6693( 9) - 06/19/97 17:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6693 Version: 9 Check-in Date: 19-Jun-1997 15:59:35 1.Proposal Title: Circumstellar Nebulae as Fossil Records of the Mass Loss History in Luminous Blue Variables ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ANTONELLA NOTA SPACE TELESCOPE SCIENCE INSTITUTE CoI: Mark Clampin Space Telescope Science Institute N CoI: Guillermo Garcia-Segura Instituto de Astronom'\\i a-UNAM N CoI: Norbert Langer Max Planck Institut, Munich N CoI: Claus Leitherer Space Telescope Science Institute N CoI: Mario Livio Space Telescope Science Institute N CoI: Anna Pasquali Space Telescope Science Institute N CoI: Regina Schulte-Ladbeck University of Pittsburgh N ------------------------------------------------------------------------------------ 6. Abstract We propose to exploit the unique spatial resolution of HST to perform a detailed imaging study of three nebulae around Galactic Luminous Blue Variables, selected on the basis of their different morphologies and physical characteristics. The observations will be performed in selected lines and in the continuum, in order to derive a complete picture of the ionized gas and dust distribution within the nebulae, at the same high resolution. Extensive ground based coronographic observations of these nebulae suggest that an interacting wind scenario can explain most of the morphologies observed, both on large and small spatial scales. We want to compare the high resolution HST images with the predictions of multidimensional, hydrodynamical models to quantitatively establish 1) the wind velocity and mass loss properties of the pre outburst phase, and 2) the duration of the pre outburst phase. The large scale nebular structure will provide information on the LBV outburst mechanism and related intervening factors (rotation, binarity). The small scale features will provide information on the local instabilities, such as anisotropies of the wind. An experiment conducted on recent HST images of the galactic LBV AG Carinae has proven the method is effective and has demonstrated its potential as a diagnostic tool, to empirically investigate the mass loss history and, thereby, the evolutionary history of the central star. ------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 2] Observations Description ------------------------ We propose to use the PC to obtain high spatial resolution images of the circumstellar nebulae around three galactic Luminous Blue Variables, with the objective of characterizing both their large and small scale structure. The need for the PC is justified by several reasons: 1) the high angular resolution (0.046''/pixel) of the Point Spread Function, 2) the relatively large field of view (35''*35''); 3) the good spectral response at the red wavelengths of interest; 4) the suitability of the CCD cameras for observations requiring high dynamic range, as WFPC2 CCDs have MPP architecture (see WFPC2 Handbook, 1995), and, therefore, limited blooming on saturated stars. , For each of the three nebulae, we will take PC images in the following filters: 547M - V Continuum, F656N - HAlpha, F658N - NII. Our observational strategy is to obtain two images of each object/filter combination, to properly correct for cosmic rays. The exposure time for each of the two images has been calculated in order to achieve a S/N of 10 in the nebular region, while saturating the central object. On the basis of the WWW WFPC2 exposure time estimator and the WFPC2 handbook, using the PC camera and the F547M filter for a star with V = 7 and surface brightness in the nebula of ~eq 18 magnitudes/square arcsecs, two exposures of 300 secs, for each filter, will achieve a S/N per pixel of 10. For the HAlpha emission, assuming a typical line flux of 6times10^-14 ergs/sec/cm^2/arcsec^2, we derive a S/N per pixel of 10 for two 400 sec exposures. The NII emission is comparable to HAlpha and therefore a similar exposure time will be used, with a total of 36 minutes for each target. Including the Guide Star Acquisitions and the exposure overheads, the complete set of observations for each target requires approximately one orbit. We are aware that the bright central stars will saturate columns contained within a radius of approximately 0.3 arcsecs. For all exposures we will operate the CCDs with the serial clocks running in order to remove excess charge from saturated columns and prevent charge spreading to adjacent columns. This strategy has already proven successful, allowing us to obtain the excellent image of AG Carinae that is shown in Figure 1. In addition, we are interested in the nebular features as close as possible to the central star, and therefore, we request to repeat the observation sequence for each target a second time, after at least two months, in order to apply a roll deconvolution technique. After two months or more the spacrecraft, and therefore the Point Spread Function, will be rotated by at least 60 degrees with respect to the sky and to the object observed. This technique will allow us to distinguish PSF artifacts from nebular features in the region 1-5'' from the central star, where we cannot observe from the ground. The total time required amounts therefore to 6 orbits. Real Time Justification ----------------------- The two sets of observations must be spaced in time by at least 2 months in order to allow a roll difference of 60 degrees or more. No supporting observations will be needed for this program. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD168625 STAR,EMISSION LINE RA=18H 21M 19.69S +/- 0.5S, DEC= J2000 V = 8.41 STAR,LUMINOUS BLUE -16D 22' 26.5" +/- 0.5", PLATE- B-V = +1.46 VARIABLE ID=064B 2 HR-CARINAE STAR,EMISSION LINE RA=10H 22M 54.19S +/- 0.5S, DEC= J2000 V = 8.55 STAR,LUMINOUS BLUE -59D 37' 28.3"+/- 0.5", PLATE- B-V = +0.88 VARIABLE ID=0686 6693( 9) - 06/19/97 17:18 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 100 HD168625 WFPC2 IMAGE PC1 F547M CLOCKS=YES,ATD-GAIN=15 2 200 S ------------------------------------------------------------------------------------------------------------------------------------ 101 HD168625 WFPC2 IMAGE PC1 F656N CLOCKS=YES,ATD-GAIN=15 3 500 S ------------------------------------------------------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 6] Visit: 02 Visit Requirements: AFTER 1 BY 66D TO 73D 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 ------------------------------------------------------------------------------------------------------------------------------------ 200 HD168625 WFPC2 IMAGE PC1 F547M CLOCKS=YES,ATD-GAIN=15 2 200 S ------------------------------------------------------------------------------------------------------------------------------------ 201 HD168625 WFPC2 IMAGE PC1 F656N CLOCKS=YES,ATD-GAIN=15 3 500 S ------------------------------------------------------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 7] Visit: 03 Visit Requirements: ORIENT 180D TO 180D 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 ------------------------------------------------------------------------------------------------------------------------------------ 302 HR-CARINAE WFPC2 IMAGE PC1 F547M CLOCKS=YES 2 120 S ------------------------------------------------------------------------------------------------------------------------------------ 303 HR-CARINAE WFPC2 IMAGE PC1 F656N CLOCKS=YES 3 600 S ------------------------------------------------------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 8] Visit: 04 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 ------------------------------------------------------------------------------------------------------------------------------------ 402 HR-CARINAE WFPC2 IMAGE PC1 F547M CLOCKS=YES,ATD-GAIN=15 2 120 S ------------------------------------------------------------------------------------------------------------------------------------ 403 HR-CARINAE WFPC2 IMAGE PC1 F656N CLOCKS=YES,ATD-GAIN=15 3 600 S ------------------------------------------------------------------------------------------------------------------------------------ 6693( 9) - 06/19/97 17:18 - [ 9] Summary Form for Proposal 6693 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CLOCKS=YES ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 1 BY 66D TO 73D ORIENT 180D TO 180D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F547M F656N ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD168625 HR-CARINAE ------------------------------------------------------------------------------------------------------------------------------------