Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4566c Report Date: 09-May-96:19:42 Version: ********** Check-in Date: ********** 1.Proposal Title: POST ASYMPTOTIC GIANT BRANCH EVOLUTION IN THE MAGELLANIC CLOUDS - SPECTROSCOPY: CYCLE 3 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO 3 Long Term yrs 2266 Sub Category PLANETARY NEBULAE ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Michael A Dopita MT. STROMLO AND SIDING SPRIN ------------------------------------------------------------------------------------ 7. Abstract Planetary Nebulae (PN) represent a critical stage of stellar evolution which is relatively poorly understood. More reliable observational estimates of stellar luminosity, mass, effective temperature, and age are required to constrain evolutionary models and determine mass-loss rates, He shell flash phases, and the role of dredge-up. This proposal represents the continuation of our systematic and definitive study with HST of a large sample of nebulae at known distance in the Magellanic Clouds and requires approximately 50 hours for completion. All parameters needed for confrontation of theory with observation can be derived from direct PC imaging and FOS spectra in the 1150-3200A range. The images give spatial structure, sizes, ionized mass, dynamical ages, and an estimate of the final mass-loss rate on the AGB. The spectra will be combined with the images and with stellar atmospheric and evolutionary models to derive the effective temperature, luminosity, and core mass of each of the exciting stars. These data will define the evolutionary status of each of the PN observed. We will use two independent ionization codes to interpret the spatial structure derived from PC images and the FOS data, in conjuction with optical and IR spectra. This analysis will also yield chemical abundances of many elements, including the astrophysically important species He, C, N, O, and Si. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.04 par: 0 10. Num targs pri: 6 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4566c PI: Michael A Dopita Proposal Title: POST ASYMPTOTIC GIANT BRANCH EVOLUTION IN THE MAGELLANIC CLOUDS - SPECTROSCOPY: CYCLE 3 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Michael A Dopita MT. STROMLO AND SIDING SPRING AUSTRALIA OBSERVATORIES Stephen J Meatheringham MT. STROMLO AND SIDING SPRING AUSTRALIA OBSERVATORIES Peter R Wood MT. STROMLO AND SIDING SPRING AUSTRALIA OBSERVATORIES Ralph C Bohlin STSCI USA Holland C Ford STSCI USA Emanuel Vassiliadis STSCI USA Patrick J Harrington UNIVERSITY OF MARYLAND USA Theodore P Stecher NASA GODDARD SPACE FLIGHT CENTER USA Stephen P Maran NASA GODDARD SPACE FLIGHT CENTER USA Page 3 ------------------------------------------------------------------------------------ 3. Description of proposed observations. Imaging Program: This part of the program has been transferred to proposal 4940, which must be completed before the FOS observations are attempted. Cycle 3 UV Spectrophotometry: We are undertaking FOS spectrophotometry during Cycle 3 in the range 1150 - 5000 Angstroms using the G130H and G190H gratings, and the PRISM. We aim to achieve an average signal to noise in the nebular continuum of 3 per pixel. Since it proves to be very inefficient to do separate AQU/PEAK for both the blue and red sides of the spectrograph, we have elected to observe on the blue side only, accepting the lower efficiency in order to have data in the G130H bandpass. Similarly, Cycle 2 experience has shown us that the PRISM gives adequate resolution in the pass-band previously covered by the G270H grating, and additional coverage into the optical. Since the Magellanic Clouds are close enough that even the faintest PN can be detected, the flux and spectral distribution of the PN nuclei can be measured over their entire ~5 mag in luminosity. Our aim is to accomplish this objective, and to achieve a good detection of the central star against the nebular continuum, even when the stellar flux is only 10% of this nebular continuum. This objective will also ensure that uniform, high quality, high dynamic range nebular spectra are obtained for the full range of nebular conditions. For the purposes of computing exposure times for spectra, a mean extinction E(B-V) of 0.15 and an LMC or SMC-like extinction law have been assumed. The counts/diode/second C-d, is given in terms of the flux at 1650 Angstroms (F_1650):log(C_d) =- f(Phi) C + log(F_1650), where C has the values 13.53 (G130H, blue digicon) and 13.56 (G190H, blue digicon) and 14.10 (G270H,again the blue digicon). The function f(Phi) is a function of the diameter of the PN, accounting for spherical abberation and is calculated from a modelling of the PSF and the PN. These data will be combined with our ground-based data of comparable quality covering the wavelength range 3200 - 10000 Angstroms. In the decade of frequency covered by these observations, we will see emission lines of the