Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2570c Report Date: 09-May-96:17:12 Version: ********** Check-in Date: ********** 1.Proposal Title: RECENT MASS EJECTION FROM PLANETARY-NEBULA NUCLEI ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO Sub Category LATE EVOLUTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Howard E. Bond STSCI USA 301-338-4718 ASTRONOMER ------------------------------------------------------------------------------------ 7. Abstract We propose HST FOC imagery of two unusual central stars of planetary nebulae. V605 Aq1, the central star of Abell 58, appeared as a 10th-mag red giant for several years around 1920, but is now fainter than 20th mag and appears to lie inside a compact knot of very hydrogen-deficient nebulosity. HST UV images can directly establish that the central star is now extremely hot, providing the first direct evidence for thermal pulses that are predicted to occur in hot pre-white-dwarfs. 0950+139, the central star of EGB 6, is presently a hot white dwarf, surrounded by a compact, unresolved nebula. FOC imagery in the [O III] and H-beta emission lines will establish one of the following. (1) The compact nebula remains unresolved from HST, implying ongoing mass loss from the white dwarf, for which there is no physical understanding at present. (2) The nebula shows sub-arcsecond structure (a hollow shell, blobs, or jets). implying a discrete mass-ejection event, most probably associated with a "self-induced nova" outburst in the fairly recent past. The latter would again provide evidence for an event theoretically predicted to occur in some hot white dwarfs. (3) The nebula shows disk-like structure, suggesting that it arises from ablation of a planetary companion. ------------------------------------------------------------------------------------ 8. Scientific Key Words: WHITE DWARF, PLANETARY NEBULAE, CENTRAL STARS, STELLAR EVOLUTION, MASS LOSS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 3.15 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS FOC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2570c PI: Dr. Howard E. Bond Proposal Title: RECENT MASS EJECTION FROM PLANETARY-NEBULA NUCLEI ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Alvio Renzini BOLOGNA, UNIVERSITY OF ITALY X James W. Liebert ARIZONA, UNIVERSITY OF USA P.I. Howard E. Bond STSCI USA ------------------------------------------------------------------------------------ 2. Scientific Justification. (See original proposal for Scientific Justification) ------------------------------------------------------------------------------------ 3. Description of proposed observations. V605 AQL: For this object, we will search for a very hot star that may lie at the center of the planetary nebula Abell 58. We will use the FOC to obtain high- resolution images of the central [O III] knot, using two ultraviolet filters (F165W and F220W) and an optical filter (F437M) that excludes nebular emission lines. If a hot point source is found, follow-up spectroscopic observations will be obtained with the FOS. In addition, we will obtain images in the [O III] line, using F501N, in order to study the morphology of the central knot. 0950+139: We will again use the FOC, with [O III] (F501N) and H-beta (F486N) filters, in order to study the detailed morphology of the compact nebula surrounding the central star. We are attempting to distinguish between a white dwarf with ongoing mass loss (for which a scale of 10 AU or an unresolved 0.020" is expected) and a discrete ejection event in the recent past or ablation from a planetary companion (for which a resolvable scale of order 100 AU = 0.2" is possible). ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. (See original proposal) ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. (See original proposal) ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. The FOS observations of V605 Aql must be scheduled AFTER the FOC observations, since final details of the spectroscopic observations depend on what is seen with the FOC. NOTE: We are assuming that STScI will calibrate the PSF for the FOC filters that we are using, to sufficient accuracy to study the sub-arcsecond surroundings of our two targets. