! Proposal 6727, submission 1 ! PI: Donald E. Winget ! Received Fri Feb 2 13:12:38 EST 1996 ! From: nitta@bullwinkle.as.utexas.edu ! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /slash/RPS2/gd358_phase2/6727.prop ! Generated by PREPROCESSOR, version 6.0e ! Date: Fri Feb 2 11:43:31 CST 1996 Proposal_Information Title: A Unique Test of Asteroseismology: the DBV GD358 Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_Name: Donald E. Winget PI_Institution: University of Texas CoI_Name: S.O. Kepler CoI_Institution: Universidade Federal do Rio Grande do Sul Contact: Abstract: An improved understanding of the white dwarf stars has a great potential in both physics and astronomy. Determination of the basic physical parameters of the white dwarf stars will help us realize that potential; asteroseismology is the key. We can use asteroseismology to constrain the stellar structure and evolution, including the stellar mass and even the stellar distance if we can determine the pulsation indices (k,\ell,m) of the non-radial g-mode light variations observed in compact pulsators. We made tentative identifications for GD 358 using a method based on the frequency distribution of consecutive radial overtone g-modes. A comparison of the amplitude of the pulsation between the optical and the UV proves to be another independent method to identify the pulsation indices. Our project is to apply both methods to GD358. For the HST observations we will use the FOS blue digicon with the G160L grating in RAPID readout mode to obtain time-resolved spectrophotometry to measure the ultraviolet amplitudes. We will measure the optical amplitude with time series photometry. By observing the DBV star GD 358 with the HST, we have a unique opportunity to cross-calibrate the two methods - -- essential if we are to have confidence in the conclusions drawn from either method. The future of asteroseismology of white dwarf stars hinges on these observations; they will not be possible after Feb 97, with the replacement of FOS. Questions Observing_Description: We will use the FOS with the blue Digicon and the G160L grating in RAPID readout mode and the 1 arcsec upper aperture to obtain time resolved spectrophotometry with a sampling interval of 10 sec over the spectral region 1150 Angstrom to 2510 Angstrom. We will observe GD358 for 7 consecutive orbits of HST, which allows the accuracy we need to differentiate between A_1400A/A_5500A = 2.1 for l=1 and A_1400A/A_5500A = 2.5 for l=2. Further, we will be able to distinguish between l=1and l=2 geometries in the large amplitude LCFs at the 3-4 Sigma level. The centering will be done with a 4 stage peak-up procedure ensuring 0.04 arcsec centering accuracy on the target, necessary for S/N> 30. We have chosen the G160L grating because we wish to measure the amplitude of pulsation at shortest wavelength possible, were the dependence on l is strong, but also the widest coverage possible because the changes we will measure are continuum variations. The same setup was used on proposals G0-5581 and G0-6011, with success. The beat periods between the pulsations we will study are 2-4 hours, and hence will be well sampled in the 7 orbits. Note since the central (m=0) components strongly dominate each multiplet, we need not resolve the fine structure with the HST observations. Real_Time_Justification: We will observe GD358 with photoelectric photometry at McDonald Observatory contemporaneously with the HST observations to assure a good measurement of the optical amplitudes. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: V777HER Alternate_Names: WD1645+325,GD358 Description: STAR,DB, Position: RA=16H 47M 18.64S +/- 0.3",DEC=32D 28' 32.32" +/- 0.3",PLATE-ID=0380 Equinox: J2000 RV_or_Z: RA_PM: -0.01156 Dec_PM: 0.038 Epoch: B1983.2919921875 Annual_Parallax: 0.0273 Flux: V = 13.65 B = 13.54 B-V = -0.11 U-B = -1.04 TYPE=DBV Comments: The coordinates were obtained using the DSS. The proper motion and parallax were obtained from The General Catalogue of Trigonometric Stellar Parallax (1991). Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: SCHEDULABILITY 40% BETWEEN 12-AUG-1996 AND 20-AUG-1996 On_Hold_Comments: Visit_Comments: Exposure_Number: 10 Target_Name: V777HER Config: FOS/BL Opmode: ACQ/PEAK Aperture: 4.3 Sp_Element: G270H Wavelength: Optional_Parameters: SCAN-STEP-Y=1.23,SEARCH-SIZE-Y=3,SEARCH-SIZE-X=1,TYPE=UP Number_of_Iterations: 1 Time_Per_Exposure: 1.0S Special_Requirements: ONBOARD ACQ FOR 20 Comments: Stage 1 of 4 Stage peakup. Exposure_Number: 20 Target_Name: V777HER Config: FOS/BL Opmode: ACQ/PEAK Aperture: 1.0-PAIR-A Sp_Element: G270H Wavelength: Optional_Parameters: SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2,TYPE=UP Number_of_Iterations: 1 Time_Per_Exposure: 1.0S Special_Requirements: ONBOARD ACQ FOR 30 Comments: Stage 2 of 4 Stage peakup. Exposure_Number: 30 Target_Name: V777HER Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5-PAIR-A Sp_Element: G270H Wavelength: Optional_Parameters: SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3,TYPE=UP Number_of_Iterations: 1 Time_Per_Exposure: 1.0S Special_Requirements: ONBOARD ACQ FOR 40 Comments: Stage 3 of 4 Stage peakup. Exposure_Number: 40 Target_Name: V777HER Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.25-PAIR-A Sp_Element: G270H Wavelength: Optional_Parameters: SCAN-STEP-X=0.110,SCAN-STEP-Y=0.110,sEARCH-SIZE-X=4,TYPE=UP,SEARCH-SIZE-Y=4 Number_of_Iterations: 1 Time_Per_Exposure: 2.6S Special_Requirements: ONBOARD ACQ FOR 50 Comments: Stage 4 (the last Stage) of 4 Stage peakup. Changed to P4 peakuP Exposure_Number: 50 Target_Name: V777HER Config: FOS/BL Opmode: RAPID Aperture: 1.0-PAIR-A Sp_Element: G160L Wavelength: Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 Number_of_Iterations: 6 Time_Per_Exposure: 2750S Special_Requirements: Comments: ! Exposure_Number: 60 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: ! ! Exposure_Number: 70 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: For some unknown reason to us, exposure time for this EXPOSURE 70 generates Feasibility Warning. !There is nothing we do different from EXPOSURE 60, 70 - 110. ! ! Exposure_Number: 80 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: ! ! Exposure_Number: 90 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: ! ! Exposure_Number: 100 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,READ-TIME=10.0,COMB=YES,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: ! ! Exposure_Number: 110 ! Target_Name: V777HER ! Config: FOS/BL ! Opmode: RAPID ! Aperture: 1.0-PAIR-A ! Sp_Element: G160L ! Wavelength: ! Optional_Parameters: STEP-PATT=SINGLE,COMB=YES,READ-TIME=10.0,SUB-STEP=4 !Number_of_Iterations: 1 ! Time_Per_Exposure: 2750S !Special_Requirements: ! Comments: Data_Distribution ! Defaults indicated; change if desired Medium: 8MM Blocking_Factor: 10 Ship_To: PI_Address Ship_Via: Recipient_Email: ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator