6737( 6) - 01/28/97 12:06 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6737 Version: 6 Check-in Date: 28-Jan-1997 12:01:09 1.Proposal Title: Imaging Reflection Nebulosity in Three Post-AGB Objects ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: MARGARET MEIXNER UNIVERSITY OF ILLINOIS CoI: Matthew Bobrowsky CTA INCORPORATED N CoI: Chris Skinner Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract We propose to image the reflection nebulosity of three post- AGB stars, HD56126, HD161796 and HD179821. From our mid- infrared (8-13\m) images, we have determined that all three are surrounded by 2-4" sized dust shells that have a remarkable structure: a geometrically thin, elliptical shell with equatorial density enhancements. The purpose of the HST observations is to image the reflection nebulosity that we expect to be there, but has not yet been observed because ground based resolution is too poor to separate the bright central stars (m_v=7.2-8.3) from the less bright reflection nebulosity. We expect to see a bipolar reflection nebula that is perpendicular to the dusty torus observed in the mid-IR and we may also find large reflection nebula halos and multi-rings indicative of multiple mass loss episodes. We will analyze these data with our mid-IR images using an axially symmetric dust code from which we will derive mass loss rates and pole to equator density ratios. These observations and analysis will provide crucial clues to the physical mechanism that drives the final mass loss stages of AGB stars and that inevitably steers the course of the star's evolution towards the planetary nebula phase. The physical mechanism of stellar mass loss on the AGB is one of the unsolved problems in stellar astrophysics. This AGB mass loss enriches the ISM from which the next generation of stars are born, forming a link between the AGB mass loss problem and the rest of astrophysical phenomena. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our main scientific goal requires the highest angular resolution possible to discriminate between the very bright star and the central reflection nebulosity within 2-4" radius from the star which is predicted from our mid-IR observations of the dust shells. Two other interesting but secondary goals are to detect a close companion and to be detect mutliple rings of nebulosity such as are found in the Egg Nebula. One of the objects, HD179821, has a reported reflection nebulosity in the near-IR of scale size 30". Our observing plan aims to accomodate the main scientific goal by taking numerous short exposures using the PC array of the WFPC2 camera. In order to prevent saturation of the CCD, we plan to observe each of these PPNe with the two medium filters: F410M (Stromgren nu), and F547M (Stromgren y). Real Time Justification ----------------------- Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Margaret Meixner, Dept. of Astronomy, MC-221, University of Illinois, UC, Urbana, IL 61801 Ship Via: Email: meixner@astro.uiuc.edu --3764_2815-77f3_165f-2746_6, ------------------------------------------------------------------------------------ 6737( 6) - 01/28/97 12:06 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD56126 STAR,F3-F9 RA=7H 16M 10.19S +/- 1",DEC=9D J2000 V = 8.2+/-0.5 59' 47.9" +/- 1" B-V = 0.9 E(B-V) = 0.5 Comments: carbon rich post-AGB star with 4" dust shell 2 HD179821 STAR,G III-I RA=19H 13M 58.51S +/- 2",DEC=0D J2000 V = 7.9+/-0.5 7' 31.9" +/- 2" B-V = 1.6 E(B-V) = 1.0 Comments: oxygen rich post-AGB star with 4" dust shell, possibly a supergiant 3 HD161796 STAR,F3-F9 RA=17H 44M 55.43S +/- 1",DEC=50D J2000 V = 7.0+/-0.5 2' 39.9" +/- 1" B-V = 0.5 E(B-V) = 0.2 Comments: oxygen rich post-AGB star with 2" dust shell Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0004 -0.010 0.0 4 HD234478 STAR,G V-IV RA=17H 42M 55.82S +/- J2000 TYPE=G0 0.2S,DEC=50D 14' 16.4" +/- 2" V = 9.52+/-0.41 Comments: calibration star for psf subtraction Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0026 -0.063 0.0 6737( 6) - 01/28/97 12:06 - [ 2] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD56126 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 1.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 2 HD56126 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15, 1 10 S DITHER-LINE-SPACING=0.3413, DITHER-TYPE=LINE, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 3 HD56126 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15, 1 100.0 S DITHER-LINE-SPACING=0.3413, DITHER-TYPE=LINE, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 4 HD56126 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15, 1 0.11 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3, DITHER-TYPE=LINE ------------------------------------------------------------------------------------------------------------------------------------ 5 HD56126 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 2 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6 HD56126 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 30 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6737( 6) - 01/28/97 12:06 - [ 3] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD179821 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 0.11 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD179821 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 4.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 3 HD179821 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 30.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 4 HD179821 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 2.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 5 HD179821 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 40 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6 HD179821 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 220.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6737( 6) - 01/28/97 12:06 - [ 4] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD234478 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 3.0 S DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD234478 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 0.3 S DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD161796 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 0.2 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 4 HD161796 WFPC2 IMAGE PC1-FIX F410M ATD-GAIN=15,DITHER-TYPE=LINE, 1 70 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 5 HD161796 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 0.11 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3 ------------------------------------------------------------------------------------------------------------------------------------ 6 HD161796 WFPC2 IMAGE PC1-FIX F547M ATD-GAIN=15,DITHER-TYPE=LINE, 1 16.0 S DITHER-LINE-SPACING=0.3413, DITHER-LINE-STEPS=3,CLOCKS=YES ------------------------------------------------------------------------------------------------------------------------------------ 6737( 6) - 01/28/97 12:06 - [ 5] Summary Form for Proposal 6737 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=15 DITHER-TYPE=LINE DITHER-LINE-SPACING=0.3413 DITHER-LINE-STEPS=3 CLOCKS=YES DITHER-LINE-STEPS=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F410M F547M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD56126 HD179821 HD234478 HD161796 ------------------------------------------------------------------------------------------------------------------------------------