9152( 3) - 03/02/01 18:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9152 Version: 3 Check-in Date: 02-Mar-2001 18:14:16 1.Proposal Title: Circumstellar Gas Around HR 4796A ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Michael Jura University of California - Los Angeles CoI: Ms. Christine Chen University of California, Los Angeles N CoI: Prof. Michael Jura University of California, Los Angeles Y ------------------------------------------------------------------------------------ 5. Abstract We propose to use STIS to study the circumstellar gas around HR 4796A, an 8 Myr old star with a debris disk of ~1.5 * 10^27 g of dust. By searching for circumstellar CO, CI and ZnII, we hope to determine the dust to gas ratio and to constrain the physical conditions in the gas. Is there enough gas to form a Jovian planet; are comets forming? ------------------------------------------------------------------------------------ 9152( 3) - 03/02/01 18:14 - [ 2] Observations Description ------------------------ Since circumstellar gas viewed in absorption has a velocity perpendicular to our line of sight, very high resolution spectra are needed to resolve the extremely narrow circumstellar gas features. To resolve these lines, we propose to observe HR 4796A using the STIS FUV/MAMA and NUV/MAMA echelle spectrograph with the E140H and E230H gratings. The 1150-1700 Angstrom spectral range of the E140H grating should allow us to observe the both the 1560 Angstrom CI multiplet and the CO A-X (0-0, 1-0, 2-0) bands at 1478, 1510 and 1544 Angstrom simultaneously. The 1620-3150 Angstrom spectral range of the E230H grating should allow us to observe the 2026 and 2062 Angstrom ZnII features. HR 4796A was detected with IUE as a bright ultra-violet source with a 1560 Angstrom flux of 3.6*10^-11 erg cm^-2 s^-1 Angstrom^-1 and a 2026 Angstrom flux of 2.0*10^-11 erg cm^-2 s^-1 Angstrom^-1. Note: this flux at 1560 Angstrom from HR 4796A is 20 times brighter than the flux at this wavelength from Beta Pic. We have used the STIS Spectroscopic Exposure Time Calculator to estimate the amount of time needed to obtain a signal-to-noise ratio of 30:1 for a reference wavelengths of 1560 Angstrom and and 2026 Angstrom. With this signal-to-noise level and with a resolution of 114, 000, we can detect absorption features with equivalent widths of ~ 1 mAngstrom. We predict lines much stronger than this. Using the FUV/MAMA and NUV/MAMA echelle spectrograph with the E140H and E230H gratings and the 0.2"*0.09" slit and a flat spectrum normalized to the a point source with HR 4796A's flux density at the specified reference wavelengths gives exposure times of 470 sec and 270 sec for the FUV and NUV observations respectively. The total observatory time needed to observe HR 4796A is ~40.3 minutes- 6 minutes for guide star acquisition, 6 minutes for STIS to acquire the target, 8 mi nutes for STIS FUV/MAMA spectra overheads, 7.8 minutes for the FUV exposure, 8 minutes for STIS NUV/MAMA spectra overheads, and 4.5 minutes for the NUV exposure. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9152( 3) - 03/02/01 18:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD109573 STAR, A0-A3 V-IV, RA=12H 36M 1.11S +/- 0.2", DEC=- J2000 V = 5.78+/-0.02 PROTOPLANETARY DISK 39D 52' 11.2" +/- 0.2" E(B-V) = 0.003+/-0.003 F-CONT(2062)=2.8+/-0.2e-11 F-CONT(2026)=2.8+/-0.2e-11 F-CONT(1544)=3.0+/-0.3e-11 F(1510)=2.0+/-0.2e-11 F(1478)=2.0+/-0.2e-11 B-V = 0.003+/-0.003 TYPE=A0V Coordinate Source: HIPPARCOS_INPUT_CATALOGUE Comments: IUE SWP and LWP spectra of HD109573 are available. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.004857 -0.024 0.01491 9152( 3) - 03/02/01 18:14 - [ 4] 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD109573 STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 1.0 S CD ------------------------------------------------------------------------------------------------------------------------------------ 2 HD109573 STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1.0 S CD K 5ND ------------------------------------------------------------------------------------------------------------------------------------ 3 HD109573 STIS/N ACCUM 0.2X0.0 E230H 2013 1 550 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 4 HD109573 STIS/F ACCUM 0.2X0.0 E140H 1526 1 960 S UV-MAM 9 A ------------------------------------------------------------------------------------------------------------------------------------ 9152( 3) - 03/02/01 18:14 - [ 5] Summary Form for Proposal 9152 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.05ND 0.2X0.09 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E230H E140H ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD109573 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2013 1526 ------------------------------------------------------------------------------------------------------------------------------------