8726( 3) - 09/25/01 11:47 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8726 Version: 3 Check-in Date: 25-Sep-2001 11:46:10 1.Proposal Title: Cometary Knots in Planetary Nebulae ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: C. O'Dell Vanderbilt University CoI: Dr. Bruce Ballick University of Washington N CoI: Dr. Andreas Burkert Max Planck Institute for Astronomy- N Heidelberg CoI: Dr. Arsen Hajian United States Naval Observatory N CoI: Dr. William Henney Institute of Astronomy, UNAM, Morelia N ------------------------------------------------------------------------------------ 5. Abstract Cometary Knots trap a significant fraction of all the ejected material in the closest of the Planetary Nebulae, NGC 7293. This means that these knots may transport material into free space in a highly preserved state, possibly as solid bodies, a consequence of some import to understanding the composition of the interstellar medium. Recent HST and VLT results indicate that the Cometary Knots are actually quite common among a sampling of nearby Planetary Nebulae, so that it is likely they are a natural part of the expulsion of material by intermediate mass stars. We propose second epoch observations of the Cometary Knots in NGC 7293 in order to get a better idea of just how these objects are formed by comparison of their spatial motions with that of the ambient gas. We also propose observations of four Planetary Nebulae that give indications of the presence of Cometary Knots at different phases of development. These observational data will be used to quantitatively assess the masses, ubiquity, and probable survival of Cometary Knots in the sample. Added to our knowledge of the Cometary Knots in NGC 7293, the set should be large enough to allow drawing general conclusions about their role in the Planetary Nebula phenomenon and the interstellar medium. ------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 2] Observations Description ------------------------ The images obtained in this program will be straightforward WFPC2 observations in the emission line filters most relevant for analyzing the ionization structure of the Cometary Knots and the F547M filter required for calibration of the emission line filter images into cgs units (O'Dell 1998, AJ, 115, 263; O'Dell &\ Doi, 1999, PASP, in press). We will use the same pointings and orientation values as previous HST observations of these objects. The emission line filters selected are those necessary to complete the full range of ionization conditions in the nebulae, these being different for each object since the original observations were obtained in different filters for various observing programs. The only case where a filter is duplicated (on a particular object) is NGC 6720, where the original program observations in F469N were underexposed. Exposure times were primarily calculated by scaling from the existing WFPC2 emission line images and from the spectroscopically known relative intensities of the lines. The exception to this is the set of observations of IC4406, where the original WFPC2 observations were made in the F555W and F814W filters, which are so broad that they don't have a primary emission line for use as reference in scaling. In this case, the exposure times were calculated from comparison of this object's H Beta\ surface brightness with that of the other objects and scaling according to the relative line intensities. The NGC 7293 observations are a repeat of the exposure times and pointing of our initial WFPC2 field(O'Dell &\ Handron, 1996, AJ, 111, 1630). Since our goal is to determine the tangential velocities by comparison with the earlier observations, we only need to repeat observations in F656N and F658N, as the CK are weak in F502N and F547M. Use of both filters is essential since the greater strength of the N II 6548 and 6583 Angstrom\ lines strongly affect the H Alpha\ F656N filter's signal. Observations made in September, 2000 would have a time base of 6 years from the first images. The minimum expected tangential motion will be the equivalent of the observed radial velocities of 10 kms, which would give motions of 0.6 WFC pixels. The PI's participation in a study of similar objects in the Orion Nebula (Bally et al. 1999, submitted) indicates a detection threshold of about 0.14 WFC pixels. These images should yield measurements at least five times the measurement error and firmly establish the spatial motion of the CK. Various theories of their origins predict different relative velocities visavie the main body of the nebula, so that these results would help in our understanding the origin of the objects. NGC 6853 is significantly lower in surface brightness than the new other nebulae in this program (by about a factor of six). Moreover, it has only been observed in the H Alpha\ line and has a hot central star, so it requires observation in all the filters of the program. This requires four orbits of observations, almost as much as the sum of the other three new objects. If it is necessary to reduce the total number of orbits from the 14 requested, dropping NGC 6853 would allow a big fractional reduction in the orbits needed. We hope this is not necessary, as