8209( 8) - 10/26/99 07:04 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8209 Version: 8 Check-in Date: 26-Oct-1999 07:03:34 1.Proposal Title: The Complex Circumstellar Environment of the Massive Contact Binary RY Scuti ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Robert Gehrz University of Minnesota - Twin Cities CoI: Mr. Nathan Smith University of Minnesota N CoI: Dr. Roberta Humphreys University of Minnesota N CoI: Dr. Kris Davidson University of Minnesota N CoI: Dr. Terry J. Jones University of Minnesota N CoI: Dr. Theodore Gull Goddard Space Flight Center N CoI: Dr. Otmar Stahl Landessternwarte, Heidelberg N CoI: Dr. Joachim Krautter Landessternwarte, Heidelberg N ------------------------------------------------------------------------------------ 5. Abstract RY Scuti is a very massive and luminous evolved contact binary system surrounded by an unusual nebula that is only a few arcseconds in extent. We propose to obtain STIS spectra that will spatially resolve the spectrum of the star from its compact nebula for the first time. We also propose to duplicate privious WFPC2 H-Alpha images in order to investigate possible variability of the nebula resulting from eclipses in the binary system. Finally, we propose to image RY Scuti in SIII, which will probe the excitation conditions in the nebula when compared with our H-Alpha image. ------------------------------------------------------------------------------------ 8209( 8) - 10/26/99 07:04 - [ 2] Observations Description ------------------------ We have been granted 2 orbits to complete our observations. The first orbit will consist of long slit spectroscopy with STIS, and the second orbit will consist of imaging with the PC chip of the WFPC2. STIS spectroscopy: We will obtain five exposures with the G750M grating at a central wavelength of 6581 Angstroms. These will be taken with the long slit aperture oriented along the major axis of the nebula at a position angle of PA~58 (or 238) degrees. A range of +/-5 degrees in this position angle is acceptable. We will have one short exposure at the position of the star to acquire an unsaturated spectrum of the central star itself. We have also chosen four postional offsets, two on each side of the star in directions perpendicular to the slit orientation. The offset positions are meant to avoid the bright central star while allowing longer exposure times to sample the fainter nebulosity. We can use previously obtained HST H-Alpha imaging observations to estimate exposure times for the STIS exposures, since we are observing the H-Alpha line. Photometry from our WFPC2 H-Alpha image gives: I_Lambda6563(star) ~ 2.398 * 10^-11 erg cm^-2 s^-1 AA^-1 arcsec^-2 I_Lambda6563(neb) ~ 7.053 * 10^-13 erg cm^-2 s^-1 AA^-1 arcsec^ -2. The sensitivity with grating G750M is Sens^d_Lambda (6600Angstrom) ~ 1.2 * 10^13 (appropriate units), so the count rates with N_spix=2 and N_Lambda pix=2 are C_s(star) ~ 18 counts s^-1 C_s(rings) ~ 612 counts s^-1. For a signal-to- noise ratio of ~75, these result in exposure times of 10 and 320 seconds for the star and nebula, respectively. WFPC2(PC) imaging: We are proposing to duplicate our successful Cycle 7 H-Alpha observations of RY Scuti at a different orbital phase. We will use the filters and exposure times that gave the best results from that series of observations to determine exposure times. The target should be placed in the center of the Planetary Camera CCD chip. Dithered planetary camera exposures in the H-Alpha (F656N) filter will be obtained with exposure times of 120 seconds each (a total of 4 minutes on source). The two separate exposures should be dithered by 2.5 Planetary Camera pixels in x and y. We will also require short 10 second dithered exposures to correct for pixels that will saturate due to the bright central star. Our proposed SIII F953N observations will be very similar to the H-Alpha exposures. We will obtain dithered planetary camera exposures, with exposure times of 10 and 120 seconds. Real Time Justification ----------------------- Since we are searching for phase dependent variability in the nebula, it is vital that the WFPC2 images are obtained at an orbital phase that is significantly different from our previous observations. RY Scuti has a well established ephemeris, with a period of 11.12479 days. For the WFPC2 imaging (visit 2), we have included the visit level special requirement identifying the period and zero phase (here, the zero phase corresponds to the date of our previous images), and we have included the exposure level special requirement which identifies acceptable phases that are significantly different from our previous observations (phases 0.25 to 0.75). Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8209( 8) - 10/26/99 07:04 - [ 3] Data Distribution Paper Products: YES Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8209( 8) - 10/26/99 07:04 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD169515 STAR, Interacting RA=18H 25M 31.48S +/- 0S, DEC=- J2000 V = 9.4+/-0.2 Binary, Supergiant O 12D 41' 24.2" +/- 0" B-V = 1.06 Comments: coordinates are from the Hipparcos Catalogue Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 0.0 0.0 0.0 8209( 8) - 10/26/99 07:04 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 98D TO 108D; ORIENT 278D TO 288D 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 ------------------------------------------------------------------------------------------------------------------------------------ 110 HD169515 STIS/C ACQ F25ND3 MIRROR 1 1 S CD ------------------------------------------------------------------------------------------------------------------------------------ 120 HD169515 STIS/C ACQ/PEA 52X0.1 G750M 6581 1 1 S CD K ------------------------------------------------------------------------------------------------------------------------------------ 130 HD169515 STIS/C ACCUM 52X0.1 G750M 6581 1 10 S CD Comments: spectrum of star ------------------------------------------------------------------------------------------------------------------------------------ 140 HD169515 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2,PATTERN=PERP-TO-SLIT, 1 360 S POS TARG +0.1,+0.0 CD NUM-POS=2,STEP-SIZE=0.15, PATTERN-DIRECTION=PLUS Comments: spectrum of rings, positive offset ------------------------------------------------------------------------------------------------------------------------------------ 150 HD169515 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2,PATTERN=PERP-TO-SLIT, 1 360 S POS TARG -0.1,+0.0 CD NUM-POS=2,STEP-SIZE=0.15, PATTERN-DIRECTION=MINUS Comments: spectrum of rings, negative offset ------------------------------------------------------------------------------------------------------------------------------------ 8209( 8) - 10/26/99 07:04 - [ 6] Visit: 02 Visit Priority: Visit Requirements: PERIOD 11.12479D AND ZERO-PHASE JD2450601 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 ------------------------------------------------------------------------------------------------------------------------------------ 220 HD169515 WFPC2 IMAGE PC1 F656N DITHER-TYPE=LINE, 1 10 S PHASE 0.25 TO 0.75 DITHER-LINE-SPACING=0.1609 Comments: dither spacing is 2.5, 2.5 pixels; smaller than default value. this will be used for all dithered observations in this visit. ------------------------------------------------------------------------------------------------------------------------------------ 230 HD169515 WFPC2 IMAGE PC1 F656N DITHER-TYPE=LINE, 1 120 S PHASE 0.25 TO 0.75 DITHER-LINE-SPACING=0.1609, CLOCKS=YES Comments: star will saturate. ------------------------------------------------------------------------------------------------------------------------------------ 250 HD169515 WFPC2 IMAGE PC1 F953N DITHER-TYPE=LINE, 1 10 S PHASE 0.25 TO 0.75 DITHER-LINE-SPACING=0.1609 ------------------------------------------------------------------------------------------------------------------------------------ 260 HD169515 WFPC2 IMAGE PC1 F953N DITHER-TYPE=LINE, 1 120 S PHASE 0.25 TO 0.75 DITHER-LINE-SPACING=0.1609, CLOCKS=YES Comments: star will saturate ------------------------------------------------------------------------------------------------------------------------------------ 8209( 8) - 10/26/99 07:04 - [ 7] Summary Form for Proposal 8209 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 52X0.1 PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 PATTERN=PERP-TO-SLIT NUM-POS=2 STEP-SIZE=0.15 PATTERN-DIRECTION=PLUS PATTERN-DIRECTION=MINUS DITHER-LINE-SPACING=0.1609 CLOCKS=YES DITHER-TYPE=LINE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 98D TO 108D; ORIENT 278D TO 288D POS TARG +0.1,+0.0 POS TARG -0.1,+0.0 PERIOD 11.12479D AND ZERO-PHASE JD2450601 PHASE 0.25 TO 0.75 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M F656N F953N ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD169515 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6581 ------------------------------------------------------------------------------------------------------------------------------------