! File: 2741C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:10:49:41 coverpage: title_1: NLTE SPECTRAL ANALYSIS OF THE PRE WHITE DWARF PG1159-035 sci_cat: STELLAR ASTROPHYSICS proposal_for: GO pi_title: PROF. pi_fname: K. pi_lname: HUNGER pi_inst: KIEL UNIVERSITY pi_country: FRG pi_phone: 431-880-4110 keywords_1: STARS: WHITE DWARFS; NON-LTE ANALYSIS hours_pri: 2.25 num_pri: 1 hrs: X pi_position: DIRECTOR off_fname: K. off_lname: HUNGER off_title: DIRECTOR off_inst: INSTITUT F. THEOR. PHYSIK U. STERNW. off_addr_1: OLSHAUSENSTR. 40 off_city: KIEL off_state: S-H off_zip: D 300 off_country: FRG ! end of coverpage abstract: line_1: PG1159-035 is the prototype of a new class of hydrogen-deficient pre white line_2: dwarfs (PWD) representing the hottest episode (Teff.GE.100,000K) of line_3: PWD-evolution. It also shows low-amplitude multi-periodic variations which line_4: have been identified as non-radial g-mode pulsations. Because of these line_5: properties, PG1159-035 is a rosetta stone for our understanding of the late line_6: phase of stellar evolution. Modelling of the pulsations not only allows the line_7: stellar mass to be determind but also the internal structure to be probed. line_8: However, the position of PG1159-035 in the HR diagram and its chemical surface line_9: composition are a prerequisite for the pulsational models as well as for the line_10: discussion of its evolutionary status. Due to the lack of adequate model line_11: atmospheres, these basic atmospheric parameters have not yet been determined. line_12: To construct such models is a challenging problem because non-LTE effects are line_13: large and a very peculiar composition (He-, C- and O-rich) has to be accounted line_14: for. Since available model atmosphere techniques fail, we have developed a new line_15: computer code based on operator perturbation techniques which gave way to a new line_16: generation of highly sophisticated non-LTE model atmospheres. Proposed HST line_17: spectroscopy of crucial UV lines will allow the basic atmospheric parameters to line_18: be determined with high precision. These will set important constraints to be line_19: met by pulsational and evolutionary models. ! ! end of abstract general_form_proposers: lname: HUNGER fname: K. title: P.I. inst: KIEL UNIVERSITY country: FRG esa: X ! lname: HEBER fname: U. inst: KIEL UNIVERSITY country: FRG esa: X ! lname: RAUCH fname: TH. inst: KIEL UNIVERSITY country: FRG esa: X ! lname: WERNER fname: K. inst: KIEL UNIVERSITY country: FRG esa: X ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The ST High Resolution Spectrograph (HRS) shall be used to obtain ultraviolet line_2: spectroscopy of PG1159-035. Scientific spectra to be obtained with the HRS line_3: (large science aperture, LSA, 2*2 arcsec.) are as follows: line_4: i) Low resolution spectrum (grating G140L) in the wavelength range 115 nm - line_5: 143.6 nm in order to observe the NV resonance doublet at 124 nm. (optimum) S/N line_6: = 60 is aimed at. Low resolution (R = 2000) suffices since IUE high resolution line_7: spectra show the lines to be relatively strong and unblended. line_8: ii) Medium resolution spectrum (grating G160M) in the wavelength range line_9: 135.3 nm to 138.6 nm in order to measure the crucial OV, 137.1 nm line. S/N = 30 line_10: is aimed at. Medium resolution (R = 20000) is required since IUE high line_11: dispersion spectra indicate that the line is weak. Proper continuum placement line_12: will be assured from the low resolution spectrum (i). line_13: iii) Medium resolution spectrum (grating G160M) in the wavelength range line_14: 153.3 nm to 156.6 nm in order to measure the profile of the CIV resonance line_15: doublet at 155 nm. S/N = 30 is aimed at. Medium resolution (R = 20000) is line_16: required because the photospheric lines are blended with interstellar line_17: components. Proper continuum placement will be assured from summed low line_18: resolution spectra, which will become available during GTO-program No. 1148. line_19: It is intended to utilize these spectra when officially released to the public. ! question: 4 section: 1 line_1: Optical spectra of high S/N ratio (near 100) have been obtained at ESO, 3.6 m line_2: telescope and at DSAZ-3.5 m telescope, covering the wavelength range 400 nm to line_3: 700 nm at a spectral resolution of 0.3 nm. These spectra have been used for an line_4: exploratory NLTE analysis (see Sect. 2 and Werner et al., 1988). line_5: Well exposed low resolution IUE spectra (optained with the SWP and LWR line_6: cameras) required 15 min and 30 min of exposure time, respectively. However, line_7: extremely long high-resolution IUE spectrum (1020 min) allowed crucial lines line_8: to be detected. However, S/N is too low for a quantitative analysis. line_9: Therefore, the UV lines of crucial