Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5403 Report Date: 18-Jul-95:17:18 Version: ********** Check-in Date: ********** 1.Proposal Title: X-RAY EMITTING PLANETARY NEBULAE CYCLE 4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO Sub Category PLANETARY NEBULAE ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Patrick J Harrington 2620 USA 301-405-1517 ------------------------------------------------------------------------------------ 7. Abstract The ROSAT X-ray satellite detected for the first time hot, X-ray emitting gas from from a number of planetary nebulae (PNe). This hot gas is produced in the dynamical interaction of fast stellar winds with the nebular gas. The interaction is poorly understood -- PN dynamical models had failed to predict X-ray emission from PNe. The most plausible hypothesis for the presence of X-ray emission involves stellar wind interactions with inhomogeneous media, leading to mass-loaded outflows. Because mass-loaded outflows are important in a broad astrophysical context, further studies of X-ray emitting PNe are warranted. We propose to study mass-loaded outflows in two optically bright, X-ray emitting PNe, NGC6543 and BD+30 3639, through WFPC2 imaging with a complete set of narrow-band filters. High quality, good signal-to-noise images would provide spectral (through image ratios) information on small angular scales where mass-loading and associated interface phenomena occur. We expect to find radiative shocks, cometary structures, bow-shocks and wind-blown tails, as suggested by numerous ground-based studies and our recent HST observations. Information on these small-scale structures is essential for X-ray emission modeling, and for understanding mass-loaded flows. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.39 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5403 PI: Patrick J Harrington Proposal Title: X-RAY EMITTING PLANETARY NEBULAE CYCLE 4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Patrick J Harrington 2620 USA Kazimierz J Borkowski 2620 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to image both NGC 6543 and BD+30 with the WFPC2 using the full set of narrow filters (excluding the \[Ne V\] and He II filters, since these lines have not been detected in these low-ionization PNe). Thus we would employ 10 filters which cover \[OII\] 3727, \[OIII\] 4363, Hbeta, \[OIII\] 5007, HeI 5876, \[OI\] 6300, Halpha, \[NII\] 6584, \[SII\] 6731, and \[SIII\] 9532. The ratios of these lines will provide many diagnostics: temperature through \[OIII\] 4363/5007; ionization state through \[OII\]/\[OIII\], \[OI\]/\[OII\], \[SII\]/\[SIII\] and HeI/Halpha; shock excitation through Halpha/Hbeta and \[SII\]/Halpha; possible abundance anomalies through \[NII\]/Halpha. Altogether we will have a wealth of information for comparison with predictions of ionization, shock, and conduction front models. Such diagnostics require, however, a higher S/N ratio than simple morphology. Since NGC 6543 is bright, we need to consider possible saturation of the pixels in the strongest lines. If the features are very compact, this is a concern. From the VLA radio map with 0.3" resolution (Balick, Bignell, et al. 1987) we find that the peak flux/arcsec is 0.015 times the total flux. If we apply this factor to the strongest line, \[OIII\] 5007, with a total flux of 1.6 x 10^-9 ergs/cm^2/s, we find a peak electron detection rate of 22 e^-/s/pixel in the PC camera. We would then reach numerical saturation (30000 e^-) in 23 minutes. (The count rate is 4 times greater in the WF camera pixels, but they will be observing the faint halo.) The weakest line is \[OIII\] 4363, which may produce a count rate 10^-3 that of 5007. This line is very important, as the ratio with \[OIII\] 5007 will allow to map the temperature in the more highly ionized gas. A similar estimate for BD+30 shows that the strongest line in this object, \[NII\] 6584, could saturate in 11 minutes. The central stars of both objects will saturate quickly and "bloom" along a few columns of pixels. For NGC 6543, the 11.1 mag star will yield 2600 e^-/sec, or 1.6 x 10^6 e^- for a 10 min exposure. This is still less than the few 10^7 e^- needed to bleed to adjacent columns. The loss of a few columns to blooming is not serious. We will take all WFPC2 images with the central star at the center of the PC array. This will provide the highest resolution and cover all of BD+30 and the whole inner complex of NGC 6543. In the case of the later object, the more sensitive WF arrays will record most of the halo. Altogether, we will take 10 exposures of NGC 6543 and 9 of BD+30. We omit \[OIII\] 4363 from BD+30 as it is likely to be too faint for good S/N. