9159( 5) - 09/14/01 10:51 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9159 Version: 5 Check-in Date: 14-Sep-2001 10:50:32 1.Proposal Title: Test of a New Observational Method for Stellar Seismology ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: M. Sean O'Brien Space Telescope Science Institute CoI: Dr. Howard E. Bond Space Telescope Science Institute N CoI: Dr. Steven D. Kawaler Iowa State University N CoI: Dr. Stefan Dreizler Institut fuer Astronomie und Astrophysik N ------------------------------------------------------------------------------------ 5. Abstract We propose to test a new method for identifying the spherical harmonic index of pulsation modes in variable white dwarfs, pre-white dwarfs, and central stars of planetary nebulae. Once the mode-indices are found for such stars, the observed periods can yield accurate measurements of mass, luminosity, rotation rate, magnetic field strength, and interior structure. Unfortunately, so far only a single star, PG1159-035, shows a pulsation spectrum rich enough for unambiguous identification of both ell=1 and ell=2 modes via its observed pattern of periods alone. Theory predicts that limb darkening should cause the amplitudes of ell=1 and 2 modes to vary differently with wavelength in the UV. However, previous UV observations directed at determining mode indices in DA white dwarfs show that the models must be calibrated before this method can prove truly useful. We therefore propose to measure amplitude versus wavelength for the 20 known ell=1 and 9 known ell=2 modes in PG1159-035 using the STIS FUV- MAMA. We will thus measure the limb-darkening law for pre- white dwarfs, calibrate models for future application to other post-AGB pulsators, and truly test a new observational tool of enormous potential. ------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 2] Observations Description ------------------------ We propose to observe PG1159-035 with the STIS FUV-MAMA detector, the G140L grating, and a 52 * 0.2 slit, in TIME-TAG mode for a total of 20 orbits, divided into seven 3-orbit visits and one 2-orbit visit, to obtain time- resolved spectrophotometry. According to the STIS exposure time calculator, we expect a peak local count rate of 13.27 counts/sec/pix at 1275 Angstrom. After acquiring the data, we will add them in 100 Angstrom and 40 sec bins for a sampling rate with high enough S/N to determine the amplitude of the pulsation modes and differentiate between different ell values. We would like to have the visits scheduled approximately a day apart to provide the necessary time coverage to separate modes in frequency. We will use the G140L grating, since its spectral region (in the UV) gives us greater sensitivity to both the relative amplitude of the pulsations and the temperature of the star. As a result, we will be better able to distinguish modes with different ell using the spectral region of this grating. We will use the 52 * 0.2 slit to get as much light as possible from the star with minimal complications arising from buffer overflow. Since the slit width is 0.2'', we request on-board target acquisition. We request seven visits, spread over approximately seven days, for PG1159-035. The beat periods of the pulsation modes vary from several hours to about a day. By observing it approximately once per day for a week, we can monitor several complete beat cycles of the closest spaced modes in its complex fourier pulsation spectrum, a critical requirement for differentiating modes of different ell. Fewer than twenty orbits within the same week would not give us sufficient time coverage to separate modes in the fourier transform of the light curve. Real Time Justification ----------------------- These observations are Time-Critical. We must observe PG1159-035 from the ground simultaneously with the HST to assure a good measurement of the optical amplitudes. We will therefore coordinate the observations with selected sites of the Whole Earth Telescope collaboration. Once we know the telescope time allocation on the ground, we will use the BETWEEN constraints to ensure simultaneous observations with the HST. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PG1159-035 STAR, PG1159 STAR, RA=12H 1M 45.98S +/- 0.3", DEC=- J2000 V = 14.49+/-0.36 PULSATING VARIABLE 03D 45' 40.6" +/- 0.3", PLATE- TYPE=PG1159 ID=03O9 E(B-V) = 0.0 F(1300)=11.3e-13 Coordinate Source: GUIDE_STAR_CATALOG Comments: F(1300) and E(B-V) from Dreizler & Heber, 1998 A&A 334, 618. Broadband V magnitude from GSC Catalog. No emission lines observed in previous UV observations (e.g. Kruk & Werner, 1998 ApJ 502, 858). 9159( 5) - 09/14/01 10:51 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 09-May-2002:00:00:01.0 AND 10-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 5] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 10-May-2002:00:00:01.0 AND 11-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 6] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 11-May-2002:00:00:01.0 AND 12-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 7] Visit: 04 Visit Priority: Visit Requirements: BETWEEN 12-May-2002:00:00:01.0 AND 13-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 8] Visit: 05 Visit Priority: Visit Requirements: BETWEEN 13-May-2002:00:00:01.0 AND 14-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 9] Visit: 06 Visit Priority: Visit Requirements: BETWEEN 14-May-2002:00:00:01.0 AND 15-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 10] Visit: 07 Visit Priority: Visit Requirements: BETWEEN 15-May-2002:00:00:01.0 AND 16-May-2002:00:00:01.0 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 PG1159-035 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1.0 S SEQ 10-20 NON-INT CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 36 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 30 PG1159-035 STIS/F TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=100 1 44 M NO SPLIT UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 9159( 5) - 09/14/01 10:51 - [ 11] Summary Form for Proposal 9159 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BUFFER-TIME=100 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 09-May-2002 00 00 01.0 AND 10-May-2002 00 00 01.0 SEQ 10-20 NON-INT NO SPLIT BETWEEN 10-May-2002 00 00 01.0 AND 11-May-2002 00 00 01.0 BETWEEN 11-May-2002 00 00 01.0 AND 12-May-2002 00 00 01.0 BETWEEN 12-May-2002 00 00 01.0 AND 13-May-2002 00 00 01.0 BETWEEN 13-May-2002 00 00 01.0 AND 14-May-2002 00 00 01.0 BETWEEN 14-May-2002 00 00 01.0 AND 15-May-2002 00 00 01.0 BETWEEN 15-May-2002 00 00 01.0 AND 16-May-2002 00 00 01.0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names PG1159-035 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------