8205( 7) - 08/31/01 17:27 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8205 Version: 7 Check-in Date: 31-Aug-2001 17:25:51 1.Proposal Title: UV Spectroscopy of Infalling Cometary Material in Solar-Type Pre-Main Sequence Stars ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Carol Grady Eureka Scientific Inc. CoI: Dr. Catherine Imhoff Space Telescope Science Institute N CoI: Dr. Dolf de Winter Instituto de Astrofisica de Canarias N CoI: Dr. Carlos Eiroa Dpto. Fisica Teoretical, Universidad N Autonoma de Madrid CoI: Dr. Michael Sitko University of Cincinnati N CoI: Dr. Vladimir Grinin Crimean Astrophysical Observatory N CoI: Dr. Andreas Quirrenbach University of California, San Diego N CoI: Dr. Thomas Henning Astrophysical Institute & Univ. N Observatory, Jena ------------------------------------------------------------------------------------ 5. Abstract Models for the formation of the Solar System predict that an intermediate stage in planet formation was the assembly of material in the disk into planetesimals, and that this should be a common step in the evolution of planetary systems. Planetesimals are difficult to detect directly except by activity in renewing the small grain population in mature (e.g. t>100 Myr) planetary disks, or by the presence of cometary activity. Cometary activity can provide a marker for the presence of planetesimals in younger systems where much of the dust is a remnant of the original protoplanetary disk. The presence of such cometary activity has been inferred from redshifted absorption features in the optical & UV spectra of Beta Pic and a large number of younger, intermediate-mass pre- Main Sequence stars. However, if the interpretation of these features as the aggregate comae of swarms of star- grazing bodies is correct, similar activity must be present and remotely detectable in the disk s of young, solar analogs. We propose using HST STIS to obtain the first UV spectroscopic observations of infall activity in the disks of young, Solar- type stars, supplemented by a comparison intermediate- mass star. The data will be used to determine whether infall activity around young Suns evolves on the same time scale as for disks around more massive and luminous stars. ------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 2] Observations Description ------------------------ Acquisition exposure times were selected using the exposure time calculator and broad-band optical data, following the approach given in program 7718. A 30 second exposure give S/N=84.7 for the nominal flux level. Both sources are highly photometrically variable. Under the historical minimum light conditions, our exposure time will yield S/N>=40, suitable for target acquisition. At maximum light (10x enhancement in flux), the peak flux will be under 30, 000e for T Cha, and under 40, 000 electrons. UV Exposure estimates for the RY Lup observations are based on archival IUE observations obtained approximately 1 magnitude below optical maximum, which is the highest probability light level for the STIS observations. These data suggest that at this level, a 4800 second exposure in G140L will yield S/N=30 at 1350 A, and a 1600 second exposure in G230L will yield S/N=55.5. At minimum light, the corresponding S/N would be 25.5 for the G230L mode, and in excess of 15 (there is scatt er ed light in the FUV from the disk, which limits the depth of minima at those wavelengths). The RY Lup minimum light conditions are likely to apply to T Cha near maximum light. We are currently proposing a G230MB observation for RY Lup centered at 2794 A. Using the exposure estimator, a 7200s exposure will yield S/N=27.7 at 2836 A, ensuring a usable (S/N>13.9) spectrum under minimum light conditions. The extent to which this mode is subject to straylight contamination due to red -leak from the CCD is apparently not currently well-established by the STScI's calibration program. We request that such calibrations be obtained prior to the time of our observation. In the event that the optical colors of our program stars are too red for this mode we will explore acquisition of either G230M or the cross-dispersed MAMA mode (2.7x4 in the GTO notation) spectra. The most significant source of sky background, and the dominant FUV emission line will be geocoronal Lyman-alpha. From the ST IS handbook, the high (day side) background level will be 3 .7E-3 c/pixel/s corresponding to a global count rate for the 52x0.2" aperture of 15 c/s, well below the local count rate threshold. The night side geocoronal contribution will be an order of magnitude smaller. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- We wish to have observations coordinated with ground-based observing campaigns, including synoptic photometric observations (lead by co-I Sitko), optical polarimetric observations, and optical spectroscopy. ------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: Ms. Jennifer Sandoval, Code 681, NASA/GSFC, Greenbelt MD 20771 Ship Via: Email: stisdata@stis.gsfc.nasa.gov ------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RY-LUP STAR, T TAURI STAR, RA=15H 59M 28.4S +/- 0.003", 2000 TYPE=GOVE EMISSION LINE STAR, DEC=-40D 21' 51.1" +/- 0.003" F(1600)=3e-14 PROTOPLANETARY DISK V = 11.65+/-1.75 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.001 -0.022 0.00926 2 T-CHA STAR, T TAURI STAR, RA=11H 57M 13.66S +/- 0.003", 2000 TYPE=G2 PROTOPLANETARY DISK, DEC=-79D 21' 31.5" +/- 0.003" V = 11.6+/-1.6 JET Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1991.25 -0.0143 -0.00987 0.015 8205( 7) - 08/31/01 17:27 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 88D TO 98D ORIENT 268D TO 278D 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 RY-LUP STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 30 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 20 RY-LUP STIS/F ACCUM 52X0.2 G140L 1425 3 1075 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 25 RY-LUP STIS/N ACCUM 52X0.2 G230L 2376 2 600 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 RY-LUP STIS/F ACCUM 52X2 G140L 1425 2 600 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 35 RY-LUP STIS/N ACCUM 52X2 G230L 2376 1 500 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 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 RY-LUP STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 30 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 20 RY-LUP STIS/C ACCUM 52X0.2 G230MB 2794 CR-SPLIT=3 1 3600 S CD ------------------------------------------------------------------------------------------------------------------------------------ 40 RY-LUP STIS/C ACCUM 52X0.2 G230MB 2794 CR-SPLIT=3 1 3600 S CD ------------------------------------------------------------------------------------------------------------------------------------ 50 RY-LUP STIS/C ACCUM 52X0.2 G230MB 2976 CR-SPLIT=4 1 2000 S CD ------------------------------------------------------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 7] Visit: 03 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Observation is to be coordinated with ground-based supporting observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 T-CHA STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 30 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 20 T-CHA STIS/N ACCUM 52X0.2 G230L 2376 2 1200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 T-CHA STIS/F ACCUM 52X0.2 G140L 1425 3 1200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 T-CHA STIS/F ACCUM 52X0.2 G140L 1425 2 1200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 T-CHA STIS/N ACCUM 52X2 G230L 2376 1 1400 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 60 T-CHA STIS/F ACCUM 52X2 G140L 1425 1 1400 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 T-CHA STIS/C ACQ F28X50O MIRROR ACQTYPE=POINT 1 30 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 20 T-CHA STIS/C ACCUM 52X0.2 G230MB 2794 CR-SPLIT=3 1 3900 S CD ------------------------------------------------------------------------------------------------------------------------------------ 70 T-CHA STIS/C ACCUM 52X0.2 G230MB 2794 CR-SPLIT=4 1 4000 S CD ------------------------------------------------------------------------------------------------------------------------------------ 80 T-CHA STIS/C ACCUM 52X0.2 G230MB 2794 CR-SPLIT=4 1 4000 S CD ------------------------------------------------------------------------------------------------------------------------------------ 8205( 7) - 08/31/01 17:27 - [ 9] Summary Form for Proposal 8205 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 52X0.2 52X2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=3 CR-SPLIT=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 88D TO 98D ORIENT 268D TO 278D SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L G230L G230MB ------------------------------------------------------------------------------------------------------------------------------------ Target Names RY-LUP T-CHA ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2376 2794 2976 ------------------------------------------------------------------------------------------------------------------------------------