! File: 3798C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:19:51:58 coverpage: title_1: A SEARCH FOR RADIAL PULSATIONS IN WHITE DWARFS sci_cat: STELLAR ASTROPHYSICS sci_subcat: PULSATING STARS proposal_for: GO pi_fname: STEVEN pi_mi: D. pi_lname: KAWALER pi_inst: IOWA STATE UNIVERSITY pi_country: USA pi_phone: 515-294-9728 hours_pri: 1.50 num_pri: 3 hsp: Y funds_amount: 88685 funds_length: 12 off_fname: RICHARD off_mi: E. off_lname: HASBROOK off_title: CONTR & GRANTS OFF off_inst: IOWA STATE UNIVERSITY off_addr_1: 209 BEARDSHEAR off_addr_2: IOWA STATE UNIVERSITY off_city: AMES off_state: IA off_zip: 50011 off_country: USA off_phone: 515-294-5225 ! end of coverpage abstract: line_1: Several classes of NONRADIALLY pulsating white dwarfs are known, with line_2: pulsation periods of several minutes. Theoretical work predicts that line_3: DB and DA white dwarfs that are slightly hotter than the known line_4: nonradial instability strips should be unstable to RADIAL pulsations line_5: with periods of about 0.1--1 second. However, ground-based line_6: observations have failed to reveal such periodicities. We propose to line_7: use HST's High Speed Photometer to search for the predicted radial line_8: pulsations in DB and DA white dwarfs. UV high-speed photometry offers line_9: the advantages of larger stellar fluxes (the effective temperatures of line_10: our three targets are 13,000--30,000 K) and significantly larger line_11: pulsation amplitudes (factors of 2 to 3) compared to ground-based line_12: photometry, along with freedom from atmospheric scintillation, giving line_13: HST a distinct gain over any ground-based facility. The presence line_14: (or absence) of the predicted rapid oscillations will provide line_15: significant new information for (or challenges to) the theory of line_16: white-dwarf pulsations, structure, and evolution. ! ! end of abstract general_form_proposers: lname: KAWALER fname: STEVEN title: PI mi: D. inst: IOWA STATE UNIVERSITY country: USA ! lname: BOND fname: HOWARD mi: E. inst: SPACE TELESCOPE SCIENCE INSTITUTE country: USA ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: Scientific Justification. ! question: 3 section: 1 line_1: Short Description of Observations. line_2: We will obtain high-speed photometry of white dwarfs with the HSP. line_3: Since the predicted periods lie in the range 0.1-10 sec, we will use line_4: a time resolution of 0.01 sec. The observing runs on each target line_5: will be 30 min long. line_6: To maximize the count rates, we will use the F140LP filter with the line_7: largest available aperture (the 10" acquisition aperture). ! question: 4 section: 1 line_1: Justify need for HST. line_2: The principal advantages of performing this investigation with HST line_3: arise from its UV capabilities and the lack of scintillation noise line_4: in observations from space. For integration times of 0.05 second, line_5: r.m.s. intensity fluctuations from scintillation are about 1 percent in line_6: a 4-m telescope. The lack of scintillation noise with ST therefore line_7: pushes the amplitude limit well below that available to ground-based line_8: instruments. The two primary candidate targets are white dwarfs that are line_9: much brighter in UV than in optical wavelengths. In the F140LP line_10: configuration a 25,000K blackbody radiates roughly 60 times more energy line_11: per second than in the V band, and 6.5 times more than between 4000 to line_12: 7000 A. In addition, for radial pulsations the amplitude of variation line_13: in luminosity for a given temperature perturbation scales with the line_14: frequency. Therefore, variations in the optical flux of 0.0005 mag line_15: correspond to UV variations of 0.001 mag. Over the same total run line_16: length upper limits in the UV amplitude correspond