astrophysically important elements such as He, C, N, O, Si and S in the full range of ionisation stages expected to be present in the nebula. For this reason, and also because the allowable nebular models are strongly constrained by the imaging results, we expect that the chemical abundances we will derive will be much more accurate than any previously obtained. The proper method of acquisition can only be determined once the PC images from proposal 4940 have been analysed. As was found for the Cycle 2 proposal 3441, most acquisitions will probably become BINARY ACQs, and will consequently reduce the overhead times significantly. This will be the case for objects found to have a diameter less than a FOS diode width (0.35 arcsec). For those targets larger than a FOS diode width, a 5x5 PEAK-UP acquistion, with 0.5 arcsec steps using the 1 arcsec aperture, will be performed. This gives an effective field coverage of 3x3 arcsec, and will achieve 0.25*(2**0.5) = 0.35 arcsec accuracy on any PN within 1.25 arcsec of the initial pointing position. References: Jacoby, G., 1980, Ap. J. Suppl. Ser.,42, p. 1 Wood, P.R., Bessell, M.S., and Dopita, M.A., 1986, Ap. J.,311, p. 632 Wood, P.R., Meatheringham, S.J., Dopita, M.A., and Morgan, D.H., 1987, Ap. J., 320, p. 178 Page 4 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The angular diameters of the Magellanic Cloud PN lie in the range 0.05 - 4.0 arcseconds, ideally suited to the HST capabilities. Some of us have obtained low resolution UV spectra of a few of these objects using the IUE satellite. However, only the brightest objects are observable, many of the same objects chosen for the GTO program. The UV data is crucial for measurement of the stellar flux distribution and to obtain densities and ionic abundances for dominant ionisation stages of many elements. Only the combination of high resolution and a spectral range which extends shortward of the peak in the hydrogen two-photon nebular continuum (about 1450 Angstroms) will enable us to detect the star in the cases where the nebular continuum is strong. Our HST program is supported by a comprehensive and continuing ground-based program. We have used the 1-metre, 2.3-metre and 3.9-metre telescopes at Siding Spring to measure fluxes, sizes, expansion velocities, radial velocities and nebular spectra from 3200 to 10000 Angstroms. These observations already provide an excellent set of homogeneous and high-quality data which gives the best possible ground-based characteristics of the Magellanic Cloud population of PN. this data set will allow us to extend our population classifications from the HST subset to the entire population of PN in the Magellanic Clouds. References: See question 3. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. An high-quality astrometric determination of the nebular centroid will be obtained on the basis of the PC images, we may seek to give an improved estimate of the position based on these data, for input to the Cycle 3 FOS spectroscopy program. Based on our experience with our Cycle 2 FOS exposures, the imaging program must be completed first to allow a proper determination of the method of FOS acquistion. The EARLY ACQ imaging proposal (4940) needs to be executed sufficiently early for the FOS spectroscopy (this proposal) to be completed before the end of Cycle 3. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. The FOS spectroscopic observations are required to be carried out in SEQ NO GAP mode because we need to be sure that the same part of the nebula is being observed in all three spectral bands. This is a requirement for the spectrophotometry to be valid. Page 5 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. All PC images and FOS spectra will be reduced at STScI and then distributed by H.Ford and R.Bohlin to the team members. The dynamical ages of the nebulae will be derived by creating models of expanding prolate shells with varying azimuthal intensities whose projections onto the sky reproduce the [O III] line profiles (already obtained for the whole sample, Dopita et. al. 1985, 1988) and the PC image structure. The software needed for this program has already been written by H.Ford and his collaborators. We plan to combine the FOS UV spectrophotometry with ground-based and near-IR spectrophotometry to produce dereddened spectra. Theoretical models of the nebular continuum and of the central star will be used to separate the two continuum contributions and to place the star on the L-T(eff) diagram. By using the dynamical age already obtained, we will compare the evolutionary tracks implied for the PN nuclei with the theoretical evolutionary models (e.g. Wood and Faulkner 1986). This will enable us to determine the mass distribution of the PN nuclei, to determine whether PN ejection occurs at the time of the Helium shell flash, and to put strong observational restraints on the post-AGB mass-loss. Using the observed parameters of the central