6131( 3) - 11/20/95 18:36 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6131 Version: 3 Check-in Date: ********** 1.Proposal Title: Brown Dwarf Binaries in the Pleiades ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Richard Jameson Leicester University CoI: Iain Steele Leicester University N CoI: Simon Hodgkin Leicester University N CoI: Nigel Hambly Queens University Belfast N ------------------------------------------------------------------------------------ 6. Abstract Hambly, Hawkins & Jameson (1991, MNRAS, 251, 1) carried out a deep proper motion survey of the Pleiades discovering a large population of low mass stars. Follow-up infrared photometry (Steele, Jameson, & Hambly, 1993, MNRAS, 263, 647) showed that around 20 of the Pleiades objects were good brown dwarf candidates (ie. had M<0.08M_\odot). The Pleiades objects found appear to lie along two sequences in the I,I-K diagram which we believe to be a single star sequence and a binary star sequence. To test this supposition we request high resolution imaging using PC2 of 8 of our brown dwarf candidtes which we believe to lie in binary systems. This will allow us to determine the validity of our photometric test for binarity and hence allow an estimate of the brown dwarf binary fraction to be made. This has important consequnces for the study of the cluster mass function and ultimately for star formation theory. ------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 2] Observations Description ------------------------ We choose to observe a small sample of 8 objects which from the I,I-K diagram have a high probability of binarity. The selection includes our faintest (and reddest) objects, and a representative sample of higher luminosity objects and is listed in Table 1 along with I magnitudes. The obvious camera to use is the Planetary Camera PC2 (to maximize spatial resolution) with the F785LP filter. This filter gives the longest wavelength response consistant with a reasonably short exposure time and thus maximizes the ability to see a `cool' companion. We have calculated exposure times to give 50\ on the central pixel assuming the magnitude of the primary is that of the combined binary. These are shown in Table 1. The maximum exposure required (for the faintest object) is 1800 sec and the minimum 600 sec. Because of the requirement to fit observations within orbits, we calculate that the best use of telescope time is to use the same exposure time for each object of 3 exposures (to provide protection against cosmic ray events and prevent saturation) each of 11 minutes duration. This will, after allowing 12 minutes for aquesition and 3 minutes per readout, completely fill the 54 minute visibility time available at the Pleiades declination for each orbit. These observations will therefore use the available telescope time to its maximium efficiency. They will also give an excellent signal to noise ratio, allowing any distortion of the point spread function to indicate binarity. As an example for a 0.08+0.04 Msun object the secondary would contribute 10\ involving higher mass BDs would obviously be easier to resolve. We also note it may be desirable to move the telescope very slightly between the 11 minute exposures in order to give better sampling of the point spread function. begincenter begintabularllll Object & I magnitude & Exposure Time to & Total Exposure Time, & & fill well to 50\ HHJ3 & 17.4 & 1800 sec & 3*660sec=1980sec, HHJ5 & 17.0 & 1200 sec & 3*660sec=1980sec, HHJ6 & 17.0 & 1200 sec & 3*660sec=1980sec, HHJ10& 16.9 & 1100 sec & 3*660sec=1980sec, HHJ11& 16.8 & 1000 sec & 3*660sec=1980sec, HHJ14& 16.7 & 900 sec & 3*660sec=1980sec, HHJ19& 16.4 & 700 sec & 3*660sec=1980sec, HHJ36& 16.2 & 600 sec & 3*660sec=1980sec, endtabular Table 1. endcenter It would be possible to reduce the number of total orbits required by one by shortening the exposures for HHJ19 and HHJ36 to around 12 minutes and doing the observations in one orbit. This would however lower the senisitvity of the search around these objects. In addition this LaTeX template doesn't allow fractional orbits in the Observing Summary above, so we could not officially propose this split at this stage of the proposal process. In order to prove the technique Figure 2 shows a simulation of a 0.3 arcsec separated 0.08 + 0.04Msun binary (ie. primary 90\ prepared for us by the UK HST support team. The secondary may be easily distinguised. In Figure 3 we plot a crossection though the image. From this is is clear that separations down to 0.15 arcsec will be easily distinguished as separate objects, and down to 0.1 arcsec by asymetry in the PSF. Update We have changed the original program to make one 10min observation with the F702W filter in order to obtain colour information both on the binaries and the deep survey that will result from the 3 wide field cameras. The extra science easily outweighs the very small reduction in signal-to-noise. Real