8304( 4) - 10/26/99 13:10 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8304 Version: 4 Check-in Date: 26-Oct-1999 13:09:43 1.Proposal Title: Stellar Winds from Central Stars of Young Planetary Nebulae ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Sun Kwok University of Calgary CoI: Kevin Volk University of Calgary Y ------------------------------------------------------------------------------------ 5. Abstract Stellar winds from central stars of planetary nebulae (CSPN) are responsible for driving the dynamical expansion as well as shaping the morphology of planetary nebulae (PN). The stellar winds also remove material from the thin hydrogen atmosphere of the central star, determining whether a PN will stay hydrogen burning throughout its lifetime or will go through an episode of thermal pulse and revert back to the asymptotic giant branch. Wind signatures have been seen in the IUE spectra of a number of evolved PN with high temperature central stars but very little is known about the properties of the stellar winds in young PN when the nebular morphology is being shaped. We request HST time to carry out sensitive UV spectroscopic observations of a number of CSPN. With good S/N spectra, we will be able to fit the line profiles of resonance lines to deduce the mass loss rates and terminal velocities of the stellar winds. We propose to observe 4 young PN selected for their small angular sizes, low temperature sta rs, and high nebular densities. We have chosen a mixture of carbon-rich and oxygen-rich nebulae to see if the wind properties are dependent on atmospheric chemistry. In addition, by fitting the line profiles of some of the atmospheric lines, we can derive the surface gravity and therefore obtain a better determination of the mass and luminosities of the central stars. ------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 2] Observations Description ------------------------ The four objects which we are proposing to observe have been extensively studied at other wavelengths and their general properties are therefore well known. We have carried out model calculations to predict the expected level of UV emission from the stars and from their nebulae. These results were then used as input to the STIS Exposure Time Calculator (hereafter, SETC) software on the STIS WWW pages. We begin the prediction of UV spectrum by first generating the stellar atmospheric models using Kurucz models with effective temperatures matching the hydrogen Zanstra temperatures of the CSPN. These are all near 42000 K. These atmospheric models are then used as inputs into the CLOUDY photoionization code to calculate the nebular spectra, while trying to match the HBeta flux, radio flux density, angular radius, and stellar V magnitude of each of the PN. We assume that the whole stellar flux will be observed while the nebular contribution was scaled to an aperture size of 0.05'' by 0.052'' (the proposed s lit width times the slit length times Delta Lambda/Lambda). For Hb 12 the line to continuum ratio is predicted to be ~0.2 for the strongest lines in the 1250 to 3000 Angstrom wavelength range, while for the other PN the lines are predicted to be much weaker compared to the stellar emission. This is a direct result of the small sky area ``seen'' by each pixel. Hb 12 has a much higher estimated gas density than the other three PN and this produces the higher sky brightness in the lines. As we have taken the smallest reported angular size for Hb 12 it is unlikely that the actual nebular sky brightness will be as large as we have estimated, so there will be no problem with strong emission lines even in this case. Figure 1 below shows the predicted UV spectrum of Hb 12. Similar model spectra of were made for each of the program objects, which were then FTPed to STSCI for use with the SETC. Sources SwSt-1 and BD+303639 were found to be too bright for observation in the G230L m ode but can be observed in G140L m o de. For these objects the SETC was used to find the exposure time to obtain S/N of 50 or larger over the whole G140L wavelength range. The derived exposure times are relatively short, 6 to 8 minutes. With overheads, we can do 2 or 3 exposures in one orbit to improve the S/N of the resultant spectrum. For Hb 12 and Vy 2-2 the extinction is much higher than for the two carbon-rich CSPN. In this case we found that S/N of 40 or higher is expected over most of the G230L wavelength range for Hb 12 after a 4500 second exposure, and that in G140L mode a peak S/N of around 60 should be obtained in the same time. For Vy 2-2 the peak S/N in the G230L wavelength range is predicted to be about 50 for the same exposure time. Thus we have taken 4500 seconds as target exposure time for these two targets. When the slightly different useful times per orbit for the two sources are considered, we find that in 3 orbits the total useful exposure times will be 4440 seconds for Vy 2-2 and 534 0 seconds for Hb 12. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 3] Data Distribution Paper Products: NO Media: 8MM Blocking Factor: 10 Ship To: Kevin Volk, Department of Physics and Astronomy, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4 Ship Via: Email: volk@iras.ucalgary.ca ------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PK001-06D2 STAR, PLANETARY NEBULA RA=18H 16M 12.18S +/- 0.3", DEC= J2000 V = 11.76+/-0.15 CENTRAL STAR -30D 52' 8.10" +/- 0.3", PLATE- B-V = 0.01+/-0.2 ID=060E E(B-V) = 0.35 Comments: Position redetermined from plate 060E; GSC 4011-609 position is off by 0.3" radius; nebular magnitude 10.68 2 PK064+05D1 STAR, PLANETARY NEBULA RA=19H 34M 45.2S +/- 0.2", J2000 V = 12.50+/-0.15 CENTRAL STAR DEC=30D 30' 59.3" +/- 0.2", B-V = -0.54+/-0.2 PLATE-ID=000J E(B-V) = 0.24 Comments: GSC 2655-4032; nebular magnitude 9.02. 3 PK045-02D1 STAR, PLANETARY NEBULA RA=19H 24M 22.23S +/- 0.4", J2000 V = 14.60+/-0.15 CENTRAL STAR DEC=09D 53' 57.01" +/- 0.4", B-V = 0.91+/-0.2 PLATE-ID=02V0 E(B-V) = 1.12 Comments: Position determined from plate 02V0; nebular magnitude 11.60. 4 PK111-02D1 STAR, PLANETARY NEBULA RA=23H 26M 14.80S +/- 0.2", J2000 V = 13.8+/-0.3 CENTRAL STAR DEC=58D 10' 54.9" +/- 0.2", B-V = 0.7+/-0.4 PLATE-ID=02RL E(B-V) = 0.83 Comments: GSC 4011-609; nebular magnitude 11.51. 8304( 4) - 10/26/99 13:10 - [ 5] Visit: 01 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 8 PK001-06D2 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 10 PK001-06D2 STIS/F ACCUM 0.2X0.2 E140M 1425 3 700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 6] Visit: 02 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 18 PK064+05D1 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 PK064+05D1 STIS/F ACCUM 0.2X0.2 E140M 1425 3 700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 7] Visit: 03 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 PK045-02D1 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.7 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 31 PK045-02D1 STIS/N ACCUM 52X0.5 G230L 2376 1 2400 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 33 PK045-02D1 STIS/N ACCUM 52X0.5 G230L 2376 1 2400 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 35 PK045-02D1 STIS/N ACCUM 52X0.5 G230L 2376 1 2400 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 8] Visit: 04 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 PK111-02D1 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.5 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 41 PK111-02D1 STIS/F ACCUM 52X0.5 G140L 1425 1 2500 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 43 PK111-02D1 STIS/F ACCUM 52X0.5 G140L 1425 1 2500 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 45 PK111-02D1 STIS/F ACCUM 52X0.5 G140L 1425 1 2500 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8304( 4) - 10/26/99 13:10 - [ 9] Summary Form for Proposal 8304 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 52X0.5 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M G230L G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names PK001-06D2 PK064+05D1 PK045-02D1 PK111-02D1 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2376 ------------------------------------------------------------------------------------------------------------------------------------