to limits 2 times line_17: smaller than achieved by Robinson (1984) in the optical. Thus HST is line_18: the best instrument to search for radial pulsations in DB (and DA) line_19: white dwarfs. No searches for radial pulsations in DB white dwarfs have line_20: been made. Optical searches for radial pulsations in DA white dwarfs line_21: are summarized by Robinson (1984). An optical 4-m telescope cannot line_22: reach the same amplitude limit as HST can in the UV. ! question: 5 section: 1 line_1: Justification for realtime data or special scheduling. line_2: (none) ! question: 6 section: 1 line_1: Justify special calibrations, use of dark time, or ininterrupted line_2: exposures. line_3: Since we will be looking for low-amplitude multiperiodic line_4: signals in the data, we require uninterrupted 30 minute exposures with line_5: short integration times. Any interruptions in the data will introduce line_6: complex alias structure that would severely hamper our ability to detect line_7: the expected weak signals. ! question: 7 section: 1 line_1: Plans for data reduction. line_2: Analysis of the time-series data will consist of Fourier analysis and line_3: power spectrum analysis in a search for power at the relevant line_4: frequencies. In the best case, the data from the HSP would be line_5: transformed directly. However, the pointing jitter coupled with the line_6: expanded PSF introduce excess power at frequencies below 0.6 Hz and line_7: complicate any search for longer period modes. While Nelson et al. line_8: (1991) show that the system is capable of millimagnitude precision at line_9: higher frequencies, we still will need to attempt to compensate for the line_10: jitter using knowledge of the PSF and the detailed pointing history line_11: available in the engineering data stream. line_12: We will then use the measured frequencies in a detailed comparison with line_13: theoretical models. This effort will involve computation of a grid of line_14: models with the parameters relevant to the observed stars, and line_15: computation of the periods and growth rates. ! question: 8 section: 1 line_1: Additional comments. line_2: (none) ! question: 9 section: 1 line_1: Have you received previous HST observing time? line_2: Co-I Bond is PI for program 2570 ("Recent Mass Ejection from line_3: Planetary-Nebula Nuclei") and is a Co-I for program 2593 ("White line_4: Dwarfs"). A portion of the data for program 2570 was obtained on line_5: August 6, 1991, just before the Phase 1 proposal was written. ! question: 10 section: 1 line_1: Resources to be supplied by your institutions. line_2: The home institutions of the P.I. and Co. I. will provide computing line_3: facilities, administrative support, and secretarial assistance in line_4: support of this investigation. ! !end of general form text general_form_address: lname: KAWALER fname: STEVEN mi: D. category: PI inst: IOWA STATE UNIVERSITY addr_1: DEPARTMENT OF PHYSICS AND ASTRONOMY addr_2: IOWA STATE UNIVERSITY city: AMES state: IA zip: 50011 country: USA phone: 515-294-9728 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: PG0112+104 name_2: GR409 descr_1: A,119 pos_1: RA = 01H 14M 37.68S +/- 0.33", pos_2: DEC = +10D 41' 5.31" +/- 0.33", pos_3: PLATE-ID=00GR equinox: J2000 pm_or_par: Y pos_epoch_bj: B pos_epoch_yr: 1982.80 ra_pm_val: -0.002400 dec_pm_val: -0.0420 fluxnum_1: 1 fluxval_1: V=15.4 fluxnum_2: 1 fluxval_2: TYPE=DB2 fluxnum_3: 2 fluxval_3: B-V=-0.40 ! targnum: 2 name_1: GD358 name_2: EG239 name_3: GSC2582-23 descr_1: A,119,175 pos_1: RA = 16H 47M 18.64S +/- 0.33", pos_2: DEC = 32D 28' 32.5" +/- 0.33", pos_3: PLATE-ID=0380 equinox: J2000 pm_or_par: Y pos_epoch_bj: B pos_epoch_yr: 1983.29 ra_pm_val: -0.013067 dec_pm_val: 0.0290 fluxnum_1: 1 fluxval_1: V=13.65 fluxnum_2: 1 fluxval_2: TYPE=DB2 fluxnum_3: 