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Both NGC 6543 and BD+30 3639 have been extensively observed to the limit of ground-based resolution. They are among the best observed PNe, and further ground -based work would be unlikely to be very useful. We want to clarify the process by which these objects produce X-ray emission. The leading candidate is mass- loading of the stellar wind, and our experience with A 30 and A 78 indicates that the morphological features characteristic of this process only emerge when we have images with sub-arcsecond resolution. Other phenomena which may be involved, shock and/or conduction fronts, will be intrinsically very narrow, and the highest resolution is needed to pick out the characteristic spectral features from the background of photoionized gas. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We would like to request a special orientation of the WFPC2 for NGC 6543. This request should not significantly restrict scheduling for this object for two reasons: (1) our requirement is to place one of the WF cameras to the west of the central core, and (2) NGC 6543 is located close to the North Ecliptic Pole, and hence in the Continuous Viewing Zone. In order to prevent creating a `hole' in the west, we would like to exclude position angles for the U3 axis from 210 to 330D. We defined this requirement by specifying ORIENT 90D +/- 120D for all exposures of NGC 6543. The scientific justification for this restriction is as follows: the core of NGC 6543 is surrounded by a much fainter, highly filamentary halo 165 arcsec in radius. Most of this halo can be imaged by the WF camera when the PC observes the core, but a particularly bright halo condensation is located in the west. The halo is of great interest. Middlemass, Clegg, and Walsh (1989) found that the halo temperatures are higher than the core temperature by an amount that requires a non-radiative energy source. This discovery was possible with ground-based resolution because in the faint halo, non-photoionization heating is not swamped by intense emission from the photoionized gas. Middlemass et al. (1991) showed that shocks driven into the outer filaments by the (mass- loaded? Dyson 1992) stellar wind would explain the heating. The radiative shocks proposed by Middlemass et al. (1991) are a little over 1 arcsec in thickness. HST observations might well resolve their structure. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ------------------------------------------------------------------------------------ 9. Description of previous HST work. We have been involved in the following HST projects: No. 2266: Post-Asymptotic Giant Branch Evolution in the Magellanic Clouds, PI M.A. Dopita, P. Harrington is a Co-I. Not related beyond the fact that both deal with planetary nebulae. No. 3671, 4226: Ultraviolet Spectroscopy of Hydrogen-Poor Planetary Nebulae, PI P. Harrington, K. Borkowski is a Co-I, cycle 2. Split into two parts for technical reasons. Some relation, in that the cometary structures found in this proposal demonstrate the power of HST imaging to elucidate wind-nebular interactions. Our complementary short (15 min) \[OIII\] 5007 FOC images of A30 and A78 revealed that H-poor gas is concentrated in remarkable ``cometary'' structures (Borkowski et al. 1993). Most of them consist of compact (0.15" -- 0.5") knots with radial tails several arcsec in length. Both stars have energetic winds which are responsible for the knot morphology. These ``cometary'' structures are not visible in our UV FOC images of A30 and A78. Instead, we detected extended emission concentrated around central stars, mostly interior of the optical knots. We interpret this emission in terms of mass-loaded stellar winds, heated mostly by photoelectric emission from dust grains. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The Department of Astronomy of the University of Maryland has an extensive network of Sun workstations, including a number of Sparc X's. This network and supporting technical staff provides an excellent environment for data reduction and modeling. ------------------------------------------------------------------------------------ 11. Address Information Page 4 Name: PATRICK J HARRINGTON Category: PI Institution: 2620 Address: DEPARTMENT OF ASTRONOMY UNIVERSITY OF MARYLAND City: COLLEGE PARK State: MD Zip Code: 20742 Country: USA Telephone: 301-405-1517 Telex (or e-mail): jph@astro.umd.edu ------------------------------------------------------------------------------------ Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5403 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 NGC6543 G,502 PLATE-ID=00T0, 2000 V = -66 1 V=11.23+/- PK96+29D1 RA = 17H 58M 33.29S +/- 