star, the FOS spectrophotometry and ionisation structure implied by the PC images, we will construct detailed photoionisation models using independent codes by Harrington, and by Dopita and Binette. The nebular size and structure, the shape of the stellar spectrum, and the ratio of stellar to nebular continua will enable us to obtain the mean ionisation parameter (Q), the ionisation temperature (T*), and the optical thickness of the nebula, which together define the nebular model. The FOS spectra are vital in the determination of the abundances of the dominant ionic species of N, C and Si. Likewise the ratio of the C III] doublet at 1906, 1909 Angstroms will give the electron density in the region of the PN containing the dominant ionisation stage. From the complete spectrophotometric data we will be able to derive the abundances of the elements : He, C, N, O, Ne, S, Cl, and Ar and possibly, Mg, Fe and Ni as well. We wish to stress that the PC nebular images and the wealth of FOS ultraviolet data will enable us to construct models with a level of detail which has previously been obtained in only a few Galactic PN such as NGC7662 (Harrington et. al. 1982), and IC3918 (Clegg et. al. 1987). References: Clegg, R.E.S., Harrington, J.P., Barlow, M.J., and Walsh, J.R., 1987, Ap. J. vol. 314, p. 575 Dopita, M.A., Ford, H.C., Lawrence, C.J., and Webster, B.L.,1985, Ap. J. vol. 296, p. 390 Dopita, M.A., Meatheringham, S.J., Webster, B.L., and Ford, H.C.,1988, Ap. J. vol. 327, p. 639 Harrington, J.P., Seaton, M.J., Adams, S., and Lutz, J.H., 1982, M.N.R.A.S., vol. 199, p. 517 Wood, P.R., and Faulkner, D.J., 1986, Ap. J., vol. 307, p. 659 ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Since the full analysis of the data will take a total of three years, we request that release of the data be delayed a full year after the completion of the observational program. Full archival use will be made of data obtained under the GTO program on Magellanic Cloud PN as this is released. Primary team responsibilities are as follows: 1. Image reduction, astrometry, analysis and distribution : Ford and Bohlin. 2. FOS data reduction and distribution : Bohlin and Meatheringham 3. Analysis and evolution of central stars : Dopita, Wood, Bohlin, Maran and Stecher 4. Nebular modelling and chemical composition : Dopita, Harrington, and Maran 5. Analysis of stellar populations and astrophysical interpretation : all team. ------------------------------------------------------------------------------------ 9. Description of previous HST work. As described above, this project was awarded time for HST imaging in Cycle 1. In Cycle 2, the objects which were imaged in [O III] will be subjected to spectroscopic investigation. Page 6 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The manpower, fiscal and hardware resources necessary to support the work of the P.I. and the other Australian members of this group will be supplied from within the internal budget of MSSSO as necessary. Funding will also be available to support any short overseas visits that may be necessary to coordinate activities of the various team members, as summarised in question 8. ------------------------------------------------------------------------------------ 11. Address Information Name: MICHAEL A DOPITA Category: PI Institution: Mt. Stromlo and Siding Spring Obs Address: PRIVATE BAG WESTON CREEK P.O. City: WESTON State: Zip Code: ACT 2611 Country: AUSTRALIA Telephone: (011 61) 6 2490212 Telex (or e-mail): AA62270 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4566c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 101 SMC-SMP22 H,502 RA = 00H 58M 37.22S +/- 2000.0 V = 153 1 F-CONT(1650) = 1.8 +/- 0.8 E-15 N67 LN333 0.02S, 2 F-LINE(1666) = 1.9 +/- 0.6 E-14 DEC = -71D 35' 48.79" +/- 3 F-LINE(5007) = 3.8 +/- 0.1 E-13 0.1" 4 SURF-LINE(5007) = 3.0 +/- 1.0 E-12 5 W-LINE(5007) = 1.0, SIZE = 0.4 Comments: FOR ALL TARGETS, IDENT # FROM FOLLOWING REFS: SMP=SANDULEAK ETAL.1978.PASP 90,621 N = HENIZE 1956. AP J. SUPPL. 2,315 LN = LINDSAY 1961. ASTR. J. 66, 169 ------------------------------------------------------------------------------------------------------------------------------------ 104 LMC-SMP61 H,502 RA = 05H 24M 35.97S +/- 2000.0 V = 193 1 F-CONT(1650) = 2.1 +/- 0.6 E-14 N203 0.02S, 2 F-LINE(1666) = 1.5 +/- 0.3 E-13 DEC = -73D 40' 39.68" +/- 3 F-LINE(5007) = 2.9 +/- 0.1 E-12 0.1" 4 SURF-LINE(5007) = 1.5 +/- 1.0 E-11 5 W-LINE(5007) = 1.0, SIZE = 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 105 LMC-SMP67 H,502 RA = 05H 29M 15.75S +/- 2000.0 V = 289 1 F-CONT(1650) = 2.0 +/- 0.6 E-14 N53 0.02S, 2 F-LINE(1666) = 2.7 +/- 0.6 E-14 DEC = -67D 32' 47.58" +/- 3 F-LINE(5007) = 5.4 +/- 0.1 E-13 0.1" 4 SURF-LINE(5007) = 2.8 +/- 1.0 E-12 5 W-LINE(5007) = 1.0, SIZE = 0.5 ------------------------------------------------------------------------------------------------------------------------------------ 106 LMC-SMP101 H,502 RA = 06H 23M 40.39S +/- 