importance for the analysis (see Sect. 2) line_10: can only be observed with HST/HRS. ! question: 5 section: 1 line_1: 1 Object (PG1159-035) shall be observed with the HRS (3 images). Blind line_2: acquisition appears to be possible since the stars lies in an uncrowded field line_3: and will have been observed with HST/HRS before the proposed observations (GTO line_4: proposal No. 1148). line_5: Exposure times can be estimated from absolutely calibrated UV fluxes (IUE) and line_6: the HRS efficiency (Duncan and Turnshek, 1988, STScI-Newsletter, Vol. 5, line_7: No 3). These values are listed below: line_9: Wavelength S/N grating S-lambda F-lambda (erg/ t line_10: (nm) (flux) cm/cm/s/0.1nm) (min.) line_12: 137 30 G160M 5.6E11 9.4E-13 28 line_13: 155 30 G160M 8.2E11 5.5E-13 33 line_14: 124 60 G140L 1.18E13 1.3E-12 4 ! question: 7 section: 1 line_1: Data reduction of HRS spectra will be carried out using procedures implemented line_2: in the MIDAS package of the European Coordinated Facility (Garching), which line_3: will be installed on the VAX 8550 of the "Rechenzentrum der Universitaet Kiel". line_4: Observed profiles will be compared to theoretical predictions in order to line_5: derive Teff, log g and abundances. To this end, the model atmosphere line_6: calculations described in sect. 2 will be extended. Numerical calculations will line_7: be carried out using the Cray X-MP 216 computer of the "Rechenzentrum der line_8: Universitaet Kiel". ! question: 8 section: 1 line_1: No special requests. line_3: References: line_4: Auer, L.H., Mihalas, D.: 1969, Astrophys. J. 158, 641 line_5: Fontaine, G., Wesemael, F.: 1987, IAU coll. No. 95, 319 line_6: Heber, U., Hunger, K.: 1987, IAU coll. No. 95, 599 line_7: Heber, U., Hunger, K., Rauch, T., Werner, K.: 1987, IAU Symp. 132, 117 line_8: Heber, U., Hunger, K., Werner, K.: 1987, IAU Symp. No. 132, 389 line_9: Heber, U., Werner, K., Drilling, J.S.:1988, Astron. Astrophys. 194, 223 line_10: Kawaler, S.D.: 1987, IAU coll. No. 95, 297 line_11: Liebert, J.W.: 1988, IAU Symp. No. 131, in press line_12: Rauch, T., Werner, K.: 1988, Astron. Astrophys. 202, 159 line_13: Sahal-Brechot, S., Segre, E.R.A.: 1971, Astron. Astrophys. 13, 161 line_14: Starrfield, S.: 1987, IAU coll. No. 95, 309 line_15: Vidal, C.R., Cooper, J., Smith, E.W.: 1969, Phys. Rev. 185, 140 line_16: Werner, K.: 1987, in "Numerical Radiative Transfer", Cambridge Univ. Press p. 67 line_17: Werner, K.: 1988, Astron. Astrophys. 204, 159 line_18: Werner, K., Heber, U., Hunger, K.: 1988, IAU coll. No. 114 in press line_19: Winget, D., Kepler, S.O., Robinson, E., Nather, R.E., O'Donoghue, D.: 1985, line_20: Ap. J. 292, 606 ! question: 10 section: 1 line_1: Computer resources: line_2: i) VAX 8550 of the "Rechenzentrum der Universitaet Kiel"; line_3: MODCOMP CLASSIC of the "Physikzentrum der Universitaet Kiel"; line_4: to be used for data reduction. line_5: ii) CRAY X-MP 216 of the "Rechenzentrum der Universitaet Kiel" line_6: to be used for NLTE model atmosphere calculations. line_8: Research assistance: Dipl. Ing. G. Jonas (data reduction specialist) . line_9: Two graduate students will assist the proposers in the spectral analysis. ! !end of general form text general_form_address: lname: HUNGER fname: K. title: PROF. category: PI inst: KIEL UNIVERSITY addr_1: INSTITUT F. THEOR. PHYSIK addr_2: OLSHAUSENSTRASSE 40 city: KIEL D-2300 country: F.R. GERMANY ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: GW-VIR name_2: PG1159-035 descr_1: STAR; TYPE=DOZ PRE-WHITE-DWARF pos_1: RA = 12H 1M 45.981S +/- 0.013S, pos_2: DEC = -3D 45' 40.74" +/- 0.2", pos_3: PLATE-ID=0309 equinox: 2000 pos_epoch_bj: J fluxnum_1: 1 fluxval_1: V = 14.87 +/- 0.2, TYPE=DOZ, E(B-V)=0.00 fluxnum_2: 2 fluxval_2: F-CONT(1370) = 9.4 +/- 1.0 E-13 fluxnum_3: 3 fluxval_3: F-CONT(1550) = 5.5 +/- 0.6 E-13 fluxnum_4: 4 fluxval_4: F-CONT(1240) = 1.3 +/- 0.1 E-12 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: GW-VIR config: FOS/BL opmode: ACQ/BINARY aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 0.66S priority: 1 param_1: FAINT=780,BRIGHT=39000 req_1: CYCLE 1; req_2: ONBOARD ACQ FOR 1.100 ! linenum: 1.100 targname: GW-VIR config: FOS/BL opmode: ACQ/PEAK aperture: 0.25X2.0 sp_element: MIRROR num_exp: 1 time_per_exp: 3S priority: 1 param_1: TYPE=UP req_1: CYCLE 1; req_2: SPATIAL SCAN ; req_3: ONBOARD ACQ FOR 2. ! linenum: 2.000 targname: GW-VIR config: FOS/BL opmode: ACCUM aperture: 0.25X2.0 sp_element: G130H wavelength: 1200-1600 num_exp: 1 time_per_exp: 103M s_to_n: 120 fluxnum_1: 4 priority: 1 req_1: CYCLE 1 ! ! end of exposure logsheet scan_data: line_list: 1.1 fgs_scan: cont_dwell: D dwell_pnts: 11 dwell_secs: 0.00 scan_width: 0.0000 scan_length: 0.5500 sides_angle: 0.0000 number_lines: 1 scan_rate: 0.0000 first_line_pa: 90.0000 scan_frame: S/C len_offset: 0.225 wid_offset: 0. ! ! end of scan data