2 fluxval_3: B-V=-0.11 fluxnum_4: 2 fluxval_4: U-B=-1.04 ! targnum: 3 name_1: G130-5 name_2: GSC2771-733 descr_1: A,120 pos_1: RA = 23H 43M 51.09S +/- 0.33", pos_2: DEC = +32D 32' 48.2" +/- 0.33", pos_3: PLATE-ID=01H1 equinox: J2000 pm_or_par: Y pos_epoch_bj: B pos_epoch_yr: 1982.80 ra_pm_val: -0.016000 dec_pm_val: -0.0600 fluxnum_1: 1 fluxval_1: V=12.92 fluxnum_2: 1 fluxval_2: TYPE=DA4 fluxnum_3: 2 fluxval_3: B-V=0.14 fluxnum_4: 2 fluxval_4: U-B=-0.61 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: PG0112+104 config: HSP/UV2 opmode: ACQ num_exp: 1 time_per_exp: 2.0M s_to_n: 12 fluxnum_1: 1 priority: 1 param_1: DATA-FORMAT=WORD req_1: ONBOARD ACQ FOR 2; req_2: PCS MODE F; req_3: CYCLE 2 ! linenum: 2.000 targname: PG0112+104 config: HSP/UV2 opmode: SINGLE aperture: 10.0 sp_element: F140LP num_exp: 1 time_per_exp: 30M fluxnum_1: 1 priority: 1 param_1: SAMPLE-TIME=0.01, param_2: PRECISION=HIGH req_1: PCS MODE F; req_2: NON-INT; req_3: CYCLE 2 comment_1: OBSERVATION IS VERY SENSITIVE TO comment_2: JITTER; SHOULD BE SCHEDULED TO AVOID comment_3: DAY-NIGHT TRANSITIONS IF POSSIBLE; OR comment_4: TRANSITIONS SHOULD BE AT BEGINNING OR comment_5: END OF EXPOSURE. ! linenum: 2.500 targname: DARK config: S/C opmode: DATA aperture: NONE num_exp: 1 time_per_exp: 1S priority: 1 param_1: FORMAT=FN req_1: PAR WITH 2; req_2: CRIT OBS; req_3: CYCLE 2 comment_1: THE FN FORMAT IS SPECIFIED IN ORDER TO comment_2: ASSURE THAT THE ENGINEERING DATA ARE comment_3: RECORDED AT 32 KBPS, FOR SUBSEQUENT comment_4: ATTEMPTS TO REMOVE GUIDING JITTER FROM comment_5: THE HSP PHOTOMETRY ! linenum: 3.000 targname: GD358 config: HSP/UV2 opmode: ACQ num_exp: 1 time_per_exp: 0.5M s_to_n: 14 fluxnum_1: 1 priority: 1 param_1: DATA-FORMAT=WORD req_1: ONBOARD ACQ FOR 4; req_2: PCS MODE F; req_3: CYCLE 2 ! linenum: 4.000 targname: GD358 config: HSP/UV2 opmode: SINGLE aperture: 10.0 sp_element: F140LP num_exp: 1 time_per_exp: 30M fluxnum_1: 1 priority: 1 param_1: SAMPLE-TIME=0.01, param_2: PRECISION=HIGH req_1: PCS MODE F; req_2: NON-INT; req_3: CYCLE 2 comment_1: OBSERVATION IS VERY SENSITIVE TO comment_2: JITTER; SHOULD BE SCHEDULED TO AVOID comment_3: DAY-NIGHT TRANSITIONS IF POSSIBLE; OR comment_4: TRANSITIONS SHOULD BE AT BEGINNING OR comment_5: END OF EXPOSURE. ! linenum: 4.500 targname: DARK config: S/C opmode: DATA aperture: NONE num_exp: 1 time_per_exp: 1S priority: 1 param_1: FORMAT=FN req_1: PAR WITH 4; req_2: CRIT OBS; req_3: CYCLE 2 comment_1: THE FN FORMAT IS SPECIFIED IN ORDER TO comment_2: ASSURE THAT THE ENGINEERING DATA ARE comment_3: RECORDED AT 32 KBPS, FOR SUBSEQUENT comment_4: ATTEMPTS TO REMOVE GUIDING JITTER FROM comment_5: THE HSP PHOTOMETRY ! linenum: 5.000 targname: G130-5 config: HSP/UV2 opmode: ACQ num_exp: 1 time_per_exp: 1.0M s_to_n: 20 fluxnum_1: 1 priority: 1 param_1: DATA-FORMAT=WORD req_1: ONBOARD ACQ FOR 6; req_2: PCS MODE F; req_3: CYCLE 2 ! linenum: 6.000 targname: G130-5 config: HSP/UV2 opmode: SINGLE aperture: 10.0 sp_element: F140LP num_exp: 1 time_per_exp: 30M fluxnum_1: 1 priority: 1 param_1: SAMPLE-TIME=0.01, param_2: PRECISION=HIGH req_1: PCS MODE F; req_2: NON-INT; req_3: CYCLE 2 comment_1: OBSERVATION IS VERY SENSITIVE TO comment_2: JITTER; SHOULD BE SCHEDULED TO AVOID comment_3: DAY-NIGHT TRANSITIONS IF POSSIBLE; OR comment_4: TRANSITIONS SHOULD BE AT BEGINNING OR comment_5: END OF EXPOSURE. ! linenum: 6.500 targname: DARK config: S/C opmode: DATA aperture: NONE num_exp: 1 time_per_exp: 1S priority: 1 param_1: FORMAT=FN req_1: PAR WITH 6; req_2: CRIT OBS; req_3: CYCLE 2 comment_1: THE FN FORMAT IS SPECIFIED IN ORDER TO comment_2: ASSURE THAT THE ENGINEERING DATA ARE comment_3: RECORDED AT 32 KBPS, FOR SUBSEQUENT comment_4: ATTEMPTS TO REMOVE GUIDING JITTER FROM comment_5: THE HSP PHOTOMETRY ! ! end of exposure logsheet ! No scan data records found