Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5322 Report Date: 18-Jul-95:17:09 Version: ********** Check-in Date: ********** 1.Proposal Title: ORIGIN OF THE ULTRAHIGH-IONISATION OVIII EMISSION LINES IN TWO EXCEP- TIONAL (PRE- )WHITE DWARFS: KPD0005+5106 AND RXJ2117+3412: CYCLE4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Sub Category WHITE DWARFS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Klaus Werner 5584 GERMANY +49 431 880410 ------------------------------------------------------------------------------------ 7. Abstract We propose GHRS observations of two exceptional (pre-) white dwarf stars that uniquely show prominent ultrahigh-ionisation lines of OVIII. The origin of these spectral features is completely unknown. Although the two stars represent the hottest objects within their spectral subclass, a photospheric origin of these emission features is clearly excluded. It is suspected that a corona can be responsible for this phenomenon, and we propose observations that can proof this hypothesis. The first object is KPD0005+5106, the hottest helium rich white dwarf known so far (Teff=120kK). It would be the first detection of a corona around a white dwarf. The spectral analysis of HST data will also help to remove discrepancies between observed C and N abundances and predictions of diffusion/radiative levitation theory. The second object is RXJ2117.1+3412, the hottest PG1159 type central star of a PN. HST observations of this non-radial pulsator will also constrain the edge of the GW Vir instability strip at the high- luminosity limit. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.83 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5322 PI: Klaus Werner Proposal Title: ORIGIN OF THE ULTRAHIGH-IONISATION OVIII EMISSION LINES IN TWO EXCEP- TIONAL (PRE- )WHITE DWARFS: KPD0005+5106 AND RXJ2117+3412: CYCLE4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Klaus Werner 5584 GERMANY X Stefan Dreizler 5578 GERMANY X Ulrich Heber 5578 GERMANY X Thomas Rauch 5584 GERMANY X Tom Fleming 1212 USA Ed Sion 3720 USA Gerard Vauclair 5474 FRANCE X ------------------------------------------------------------------------------------ 3. Description of proposed observations. The GHRS shall be used to perform high-resolution high-S/N UV specroscopy ow two extremely hot (pre-) white dwarf stars. For each star 4 wavelength ranges between 124nm and 300nm shall be recorded using the G160M and G270M gratings. These ranges cover the most important lines for our analysis. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Medium resolution optical spectra of KPD0005+5106 and RXJ2117.1+3412 were obtained with the TWIN spectrograph at the 3.5m telescope on Calar Alto (Spain) and were analysed by means of non-LTE model atmosphere techniques. Ultraviolet spectroscopy in high resolution of both objects was carried out with the IUE satellite. The spectra are very noisy an cannot be used to measure the line profiles because the stars are faint (V=13.32 and V=13.2 for KPD0005 and RXJ2117, respectively). ------------------------------------------------------------------------------------ 9. Description of previous HST work. ID 2741: NLTE SPECTRAL ANALYSIS OF THE PRE WHITE DWARF PG1159-035 ID 3513: NON- LTE ANALYSIS OF THE POPULATION II POST AGB STARS ROB162 AND K648 ID 4263: NLTE SPECTRAL ANALYSIS OF THREE PG1159 STARS: FINDING THE BOUNDARIES OF THE GW VIR INSTABILITY STRIP involved in all: S. Dreizler, U. Heber, T. Rauch, K. Werner ID 2741: A FOS spectrum with the blue detector, grating G130H and the 0.25"*1.4" aperture has been obtained on May 8, 1992. It has been analysed by comparing the normalized spectrum to synthetic spectra calculated from our NLTE model grid. The effective temperature has been determined with unprecedented accuracy (better than 3%) to be 140,000K). This fully confirmed the result of a previous optical analysis and showed that systematic errors in that analysis are non-existent. Determination of C, N and O abundances is in progress. Due to better known Teff and the larger number of spectral lines the analysis will give much more reliable abundances that the early results based on optical spectroscopy. ID 3513: The observations are currently scheduled for May 1993. ID 4263: Scheduling process has started. The results of the spectroscopic analysis of PG1159-035 have been presented at the 8th European Workshop on White Dwarfs in Leicester, July 1992 and were published in the NATO ASI Series of Kluwer. A letter to A&A is also in preparation. Page 3 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Computer