2000.0 V = 281 1 F-CONT(1650) = 2.1 +/- 0.8 E-15 0.02S, 2 F-LINE(1666) = 7.3 +/- 0.6 E-14 DEC = -69D 10' 38.35" +/- 3 F-LINE(5007) = 1.5 +/- 0.1 E-12 0.1" 4 SURF-LINE(5007) = 1.3 +/- 1.0 E-12 5 W-LINE(5007) = 1.0, SIZE = 1.2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4566c [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE # FOS/BL ACQ/ 4.3 MIRROR BRIGHT=720000 1 1S 1 1 CYCLE 3 / 3.0- BINACQ BINARY FAINT=660 106.4 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE # FOS/BL ACQ/ 1.0 MIRROR TYPE=UP 1 1S 1 1 PKUPBL PEAK SEARCH-SIZE-X=5 SCAN-STEP-X=0.5 SEARCH-SIZE-Y=5 SCAN-STEP-Y=0.5 ------------------------------------------------------------------------------------------------------------------------------------ 5 DEFINE # FOS/BL ACCUM 1.0 G130H 1300 1 1S # 1 1 FOS130 ------------------------------------------------------------------------------------------------------------------------------------ 6 DEFINE # FOS/BL ACCUM 1.0 G190H 1900 1 1S # 1 1 FOS190 ------------------------------------------------------------------------------------------------------------------------------------ 7 DEFINE # FOS/BL ACCUM 1.0 PRISM 1 1S # 1 1 BLUPRI ------------------------------------------------------------------------------------------------------------------------------------ 101.1 USE SMC-SMP22 X10.0 SEQ 101.1 - 101.4 PKUPBL NO GAP ONBOARD ACQ FOR 101.2 - 101.4 ------------------------------------------------------------------------------------------------------------------------------------ 101.2 USE SMC-SMP22 X1700 3 FOS130 ------------------------------------------------------------------------------------------------------------------------------------ 101.3 USE SMC-SMP22 X700 3 FOS190 ------------------------------------------------------------------------------------------------------------------------------------ 101.4 USE SMC-SMP22 X200 3 BLUPRI ------------------------------------------------------------------------------------------------------------------------------------ 104.1 USE LMC-SMP61 X33.0 SEQ 104.1 - 104.4 BINACQ NO GAP ONBOARD ACQ FOR 104.2 - 104.4 ------------------------------------------------------------------------------------------------------------------------------------ 104.2 USE LMC-SMP61 X400 3 FOS130 ------------------------------------------------------------------------------------------------------------------------------------ 104.3 USE LMC-SMP61 X150 3 FOS190 ------------------------------------------------------------------------------------------------------------------------------------ 104.4 USE LMC-SMP61 X100 3 BLUPRI ------------------------------------------------------------------------------------------------------------------------------------ 105.1 USE LMC-SMP67 X33.0 SEQ 105.1 - 105.4 BINACQ NO GAP ONBOARD ACQ FOR 105.2 - 105.4 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4566c [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 105.2 USE LMC-SMP67 X1100 3 FOS130 ------------------------------------------------------------------------------------------------------------------------------------ 105.3 USE LMC-SMP67 X500 3 FOS190 ------------------------------------------------------------------------------------------------------------------------------------ 105.4 USE LMC-SMP67 X150 3 BLUPRI ------------------------------------------------------------------------------------------------------------------------------------ 106.1 USE LMC-SMP101 X5.0 SEQ 106.1 - 106.4 PKUPBL NO GAP ONBOARD ACQ FOR 106.2 - 106.4 ------------------------------------------------------------------------------------------------------------------------------------ 106.2 USE LMC-SMP101 X1000 3 FOS130 ------------------------------------------------------------------------------------------------------------------------------------ 106.3 USE LMC-SMP101 X500 3 FOS190 ------------------------------------------------------------------------------------------------------------------------------------ 106.4 USE LMC-SMP101 X150 3 BLUPRI ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4566c [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT FAINT TYPE=UP SEARCH-SIZE-X=5 SCAN-STEP-X=0.5 SEARCH-SIZE-Y=5 SCAN-STEP-Y=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.04 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category PLANETARY NEBULAE ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 3 / 3.0-106.4 SEQ 101.1 - 101.4 NO GAP; ONBOARD ACQ FOR 101.2 - 101.4; SEQ 104.1 - 104.4 NO GAP; ONBOARD ACQ FOR 104.2 - 104.4; SEQ 105.1 - 105.4 NO GAP; ONBOARD ACQ FOR 105.2 - 105.4; SEQ 106.1 - 106.4 NO GAP; ONBOARD ACQ FOR 106.2 - 106.4; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G130H G190H PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names SMC-SMP22 N67 LN333 LMC-SMP61 N203 LMC-SMP67 N53 LMC-SMP101 ------------------------------------------------------------------------------------------------------------------------------------