! File: 3513C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:10:26:52 coverpage: title_1: NON-LTE ANALYSIS OF THE POPULATION II POST-AGB STARS ROB 162 AND title_2: K648 sci_cat: STELLAR ASTROPHYSICS sci_subcat: LATE EVOLUTION proposal_for: GO pi_fname: ULRICH pi_lname: HEBER pi_inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL pi_country: GERMANY pi_phone: 49-431-8804104 hours_pri: 3.20 num_pri: 2 hrs: Y off_fname: VOLKER off_lname: WEIDEMANN off_title: PROFESSOR off_inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL off_addr_1: OLSHAUSENSTR. 40 off_city: D2300 KIEL off_country: F.R.G. off_phone: +49 431 8804104 ! end of coverpage abstract: line_1: Post-AGB stars in galactic globular clusters are Rosetta stones for our line_2: understanding of late phase of stellar evolution of low mass stars. They are line_3: also important objects to study the early phases of the chemical evolution of line_4: our galaxy because they are amongst very few cluster stars for which the helium line_5: abundance can be determined directly. line_6: ROB 162 (in NGC 6397) and K 648, the central star of a PN in M 15, are two line_7: post-AGB stars in very metal poor clusters. Quantitative optical spectroscopy line_8: indicated that these two stars have a very different evolutionary history with line_9: respect to dredge-up events of nuclear processed matter. K 648 is strongly line_10: enriched in carbon indicating strong dredge-up from interior layers of the line_11: progenitor star. ROB 162, on the other hand, does not show any indication for line_12: dredge-up from optical spectroscopy. line_13: It is proposed to determine C, N and O abundances from UV-spectroscopy with the line_14: FOS using appropriate NLTE model atmospheres developed by our group. These line_15: cannot be derived from optical spectra and will put important constraints on the line_16: dredge-up history of the two stars. In the case of K 648, it gives the unique line_17: possibility to study different layers of the progenitor star, since we can line_18: compare the photospheric abundance to that of the Planetary Nebula. In the case line_19: of ROB 162, these abundances can prove or disprove the absence of dredge-up. line_20: If proven, a direct determination the primordial helium abundance results. ! ! end of abstract general_form_proposers: lname: HEBER fname: ULRICH title: PI inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL country: F.R.G. esa: Y ! lname: DREIZLER fname: STEFAN inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL country: F.R.G. esa: Y ! lname: RAUCH fname: THOMAS inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL country: F.R.G. esa: Y ! lname: WERNER fname: KLAUS inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL country: F.R.G. esa: Y ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The original proposal applied for GHRS observations (G140L) line_2: of two post-AGB stars of population II. Due to the failure line_3: of side 1 we changed 3 of the 4 proposed observations to the line_4: FOS. line_5: The spacecraft time awarded to the project is insufficient line_6: in order to complete it. We have decided to observe only one line_7: target, K648, because of its scientific merits. Moreover, line_8: we want to restrict the observations to some strategic line_9: lines of NIII, NIV, CIII, CIV, and OIV which lie in the line_10: range 1225 to 1255 Angstroem and 1320 to 1355 Angstroem. line_11: The measurement of these lines can be achieved by two line_12: spectra taken with the GHRS and grating G160M. This has the line_13: advantage over the FOS that it results in spectra line_14: of higher resolution than the FOS. The full spectral line_15: resolution of G160M will not be necessary and we will bin line_16: the data afterwards as appropriate. We aim at a S/N of 20 line_17: for the unbinned data. This way is more flexible than the line_18: FOS option since it allows an optimum trade-off between line_19: S/N and spectral resolution for the spectral analysis by line_20: NLTE-model atmospheres. line_21: K648 has been observed with HST with PC (GTO proposal No. line_22: 1046 in cycle 0). This image will allow to measure line_23: coordinates for the target as well as for a suitable offset ! question: 4 section: 1 line_1: High resolution optical spectra of ROB 162 have been obtained with the line_2: ESO CASPEC spectrograph at the 3.6m telescope and were analysed by means line_3: of Non-LTE model atmospheres techniques. Recently, three additonal CASPEC line_4: spectra have been obtained, which yield a S/N near 100. These spectra