Time Justification ----------------------- None. None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 Pleiades- STAR, Brown Dwarf RA = 3H 45M 53.30S +/- 0.13S, B1950.0 V=21 034850+22443 DEC = 22D 35' 22.2" +/- 2.0" B-V=3 0 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 2 Pleiades- STAR, Brown Dwarf RA = 3H 41M 38.10S +/- 0.13S, B1950.0 V=21 034436+23344 DEC = 23D 25' 18.6" +/- 2.0" B-V=3 2 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 3 Pleiades- STAR, Brown Dwarf RA = 3H 38M 44.40S +/- 0.13S, B1950.0 V=21 034142+23545 DEC = 23D 45' 23.6" +/- 2.0" B-V=3 7 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 4 Pleiades- STAR, Brown Dwarf RA = 3H 45M 37.90S +/- 0.13S, B1950.0 V=21 034835+22534 DEC = 22D 44' 33.4" +/- 2.0" B-V=3 2 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 5 Pleiades- STAR, Brown Dwarf RA = 3H 43M 04.60S +/- 0.13S, B1950.0 V=21 034601+22122 DEC = 22D 03' 10.8" +/- 2.0" B-V=3 9 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 6 Pleiades- STAR, Brown Dwarf RA = 3H 42M 14.40S +/- 0.13S, B1950.0 V=21 034513+23534 DEC = 23D 44' 24.2" +/- 2.0" B-V=3 5 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 7 Pleiades- STAR, Brown Dwarf RA = 3H 34M 15.10S +/- 0.13S, B1950.0 V=21 033716+26293 DEC = 26D 19' 41.5" +/- 2.0" B-V=3 1 I=17.4 E(B-V)=0.1 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 8 Pleiades- STAR, Brown Dwarf RA = 3H 46M 17.70S +/- 0.13S, B1950.0 V=21 034916+23225 DEC = 23D 13' 43.3" +/- 2.0" B-V=3 0 I=17.4 E(B-V)=0.1 6131( 3) - 11/20/95 18:36 - [ 5] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1989.9 0.002 -0.045 0.01 6131( 3) - 11/20/95 18:36 - [ 6] Visit: 01 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034850+2244 30 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034850+2244 30 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034850+2244 30 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 7] Visit: 02 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034436+2334 42 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034436+2334 42 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034436+2334 42 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 8] Visit: 03 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034142+2354 57 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034142+2354 57 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034142+2354 57 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 9] Visit: 04 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034835+2253 42 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034835+2253 42 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034835+2253 42 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 10] Visit: 05 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034601+2212 29 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034601+2212 29 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034601+2212 29 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 11] Visit: 06 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034513+2353 45 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034513+2353 45 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034513+2353 45 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 12] Visit: 07 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 033716+2629 31 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 033716+2629 31 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 033716+2629 31 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 13] Visit: 08 Visit Requirements: PCS MODE Fine 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 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S 034916+2322 50 ------------------------------------------------------------------------------------------------------------------------------------ 2 Pleiades- WFPC2 IMAGE PC1 F785LP 1 550S POSition TARGet 0.483,0.483 034916+2322 50 ------------------------------------------------------------------------------------------------------------------------------------ 3 Pleiades- WFPC2 IMAGE PC1 F702W 1 550S EXPAND END ORBIT 034916+2322 50 ------------------------------------------------------------------------------------------------------------------------------------ 6131( 3) - 11/20/95 18:36 - [ 14] Summary Form for Proposal 6131 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE Fine POSition TARGet 0.483,0.483 EXPAND END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F785LP F702W ------------------------------------------------------------------------------------------------------------------------------------ Target Names Pleiades-034850+224430 Pleiades-034436+233442 Pleiades-034142+235457 Pleiades-034835+225342 Pleiades-034601+221229 Pleiades-034513+235345 Pleiades-033716+262931 Pleiades-034916+232250 ------------------------------------------------------------------------------------------------------------------------------------