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. (See original proposal) ------------------------------------------------------------------------------------ 8. Additional comments or special requests. The initial FOC UV imagery of V605 Aql should be regarded both as science images, and as "early acquisitions" from which the precise position and brightness of the central point source (if any) will be determined. ------------------------------------------------------------------------------------ 9. Description of previous HST work. N/A ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). (See original proposal) ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: HOWARD E. BOND Category: PI Institution: SPACE TELESCOPE SCIENCE INSTITUTE Address: 3700 SAN MARTIN DR. City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2570c [ 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 V605AQL-KNOT STAR; CENTRAL STAR; PLATE-ID=02CT, J2000 1 V=21 ABELL58- WHITE DWARF; RA=19H 18M 20.51S +/- 1", CENTRAL-KNOT DEGENERATE STAR; DEC=+01D 46' 59.4" +/- 1" PLANETARY NEBULA; KNOT; ------------------------------------------------------------------------------------------------------------------------------------ 2 V605AQL-STAR STAR; CENTRAL STAR; TBD-EARLY, J2000 BKG 1 V=21 ABELL58- WHITE DWARF; RA=19H 18M 20.51S +/- 2", CENTRAL-STAR DEGENERATE STAR; DEC=+01D 46' 59.4" +/- 2" PLANETARY NEBULA; ------------------------------------------------------------------------------------------------------------------------------------ 3 0950+139 STAR; TYPE=DA; CENTRAL PLATE-ID=01X2, J2000 1 V=16.0 EGB6-CENTRAL STAR; WHITE DWARF; RA=09H 52M 58.98S +/- 0.7", 2 B-V=-0.30 -STAR DEGENERATE STAR; DEC=+13D 44' 33.7" +/- 0.7" PLANETARY NEBULA; ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2570c [ 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 V605AQL- FOC/96 IMAGE 512X512 F165W 1 800S 1 1 SAME ORIENT FOR 2- KNOT 4 AS 1 CYCLE 1 / 1-11 ------------------------------------------------------------------------------------------------------------------------------------ 2 V605AQL- FOC/96 IMAGE 512X512 F220W 1 800S 1 1 KNOT ------------------------------------------------------------------------------------------------------------------------------------ 3 V605AQL- FOC/96 IMAGE 512X512 F437M 1 800S 1 1 KNOT ------------------------------------------------------------------------------------------------------------------------------------ 4 V605AQL- FOC/96 IMAGE 512X512 F501N 1 800S 1 1 KNOT ------------------------------------------------------------------------------------------------------------------------------------ 5 V605AQL- FOS/BL ACQ/ 4.3 MIRROR 1 120S 1 1 ONBOARD ACQ FOR 6 STAR BINARY REQ DATA FROM 1-4 / 5-9 Comments: FOR LINES 5-9, PRECISE TARGET LOCATION, EXPOSURE TIMES, AND CHOICE OF SCIENCE APERTURE WILL BE DETERMINED ON BASIS OF THE FOC OBSERVATIONS IN LINES 1-4. ENTRIES ON LINES 5-9 ARE PROVISIONAL. ------------------------------------------------------------------------------------------------------------------------------------ 6 V605AQL- FOS/BL ACCUM 0.5 G160L 1150- 1 2500S 10 1 1 STAR 2200 ------------------------------------------------------------------------------------------------------------------------------------ 7 V605AQL- FOS/RD ACQ/ 4.3 MIRROR 1 90S 1 1 ONBOARD ACQ FOR 8- STAR BINARY 9 ------------------------------------------------------------------------------------------------------------------------------------ 8 V605AQL- FOS/RD ACCUM 0.5 PRISM 1850- 1 2500S 10 1 1 STAR 8950 ------------------------------------------------------------------------------------------------------------------------------------ 9 V605AQL- FOS/RD ACCUM 0.5 G650L 3750- 1 2500S 10 1 1 STAR 7500 ------------------------------------------------------------------------------------------------------------------------------------ 10 0950+139 FOC/96 IMAGE 512X512 F486N 1 800S 1 1 SAME ORIENT FOR 11 AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 11 0950+139 FOC/96 IMAGE 512X512 F501N 1 800S 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2570c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 FOS/BL FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 3.15 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category LATE EVOLUTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SAME ORIENT FOR 2-4 AS 1; CYCLE 1 / 1-11 ONBOARD ACQ FOR 6; REQ DATA FROM 1-4 / 5-9 ONBOARD ACQ FOR 8-9; SAME ORIENT FOR 11 AS 10 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F165W F220W F437M F501N MIRROR G160L PRISM G650L F486N ------------------------------------------------------------------------------------------------------------------------------------ Target Names V605AQL-KNOT ABELL58-CENTRAL-KNOT V605AQL-STAR ABELL58-CENTRAL-STAR 0950+139 EGB6-CENTRAL-STAR ------------------------------------------------------------------------------------------------------------------------------------