line_5: are still under investigation and will allow to improve on the results line_6: of Heber and Kudritzki (1986). However, even these spectra do not show line_7: any traces of metal lines. Metal lines can only be measured in the UV. line_8: Optical spectra of K648 (of about 0.1nm resolution) have been obtained at the line_9: Calar Alto observatory using the Cassegrain Twin spectrograph at the 3.5m line_10: telescope. These spectra were taken with a very small slit under superb line_11: seeing conditions, which is a prerequisite since K 648 is located in a line_12: very crowded field close to the center of M15. In addition K648 is line_13: surrounded by a compact planetary nebula and photospheric Balmer absorptions line_14: have for the first time been resolved from the intense nebular Balmer line_15: emission as detailed in section 1. These spectra also allow to measure line_16: He II, C III and C IV absorption lines with high precision, which will line_17: allow the atmospheric parameters and the carbon abundance to be line_18: determined from appropriate NLTE model atmospheres. Abundances of other line_19: metals can only be obtained from ultraviolet spectra. line_21: Ultraviolet spectroscopy of K648 and ROB 162 has been carried out with line_22: the IUE satellite. Both stars have been observed in the low resolution line_23: mode (about 0.5nm). These spectra have been used to estimate the ! question: 5 section: 1 line_1: ! question: 7 section: 1 line_1: Data reduction of FOS spectra will be carried out with using IRAF + STSDAS line_2: which is presently installed on the MODCOMP computer of the Physics department line_3: in Kiel. line_4: Observed line profiles will be compared to theoretical predictions in order line_5: to derive atmospheric parameters and abundances. To this end, the model line_6: atmosphere calculations described in section 1 will be extended. Numerical line_7: calculations will be carried out using the Cray X-MP 216 computer of the line_8: Rechenzentrum der Universitaet Kiel. ! question: 8 section: 1 line_1: ! question: 9 section: 1 line_1: a. List HST program numbers and titles, and specify whether they are related line_2: to this project or not. line_4: ID 2741: Non-LTE spectral analysis of the pre white dwarf PG1159-035 line_5: not related to this project line_10: b. Summarize the main results obtained from previous related programs. line_12: the observations are scheduled for cycle 1, in the long range schedule line_13: as of February, line_16: c. List publications resulting from the above data (Format: Title, line_17: Authors,Journal, Volume, Page, and Year.) ! question: 10 section: 1 line_1: Computer resources: line_2: i) VAX 8550 of the Rechenzentrum der Universitaet Kiel, line_3: MODCOMP computer of the physics department; 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 Non-LTE model atmosphere calculations. line_8: Research assistance: Dipl. Ing. G. Jonas (data reduction specialist). line_9: One graduate student will assist the proposers in the spectral line_10: analysis. ! !end of general form text general_form_address: lname: HEBER fname: ULRICH category: PI inst: INSTITUT F. THEOR. PHYSIK U. STERNWARTE DER UNI. KIEL addr_1: OLSHAUSENSTR. 40 city: KIEL country: F.R.G. phone: +49 4318804103 telex: 292706 IAPKI D ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: K648 descr_1: A,108,184 pos_1: RA=21H 29M 59.4175S +/- 0.02S, pos_2: DEC=+12D 10' 25.987" +/- 0.3", pos_3: PLATE-ID=02V2 equinox: 2000 pos_epoch_bj: J fluxnum_1: 1 fluxval_1: V = 14.95 +/- 0.2, TYPE=DOZ, E(B-V)=0.08 fluxnum_2: 2 fluxval_2: F-CONT(1300) = 2.25E-13 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: K648 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 30.6S fluxnum_1: 2 priority: 1 param_1: SEARCH-SIZE=5, param_2: BRIGHT=RETURN, param_3: LOCATE=YES, param_4: MAP=END-POINT req_1: CYCLE 2; req_2: ONBOARD ACQ FOR 1.100 comment_1: STEP TIME = 0.2S ! linenum: 1.100 targname: K648 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 2 priority: 1 req_1: CYCLE 2; req_2: ONBOARD ACQ FOR 2.000-3.000; comment_1: STEP TIME = 0.2S ! linenum: 2.000 targname: K648 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G160M wavelength: 1225-1258 num_exp: 2 time_per_exp: 34M s_to_n: 20 fluxnum_1: 2 priority: 1 param_1: FP-SPLIT=FOUR req_1: CYCLE 2 ! linenum: 3.000 targname: K648 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G160M wavelength: 1317-1350 num_exp: 2 time_per_exp: 32.1M s_to_n: 20 fluxnum_1: 2 priority: 1 param_1: FP-SPLIT=FOUR req_1: CYCLE 2 ! ! end of exposure logsheet ! No scan data records found