this nearby planetary promises the best spatial resolution of the Cometary Knots after NGC 7293. Only one PN (Sh 2-216) is known to have an accurate distance closer than either of these two objects (Harris et al. 1998, IAU180, 40), but, is much too low a surface brightness for inclusion in this study. These imaging observations will be supported in their analysis by an existing set of velocity cube images of (Balick et al. 1987, AJ, 94, 1641). The NGC 2392 observations will be supplemented by KPNO 4-m observations in January, 2000 at position angles corresponding to the outermost linear features, thus possibly providing dynamical information as to whether these are rapidly moving features and if the one aligned with the previously known high velocity outflow is indeed the driving jet. Our team is particularly well composed to execute and analyze these observations. O'Dell and Ballick have between them worked on PN for over 70 years, including developing theoretical and empirical dynamic models of the class and detailed analysis of NGC 2392 in particular. O'Dell will direct and coordinate the overall program and perform the flux calibration of the images using the most rigorous techniques. As demonstrated in the final section of this proposal, he has an established record for timely production of papers based on his HST observations. In this case the team has been composed for the interpretive tools that they can bring to the analysis of the results and their ability to cooperate as a goal oriented team. Balick will draw on his substantial body of information on the appearance and kinematics of the PN obtained both with HST and large ground telescopes. Hajian has participated with Balick as leaders in defining and characterizing the FLIER phenomena in PN. Hajian is also the PI of a long-term WFPC2 project for measuring distances to PN by expansion parallaxes, a program which requires advanced 3-D modeling capabilitity, which will be useful to the present program. Henney is the leading practitioner of modeling compact photoionized sources both radiatively and hydrodynamically, with his models developed for explaining the proplyds in the Orion Nebula Cluster finding direct application to the CK which are the center of this proposal. O'Dell and Burkert have published several papers on the CK in the Helix nebula and Burkert is an expert in the area of instabilities and fragmentation. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PK36-57D1W ISM, Planetary Nebula RA = 22H 29M 37.72S +/- 0.01S, 2000 SURF-LINE(6563)=6.6+/-0.5e-5 DEC = -20D 47' 58.47" +/- 0.1" Coordinate Source: OTHER_SOURCE Comments: Above value is for NGC 7293. Exposures for other nebulae in this program are determined from earlier WFPC2 observations. 2 NGC6853 ISM, Planetary Nebula RA=19H 59M 32.5S +/- 0.100S, 2000 SURF-LINE(6563)=6.6+/-0.5e-5 DEC= 22D 43' 11.0" +/- 1.00" Coordinate Source: OTHER_SOURCE Comments: Above value is for NGC 7293. Exposures for other nebulae in this program are determined from earlier WFPC2 observations. 3 NGC6720E ISM, Planetary Nebula RA = 18H 53M 35.00S +/- 1", DEC 2000 V = 15.70 = 33D 1' 43" +/-1", PLATE- ID=02UB Coordinate Source: GSC_SURVEY_PLATE Comments: Coordinates and flux are for central star. 4 NGC2392 ISM, Planetary Nebula RA=07H 29M 10.77S +/- 1", 2000 SURF-LINE(6563)=6.6+/-0.5e-5 DEC=20D 54' 42.5" +/- 1" Coordinate Source: OTHER_SOURCE Comments: Above value is for NGC 7293. Exposures for other nebulae in this program are determined from earlier WFPC2 observations. 5 IC4406 ISM, Planetary Nebula RA = 14H 22M 26.20S +/- 1", DEC 2000 SURF-LINE(6563)=6.6+/-0.5e-5 =-44D 9' 4" +/-1", PLATE- ID=011M Coordinate Source: GSC_SURVEY_PLATE Comments: Above value is for NGC 7293. Exposures for other nebulae in this program are determined from earlier WFPC2 observations. 8726( 3) - 09/25/01 11:47 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 253.560D TO 253.562D On Hold Comments: Additional Comments: All observations should be made at the same ORIENT value. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 PK36-57D1W WFPC2 IMAGE WF4-FIX F656N 6564 1 42 M ------------------------------------------------------------------------------------------------------------------------------------ 102 PK36-57D1W WFPC2 IMAGE WF4-FIX F656N 6564 1 43 M ------------------------------------------------------------------------------------------------------------------------------------ 103 PK36-57D1W WFPC2 IMAGE WF4-FIX F658N 6590 1 43 M ------------------------------------------------------------------------------------------------------------------------------------ 104 PK36-57D1W WFPC2 IMAGE WF4-FIX F658N 6590 1 43 M ------------------------------------------------------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 5] Visit: 02 Visit Priority: Visit Requirements: ORIENT 59.866D TO 59.868D On Hold Comments: Additional Comments: All observations should be made at the same ORIENT value. