLANETARY NEBULA RA-OFF=0.0S+/- 0.001S, DEC-OFF=- J2000 F(1600)=0.5+/-0.1e-12 CENTRAL STAR, PG1159 0.1"+/- 0.01", FROM 1, PLATE- V = 9.58+/-0.40 STAR ID=04LL 3 N-BD-22D3467 STAR, PLANETARY NEBULA RA-OFF=0.0S+/- 0.001S, DEC- J2000 F(1600)=0.5+/-0.1e-12 CENTRAL STAR, PG1159 OFF=0.1"+/- 0.01", FROM 1, PLATE V = 9.58+/-0.40 STAR -ID=04LL 7390( 18) - 03/09/99 12:36 - [ 5] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: The PC images of the binary system will be used to determine the offset, if measurable, of the white dwarf from the giant companion. These observations must precede the STIS observations of visit 02. The three filters are used to separate the giant companion from the white dwarf star. Dithering is introduced to maximize resolution. Exposure 40 is used to increase the S/N of surrounding field stars. We ask that the WF and PC images are all read out as we will use the WF data to establish field star positions. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 BD-22D3467 WFPC2 IMAGE PC1 F300W DITHER-TYPE=BOX 1 60 S ------------------------------------------------------------------------------------------------------------------------------------ 20 BD-22D3467 WFPC2 IMAGE PC1 F336W DITHER-TYPE=BOX 1 12 S ------------------------------------------------------------------------------------------------------------------------------------ 30 BD-22D3467 WFPC2 IMAGE PC1 F547M 3 0.4 S ------------------------------------------------------------------------------------------------------------------------------------ 40 BD-22D3467 WFPC2 IMAGE PC1 F547M 2 1 S ------------------------------------------------------------------------------------------------------------------------------------ 7390( 18) - 03/09/99 12:36 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ON HOLD FOR 01 On Hold Comments: Waiting for early acquisition data from visit 01. On hold waiting for MAMA ACQ/PEAK capabilities. Additional Comments: The offset of star125332-225222 must be calculated from visit 01 prior to the scheduling of visit 02. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 BD-22D3467 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 0.4 S ONBOARD ACQ FOR 20 CD ------------------------------------------------------------------------------------------------------------------------------------ 20 S-BD-22D346 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=350 1 2050 S 7 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 S-BD-22D346 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=350 1 2800 S 7 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 N-BD-22D346 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=350 1 2740 S 7 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 50 N-BD-22D346 STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=350 1 2740 S 7 UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 7390( 18) - 03/09/99 12:36 - [ 7] Summary Form for Proposal 7390 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 F25ND3 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=BOX ACQTYPE=POINT BUFFER-TIME=350 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD FOR 01 ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F300W F336W F547M MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names BD-22D3467 S-BD-22D3467 N-BD-22D3467 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------