resources: Cray Y-MP and X-MP of the "ZIB" Berlin Cray X-MP of the "Rechenzentrum der Universitaet Kiel" Siemens S400/40 of the "Regionales Rechenzentrum fuer Niedersachsen" VAX 8550 of the "Rechenzentrum der Universitaet Kiel" Cluster of Unix-Workstations of the Institut fuer Theoretische Physik und Sternwarte der Universitaet Kiel Research assistance: Dipl.Ing. G.Jonas (Kiel, data reduction specialist), ------------------------------------------------------------------------------------ 11. Address Information Name: KLAUS WERNER Category: PI Institution: 5584 Address: INSTITUT FUER THEORETISCHE PHYSIK UND STERNWARTE DER UNIVERSITAET KIEL City: D 24098 KIEL State: Zip Code: Country: GERMANY Telephone: +49 431 8804103 Telex (or e-mail): PAS75@RZ.UNI-KIEL.D400.DE ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5322 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 KPD0005+5106 A,109 RA= 00H 08M 18.154S +/- 2000 1 V=13.3 +/- 0.2, TYPE=WDO 0.1S, 2 F-CONT(1250)=3.7 +/- 0.2 E-12 DEC=+51D 23' 16.99" +/- 3 F-CONT(1290)=3.3 +/- 0.2 E-12 0.1", 4 F-CONT(1360)=3.6 +/- 0.2E-12 PLATE-ID=01WL 5 F-CONT(2380)=1.5 +/- 0.2E-13 6 B-V=-0.3+/-0.1 7 E(B-V)=0.1+/-0.1 ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ2117+3412 A,176,184 RA= 21H 17M 08.297S +/- 2000 1 V=13.2 +/- 0.2, TYPE=PG1159 0.1S, 2 F-CONT(1250)=3.7 +/- 0.2 E-12 DEC=+34D 12' 27.82" +/- 3 F-CONT(1290)=3.3 +/- 0.2 E-12 0.1", 4 F-CONT(1360)=3.6 +/- 0.2E-12 PLATE-ID=01W5 5 F-CONT(2380)=1.5 +/- 0.2E-13 6 B-V=-0.3+/-0.1 7 E(B-V)=0.13+/-0.03 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5322 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 KPD0005+510 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=3 1 1.8S 3 1 CYCLE 4 6 BRIGHT=RETURN ONBOARD ACQ FOR LOCATE=YES 1.1 MAP=DEF Comments: STEP TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 1.1 KPD0005+510 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 3 1 CYCLE 4 6 PEAKUP ONBOARD ACQ FOR 1.2-1.5 Comments: STEP TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 1.2 KPD0005+510 HRS ACCUM 2.0 G160M 1230- FP-SPLIT=FOUR 1 14M 40 2 1 CYCLE 4 6 1262 ------------------------------------------------------------------------------------------------------------------------------------ 1.3 KPD0005+510 HRS ACCUM 2.0 G160M 1275- FP-SPLIT=FOUR 1 12M 40 3 1 CYCLE 4 6 1308 ------------------------------------------------------------------------------------------------------------------------------------ 1.4 KPD0005+510 HRS ACCUM 2.0 G160M 1345- FP-SPLIT=FOUR 1 17M 40 4 1 CYCLE 4 6 1378 ------------------------------------------------------------------------------------------------------------------------------------ 1.5 KPD0005+510 HRS ACCUM 2.0 G270M 2957- FP-SPLIT=FOUR 1 32.5M 30 5 1 CYCLE 4 6 3003 ------------------------------------------------------------------------------------------------------------------------------------ 2 RXJ2117+341 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=3 1 1.8S 3 1 CYCLE 4 2 BRIGHT=RETURN ONBOARD ACQ FOR LOCATE=YES 2.1 MAP=DEF Comments: STEP TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2.1 RXJ2117+341 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 3 1 CYCLE 4 2 PEAKUP ONBOARD ACQ FOR 2.2-2.5 Comments: STEP TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2.2 RXJ2117+341 HRS ACCUM 2.0 G160M 1230- FP-SPLIT=FOUR 1 14M 40 2 1 CYCLE 4 2 1262 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 RXJ2117+341 HRS ACCUM 2.0 G160M 1275- FP-SPLIT=FOUR 1 12M 40 3 1 CYCLE 4 2 1308 ------------------------------------------------------------------------------------------------------------------------------------ 2.4 RXJ2117+341 HRS ACCUM 2.0 G160M 1345- FP-SPLIT=FOUR 1 17M 40 4 1 CYCLE 4 2 1378 ------------------------------------------------------------------------------------------------------------------------------------ 2.5 RXJ2117+341 HRS ACCUM 2.0 G270M 2957- FP-SPLIT=FOUR 1 32.5M 30 5 1 CYCLE 4 2 3003 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5322 [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 BRIGHT=RETURN LOCATE=YES MAP=DEF FP-SPLIT=FOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.83 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category WHITE DWARFS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ONBOARD ACQ FOR 1.1; ONBOARD ACQ FOR 1.2-1.5; ONBOARD ACQ FOR 2.1; ONBOARD ACQ FOR 2.2-2.5; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names KPD0005+5106 RXJ2117+3412 ------------------------------------------------------------------------------------------------------------------------------------