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 201 NGC6853 WFPC2 IMAGE WFALL F658N 6590 1 42 M ------------------------------------------------------------------------------------------------------------------------------------ 202 NGC6853 WFPC2 IMAGE WFALL F673N 6732 1 43 M ------------------------------------------------------------------------------------------------------------------------------------ 203 NGC6853 WFPC2 IMAGE WFALL F502N 5012 1 10 M ------------------------------------------------------------------------------------------------------------------------------------ 204 NGC6853 WFPC2 IMAGE WFALL F547M 5476 1 15 M ------------------------------------------------------------------------------------------------------------------------------------ 205 NGC6853 WFPC2 IMAGE WFALL F656N 6564 2 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 206 NGC6853 WFPC2 IMAGE WFALL F502N 5012 1 420 S ------------------------------------------------------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 6] Visit: 03 Visit Priority: Visit Requirements: ORIENT 78.501D TO 78.502D On Hold Comments: Additional Comments: All observations should be made at the same ORIENT value. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 301 NGC6720E WFPC2 IMAGE WF3-FIX F656N 6564 3 160 S POS TARG 37.5, 37.5 ------------------------------------------------------------------------------------------------------------------------------------ 302 NGC6720E WFPC2 IMAGE WF3-FIX F469N 4694 3 400 S POS TARG 37.5, 37.5 ------------------------------------------------------------------------------------------------------------------------------------ 303 NGC6720E WFPC2 IMAGE WF3-FIX F673N 6732 3 240 S POS TARG 37.5, 37.5 ------------------------------------------------------------------------------------------------------------------------------------ 304 NGC6720E WFPC2 IMAGE WF3-FIX F547M 5476 3 100 S POS TARG 37.5, 37.5 ------------------------------------------------------------------------------------------------------------------------------------ 305 NGC6720E WFPC2 IMAGE WF3-FIX F658N 6590 2 160 S POS TARG 37.5, 37.5 ------------------------------------------------------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 7] Visit: 04 Visit Priority: Visit Requirements: ORIENT 71.001D TO 71.002D On Hold Comments: Additional Comments: All observations should be made at the same ORIENT value. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 401 NGC2392 WFPC2 IMAGE WF3 F673N 6732 3 480 S ------------------------------------------------------------------------------------------------------------------------------------ 402 NGC2392 WFPC2 IMAGE WF3 F469N 4694 1 360 S ------------------------------------------------------------------------------------------------------------------------------------ 403 NGC2392 WFPC2 IMAGE WF3 F487N 4865 1 100 S ------------------------------------------------------------------------------------------------------------------------------------ 404 NGC2392 WFPC2 IMAGE WF3 F469N 4694 2 360 S ------------------------------------------------------------------------------------------------------------------------------------ 405 NGC2392 WFPC2 IMAGE WF3 F547M 5476 3 200 S ------------------------------------------------------------------------------------------------------------------------------------ 406 NGC2392 WFPC2 IMAGE WF3 F487N 4865 1 100 S ------------------------------------------------------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 8] Visit: 05 Visit Priority: Visit Requirements: ORIENT 106.205D TO 106.207D On Hold Comments: Additional Comments: All observations should be made at the same ORIENT value. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 501 IC4406 WFPC2 IMAGE PC1 F656N 6564 3 180 S ------------------------------------------------------------------------------------------------------------------------------------ 502 IC4406 WFPC2 IMAGE PC1 F658N 6590 3 180 S ------------------------------------------------------------------------------------------------------------------------------------ 503 IC4406 WFPC2 IMAGE PC1 F673N 6732 3 180 S ------------------------------------------------------------------------------------------------------------------------------------ 504 IC4406 WFPC2 IMAGE PC1 F502N 5012 3 200 S ------------------------------------------------------------------------------------------------------------------------------------ 505 IC4406 WFPC2 IMAGE PC1 F547M 5476 2 200 S ------------------------------------------------------------------------------------------------------------------------------------ 8726( 3) - 09/25/01 11:47 - [ 9] Summary Form for Proposal 8726 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF4-FIX WFALL WF3-FIX WF3 PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 253.560D TO 253.562D ORIENT 59.866D TO 59.868D ORIENT 78.501D TO 78.502D POS TARG 37.5, 37.5 ORIENT 71.001D TO 71.002D ORIENT 106.205D TO 106.207D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N F658N F673N F502N F547M F469N F487N ------------------------------------------------------------------------------------------------------------------------------------ Target Names PK36-57D1W NGC6853 NGC6720E NGC2392 IC4406 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6564 6590 6732 5012 5476 4694 4865 ------------------------------------------------------------------------------------------------------------------------------------