2 0.1,TYPE=OF/WR,A(V)=0.0+/-0.15 GSC4212-508 0.07S, 3 SURF-LINE(3728) = 5.2 +/- 1.0 E-12 DEC = +66D 37' 58.9" +/- 4 W-LINE(3728) = 0.17 +/- 0.03 1.0" 5 SURF-LINE(4363) = 3.9 +/- 0.78 E- 6 13 7 SURF-LINE(4861) = 2.2 +/- 0.44 E- 8 11 9 SURF-LINE(5007) = 1.4 +/- 0.29 E- Comments: FLUXVAL_1 REFERS TO CENTRAL STAR. THIS 10 10 IS A CVZ TARGET. SURF-LINE(6731) = 2.4 +/- SURF-LINE(5876) = 3.5 +/- 0.70 E- 0.48 E-12 SURF-LINE(9532) = 1.1 +/- 0.22 E 12 -11 W-LINE(ALL) = 0.17 +/- 0.03 FLUXES ARE SURF-LINE(6300) = 2.0 +/- 0.39 E- LOWER LIMITS FOR BRIGHTEST NEBULAR 13 REGIONS. SURF-LINE(6563) = 6.7 +/- 1.4 E-11 SURF-LINE(6584) = 5.2 +/- 1.0 E-12 ------------------------------------------------------------------------------------------------------------------------------------ 2 PK64+5D1 G,502 PLATE-ID=000J, 2000 V = -66 1 V=12.50+/-0.10,TYPE=WR,A(V)=1.26+/ BD+30D3639 RA = 19H 34M 45.25S +/- 2 -0.09 GSC2655-4032 0.07S, 3 SURF-LINE(3728) = 1.5 +/- 0.30 E- DEC = +30D 30' 59.3" +/- 4 11 1.0" 5 W-LINE(3728) = 0.17 +/- 0.03 6 SURF-LINE(4861) = 2.4 +/- 0.47 E- 7 11 8 SURF-LINE(5007) = 9.4 +/- 1.9 E-13 9 SURF-LINE(5876) = 1.5 +/- 0.30 E- Comments: FLUXVAL_1 REFERS TO CENTRAL STAR. SURF- 10 12 LINE(9532) = 4.5 +/- 0.89 E-11 W-LINE(ALL) SURF-LINE(6300) = 7.8 +/- 1.6 E-13 = 0.17 +/- 0.03 FLUXES ARE LOWER LIMITS TO SURF-LINE(6563) = 9.4 +/- 1.9 E-11 BRIGHTEST NEBULAR REGIONS. SURF-LINE(6584) = 1.1 +/- 0.22 E- 10 SURF-LINE(6731) = 6.1 +/- 1.2 E-12 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5403 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 NGC6543 WFPC2 IMAGE PC1-FIX F375N 1 1800S 5 2 2 CYCLE 4 3 ORIENT 90D +/- 120D / 1.0-1.9 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 NGC6543 WFPC2 IMAGE PC1-FIX F437N 1 2400S 3 4 1 CYCLE 4 3 SAME POS FOR 1.100 -1.900 AS 1.00 ------------------------------------------------------------------------------------------------------------------------------------ 1.2 NGC6543 WFPC2 IMAGE PC1-FIX F487N 1 1400S 23 5 1 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 1.3 NGC6543 WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=0.25 2 800S 60 6 1 CYCLE 4 CR- 1200S 3 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 1.4 NGC6543 WFPC2 IMAGE PC1-FIX F588N 1 1000S 14 7 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 1.5 NGC6543 WFPC2 IMAGE PC1-FIX F631N 1 1800S 5 8 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 1.6 NGC6543 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.25 1 800S 60 9 1 CYCLE 4 CR- 3 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 1.7 NGC6543 WFPC2 IMAGE PC1-FIX F658N 1 1000S 18 10 2 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 1.8 NGC6543 WFPC2 IMAGE PC1-FIX F673N 1 800S 12 10 2 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 1.9 NGC6543 WFPC2 IMAGE PC1-FIX F953N 1 800S 12 10 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 2 PK64+5D1 WFPC2 IMAGE PC1-FIX F375N 1 600S 5 2 2 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 2.2 PK64+5D1 WFPC2 IMAGE PC1-FIX F487N 1 600S 17 4 1 CYCLE 4 3 SAME POS FOR 2.20- 2.900 AS 2.00 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 PK64+5D1 WFPC2 IMAGE PC1-FIX F502N 1 600S 6 5 1 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 2.4 PK64+5D1 WFPC2 IMAGE PC1-FIX F588N 1 600S 8 6 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 2.5 PK64+5D1 WFPC2 IMAGE PC1-FIX F631N 1 1000S 8 7 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5403 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 2.6 PK64+5D1 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=0.4 1 500S 55 8 1 CYCLE 4 CR- 3 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.7 PK64+5D1 WFPC2 IMAGE PC1-FIX F658N CR-SPLIT=0.4 1 500S 65 9 2 CYCLE 4 CR- 3 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.8 PK64+5D1 WFPC2 IMAGE PC1-FIX F673N 1 800S 18 10 2 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ 2.9 PK64+5D1 WFPC2 IMAGE PC1-FIX F953N 1 800S 26 10 3 CYCLE 4 3 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5403 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.25 CR-TOLERANCE=0.0 CR-SPLIT=0.4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.39 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category PLANETARY NEBULAE ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ORIENT 90D +/- 120D / 1.0-1.9 SAME POS FOR 1.100-1.900 AS 1.00 SAME POS FOR 2.20-2.900 AS 2.00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F375N F437N F487N F502N F588N F631N F656N F658N F673N F953N ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6543 PK96+29D1 GSC4212-508 PK64+5D1 BD+30D3639 GSC2655-4032 ------------------------------------------------------------------------------------------------------------------------------------