9499( 12) - 05/10/02 08:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9499 Version: 12 Check-in Date: 10-May-2002 08:17:45 1.Proposal Title: Brown Dwarf Binaries as Tests of Substellar Evolution ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Eduardo Martin University of Hawaii CoI: Dan Potter University of Hawaii N CoI: Mike Cushing University of Hawaii N CoI: Dr. Maria Rosa Zapatero Osorio Caltech N CoI: Ben lane Caltech N CoI: Dr. Yakiv Pavlenko Main Astronomical Observatory of Academy N of Sciences of Ukraine ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain STIS spectroscopy of two brown dwarf binaries for which dynamical masses are being obtained by monitoring the orbital motion using ground- based telescopes with adaptive optics. The HST/STIS spectra will allow to study the LiI resonance line at 670.8 nm. The lithium depletion of the members of these binaries will be estimated with the aid of synthetic spectra. These observations will be compared to model predictions of lithium depletion as a function of age and mass, and hence will provide an observational test to the theory of substellar objects. Spin-offs will be the measurement of the strength of Halpha emission, an indicator of chromospheric activity in cool atmospheres, and comparing the shape of the optical continuum with model spectra with different dust opacities. ------------------------------------------------------------------------------------ 9499( 12) - 05/10/02 08:18 - [ 2] Observations Description ------------------------ The STIS/G750M grating and 52x0.2 slit provide a resolution of 2.2 A, which is adequate for measuring the lithium resonance line in the spectra of late-M dwarfs (Marti n et al. 1999b, AJ, 118, 1005). The only information available on the optical brightness of Gl 569B is I=13.9 (Forrest et al. 1988, ApJ, 330, L119). Using the colors of dwarfs with similar spectral type (Leggett et al. 2000, ApJ, 535, 965), we get that Gl 569C has R~17.3. Using the STIS ETC, we estimate that for reaching a S/N ratio of about 40 at 670 nm, the exposure time needed is about 9, 200 s. This is an adequate S/N ratio to determine lithium abundance in late-M type dwarfs. Thus, we request two orbits of HST/STIS for observing Gl 569BC. For HD 130948BC we plan to use the G750L grating. Lithium lines in L dwarfs are generally much stronger (and they are less affected by blending with TiO bands) than in M dwarfs and can be measured with lower resolution (Kirkpatrick et al. 1999, ApJ, 519, 802; Marti n et al. 1999a, AJ, 118, 2466). The near-infrared magnitudes of HD 130948B and C are J, H, K=12.3, 11.8, 11.2 and J, H, K=12.7, 12.2, 11.7, respectively. Uncertainties are +/-0.2 for each passband. We estimate that HD 130948C has R~19.4 using the photometry of Leggett et al. (2000). In 11, 000 s of STIS exposure time, we can obtain a S/N ratio of 36 at 670 nm for HD 130948C, which is sufficient to detect a strong lithium line. Therefore, we request two orbits of HST/STIS for observing HD 130948B and C. Our spectral range for both gratings will include HAlpha and the LiI resonance line at 670.8 nm. We will split the total exposure time in 6 dithered frames to allow for cosmic ray removal and sub-pixel sensitivity corrections. The following analysis will be carried out: 1) rejection of cosmic rays, 2) background subtraction, 3) flat field correction, 4) analysis of the spatial profile to correct for the blended part of the PSF (this is important mainly for Gl 569BC because the separation is only 0.1 arcsec), 5) extraction of one dimensional spectra, 6) wavelength calibration, 7) comparison with model spectra and determination of lithium abundances. Real Time Justification ----------------------- The two binaries are being monitored with adaptive optics in ground-based telescopes. In phase II, we will be able to predict their position angles to within 3 degrees for the following year. We request to schedule the HST/STIS observations soon after one AO run in order to have a very accurate prediction of the position angle. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9499( 12) - 05/10/02 08:18 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GL569A STAR RA=14H 54M 29.24S +/- 0.1", J2000 V = 10.2 DEC=+16D 06' 03.8" +/- 0.1" Coordinate Source: OTHER_SOURCE Comments: Gl569B is separated 5.06 arcsec (PA=28 degrees) from the bright star Gl569A (V=10.2). Use A as the offset reference Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0184 -0.122 0.0 2 GL569B STAR R=5.06", PA=28.00D, FROM 1 J2000 V = 20 Coordinate Source: OTHER_SOURCE Comments: Slit oriented to include both components Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0184 -0.122 0.0 3 HD130948A STAR, BROWN DWARF RA=14H 50M 15.81S +/- 0.1", J2000 V = 5.9 DEC=+23D 54' 42.6" +/- 0.1" Coordinate Source: OTHER_SOURCE Comments: HD 130948B is separated 2.6 arcsec (PA=112 degrees) from the bright star HD 130948A (V=5.9). Use A as the offset reference. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0097 0.0324 0.0 4 HD130948B STAR, BROWN DWARF R=2.6", PA=112.00D, FROM 3 J2000 V = 20 Coordinate Source: OTHER_SOURCE Comments: Slit oriented to include both components Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0097 0.0324 0.0 9499( 12) - 05/10/02 08:18 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 01-May-2002 AND 24-Jul-2002 ORIENT 135D TO 165D ORIENT 315D TO 345D On Hold Comments: Additional Comments: Dates chosen to maximize binary separation. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GL569A STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 2 S CD Comments: Acquisition of primary star. ------------------------------------------------------------------------------------------------------------------------------------ 2 GL569A STIS/C ACCUM 52X0.2 G750L 7751 1 17 S CD Comments: Spectrum of primary star ------------------------------------------------------------------------------------------------------------------------------------ 3 GL569B STIS/C ACCUM F28X50L MIRROR 1 1 S CD P Comments: Image of brown dwarf binary. ------------------------------------------------------------------------------------------------------------------------------------ 4 GL569B STIS/C ACCUM F28X50L MIRROR 1 1 S CD P Comments: Image of brown dwarf binary. ------------------------------------------------------------------------------------------------------------------------------------ 5 GL569B STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=4 1 32 M CD Comments: Brown dwarf binary spectrum covering 530-1020 nm. Separation = 0.09 arcsec. PA 90+\-10. Place both members of the binary on the slit. ------------------------------------------------------------------------------------------------------------------------------------ 6 GL569B STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=4 1 27 M CD Comments: Brown dwarf binary spectrum covering 530-1020 nm ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750L 7751 2 12.5 S CD Comments: Must be taken at the same position as the target. Flat field ------------------------------------------------------------------------------------------------------------------------------------ 9499( 12) - 05/10/02 08:18 - [ 5] Visit: 02 Visit Priority: Visit Requirements: ORIENT 155D TO 159D ORIENT 335D TO 339D 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 HD130948A STIS/C ACQ F25ND3 MIRROR ACQTYPE=POINT 1 0.2 S CD Comments: Acquisition of primary star. ------------------------------------------------------------------------------------------------------------------------------------ 2 HD130948A STIS/C ACCUM 52X0.2 G750L 7751 1 0.5 S CD Comments: Spectrum of primary star. ------------------------------------------------------------------------------------------------------------------------------------ 3 HD130948B STIS/C ACCUM F28X50L MIRROR 1 1 S CD P Comments: Image of brown dwarf binary. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD130948B STIS/C ACCUM F28X50L MIRROR 1 1 S CD P Comments: Image of brown dwarf binary. ------------------------------------------------------------------------------------------------------------------------------------ 5 HD130948B STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=4 1 32 M CD Comments: Brown dwarf binary spectrum covering 530-1020 nm. Separation = 0.13 arcsec. PA=317 deg. Place both members of the binary on the slit. ------------------------------------------------------------------------------------------------------------------------------------ 6 HD130948B STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=4 1 27 M CD Comments: Brown dwarf binary spectrum covering 530-1020 nm ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750L 7751 2 12.5 S CD Comments: Must be taken at the same position as the target. Flat field ------------------------------------------------------------------------------------------------------------------------------------ 9499( 12) - 05/10/02 08:18 - [ 6] Summary Form for Proposal 9499 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 52X0.2 F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-May-2002 AND 24-Jul-2002 ORIENT 135D TO 165D ORIENT 315D TO 345D ORIENT 155D TO 159D ORIENT 335D TO 339D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750L ------------------------------------------------------------------------------------------------------------------------------------ Target Names GL569A GL569B CCDFLAT HD130948A HD130948B ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 7751 ------------------------------------------------------------------------------------------------------------------------------------