9466( 3) - 04/02/02 11:00 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9466 Version: 3 Check-in Date: 02-Apr-2002 11:00:04 1.Proposal Title: SBS 1150+599: A Population III Planetary Nebula? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Peter Garnavich University of Notre Dame CoI: Dr. Howard E. Bond Space Telescope Science Institute N CoI: Dr. Alberto Noriega-Crespo IPAC N CoI: Mr. Jason Quinn University of Notre Dame N ------------------------------------------------------------------------------------ 5. Abstract SBS 1150+599 is a puzzling emission-line object. Optical spectra reveal only strong Balmer, He II and Ne V lines, along with a hot, featureless continuum. We have recently partially resolved the HAlpha emission in a ground-based image, and believe the object to be a new halo planetary nebula, one of only handful known in the Milky Way. If correct, its lack of significant O III and other forbidden emission means that SBS 1150+599 has the lowest metallicity of any known planetary nebula. Our estimate of the oxygen abundance places it 40 times lower than that of K 648 in the globular cluster M15, the previous record holder, and would make it one of the most metal-poor objects in the Galaxy. We propose obtaining ACS images of SBS 1150+599 to confirm that it is a planetary nebula and to determine its morphology. Planetary nebulae in old populations may occur due to binary-star merging, and the morphology may test this hypothesis. We will also study the UV spectrum of SBS 1150+599 using STIS to confirm the O/H value and estimate carbon and nitrogen abundances unobtainable in the optical. ------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 2] Observations Description ------------------------ We propose to obtain narrow-band images of SBS 1150+599 using the ACS/HRC. Exposures in F334N (Ne V) and F658N (HAlpha) will span the available range of excitation. Ne V is the only bright metal line available and it is important to see how the metals are distributed as this will improve the spectral models. The pixel scale of the HRC and low sensitivity at 340 nm means that 2.5 orbits are needed to reach an average S/N=3 per pixel (this assumes that the observed flux is spread evenly over the 3'' diameter of the nebula, so any condensations will result in much higher S/N). One half an orbit will be used to get an HAlpha image. The 3'' width of the PN will easily fit in the 26'' FOV of HRC. The HST narrow filters are able to accommodate the 200 km/s blue shift of the lines. We also propose to obtain STIS/MAMA spectra of SBS 1150+599 which will provide abundance estimates of carbon and nitrogen as well as improve our measurement of the oxygen abundance. We will use the 0.5'' slit to maximize the flux entering the spectrograph while minimizing line blending. Because of the low metal abundance in this object we will still require 5 orbits to get useful spectra in the G140L grating and 3 orbits in the G230L. Fortunately, the SBS 1150+599 often falls in the CVZ so these observations can be very efficient. The reddening toward SBS 1150+599 is only E(B-V)=0.031 and its systemic velocity is 200 km/s, so interstellar gas will not absorb the nebular lines in the UV. We will observe at a roll angle that places the slit across the brightest regions of the nebula and include the central star. The brightness of the central star is only V=18.0, but it is very hot and the extinction is low, so the UV spectrum will have excellent signal. We will observe in the time-tag MAMA mode which will allow us flexibility in binning the light curve. Real Time Justification ----------------------- At a declination of +59.5^degrees, SBS 1150+599 falls in the CVZ seven times a year for a total of 293 orbits. Since we require long STIS integrations, use of the CVZ is very efficient and the longer observing time per orbit reduces the number of total orbits required. None Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SBS1150+599 STAR, PLANETARY NEBULA RA=11H 53M 24.74S +/- 0.5", J2000 V = 18.0+/-0.3 CENTRAL STAR, ISM, DEC=59D 39' 56.82" +/- 0.5", PLANETARY NEBULA PLATE-ID=01QZ Coordinate Source: GSC_SURVEY_PLATE Comments: Nebula is 3" in diameter with bright condensations at PA=113.3 degrees 9466( 3) - 04/02/02 11:00 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-HRC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.150 Coordinate_Frame POS-TARG Pattern_Orient 19.89 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 5 Point_Spacing 0.125 Coordinate_Frame POS-TARG Pattern_Orient 90 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 5] Visit: 01 Visit Priority: Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 SBS1150+599 ACS/HR ACCUM HRC F344N CR-SPLIT=3 1 3000 S PATTERN 1 10 C ------------------------------------------------------------------------------------------------------------------------------------ 50 SBS1150+599 ACS/HR ACCUM HRC F658N CR-SPLIT=2 1 870 S PATTERN 1 50 C ------------------------------------------------------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 6] Visit: 02 Visit Priority: Visit Requirements: CVZ ORIENT 148D TO 168D 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 SBS1150+599 STIS/C ACQ 50CCD MIRROR 1 2.0 S CD ------------------------------------------------------------------------------------------------------------------------------------ 10 SBS1150+599 STIS/N ACCUM 52X0.5 G230L 2376 3 950 S POS TARG 0,-0.250 PATTERN UV-MAM 2 10 A ------------------------------------------------------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 7] Visit: 03 Visit Priority: Visit Requirements: CVZ ORIENT 148D TO 168D SAME ORIENT AS 02 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 SBS1150+599 STIS/C ACQ 50CCD MIRROR 1 2.0 S CD ------------------------------------------------------------------------------------------------------------------------------------ 10 SBS1150+599 STIS/C ACCUM 52X0.5 G430L 4300 CR-SPLIT=2 1 600 S CD ------------------------------------------------------------------------------------------------------------------------------------ 20 SBS1150+599 STIS/F ACCUM 52X0.5 G140L 1425 5 935 S POS TARG 0,-0.250 PATTERN UV-MAM 2 20 A ------------------------------------------------------------------------------------------------------------------------------------ 9466( 3) - 04/02/02 11:00 - [ 8] Summary Form for Proposal 9466 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC 50CCD 52X0.5 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC STIS/CCD STIS/NUV-MAMA STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=3 CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ PATTERN 1 10 PATTERN 1 50 CVZ ORIENT 148D TO 168D POS TARG 0,-0.250 PATTERN 2 10 CVZ ORIENT 148D TO 168D SAME ORIENT AS 02 POS TARG 0,-0.250 PATTERN 2 20 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F344N F658N MIRROR G230L G430L G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names SBS1150+599 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2376 4300 1425 ------------------------------------------------------------------------------------------------------------------------------------