The multiplicity properties of brown dwarfs are critical empirical constraints for stellar formation theories, while multiples themselves provide unique opportunities to test evolutionary and atmospheric models as well as examine empirical trends. Brown dwarfs with estimated effective temperatures below 500 K are just now starting to be discovered, filling in the gap between brown dwarfs and Jupiter-like planets (Teff=128K). The Wide-field Infrared Survey Explorer mission (WISE) is uncovering the closest, brightest examples of these objects, making them the best targets for further study. We propose to obtain high resolution images of 13 WISE brown dwarfs with spectral types T8 and later (Teff<700K) using WFC3 in order to search for companions down to effective temperatures of 300K. This proposal compliments our existing NASA Keck LGS-AO program by observing objects for which high resolution imaging is not possible from any ground-based LGS system. The binaries discovered by this program will provide critical information for characterizing the properties of objects at the very bottom of the Main Sequence thus helping to bridge the modeling efforts between brown dwarfs and extrasolar planets. All of our targets are relatively nearby (estimated distances 5–20 pc); however, the overwhelming majority of low-mass binaries (>90%) are tighter than 10–20 AU in physical separation (Allen et al. 2007) implying that the companions for most of our targets would have angular separations <1". High resolution imaging is critical for resolving these systems. Obviously, it is desirable to probe as deeply as possible to discover the coldest brown dwarfs. To do so, however, would be very time consuming and problematic for combining the HST and Keck results for computing the global binary fraction statistics. Thus, we plan our observations such that they are comparable, though deeper, than Keck. Our Keck program has a limiting magnitude of H<23 (30 minute integration), which corresponds to a 310K, 1Gyr object with mass=5MJup located at 10 pc. This same object can be observed to SNR=10 in 7.3 minutes in the F160W filter, easily fitting within a single HST orbit for all of our targets (see Table 1). Since we do not know a priori which targets will have companions, we request observations in more than one filter in order to characterize potential companions. The F110W filter covers both the Y and J bands and offers better SNR than the F125W filter for the cold brown dwarfs that are the focus of this proposal. A 10-sigma observation in this filter requires an additional 3.6 minutes. Both observations can still fit easily within a single orbit (including overheads). When including overheads, and assuming a 50 minute visibility, we find that we will have at least 15 minutes per filter per target. For F110W, this increases the SNR=10 depth by 0.9 mag (this is equivalent to our 310K model at a distance of 15 pc). The gains at F160W are more modest–0.4 mag deeper or a 310K object distance of 12 pc. Figures 2 and 3 show the absolute F160W and F110W magnitudes for the models of Burrows et al. (2003) along with the 10-sigma detection limit for a 900sec integration, 23.7 and 24.8 for F160W and F110W, respectively. In both filters we will probe to effective temperatures colder than WISE 1828+2650, the coldest confirmed brown dwarf. COOL STARS 12 false 0.0 0.0 false false false false SUPPORTED STAR BROWN DWARF T J2000 J2000 J=17.64 STAR BROWN DWARF T J2000 J2000 J=18.61 STAR BROWN DWARF T J2000 J2000 J=20.33 STAR BROWN DWARF T J2000 J2000 J=17.68 STAR BROWN DWARF T J2000 J2000 J=18.39 STAR BROWN DWARF T J2000 J2000 J=17.49 STAR BROWN DWARF T J2000 J2000 J=18.98 STAR BROWN DWARF T J2000 J2000 J<18.5 STAR BROWN DWARF T J2000 J2000 J=17.72 STAR BROWN DWARF T J2000 J2000 J=20.09 STAR BROWN DWARF T J2000 J2000 J=17.48 STAR BROWN DWARF T J2000 J2000 J=17.34 STAR BROWN DWARF T J2000 J2000 J=19.42 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 1 false The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 11:48:26.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2576 :al-overhead-at-end 0 :internal-dur-at-end 576 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3024 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "02" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:00:26.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2576 :al-overhead-at-end 0 :internal-dur-at-end 576 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3013 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "03" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:00:27.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2576 :al-overhead-at-end 0 :internal-dur-at-end 576 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3024 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "04" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 14:10:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1253456 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3141 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. 1349736019000 286.9150298176471 (Tic-Visit :proposal-id 12972 :visit-id "05" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:12:34.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1114176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2776 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3333 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "06" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 14:13:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1253456 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "06" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3141 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "07" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:14:13.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1114176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "07" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2776 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3287 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "08" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:14:35.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1114176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "08" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2776 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3244 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "09" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:17:21.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "09" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2576 :al-overhead-at-end 0 :internal-dur-at-end 576 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3050 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "10" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 14:15:49.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1253456 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "10" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3141 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "11" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 14:17:15.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1253456 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "11" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3141 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3491 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "12" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:21:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1114176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "12" :obset-id "12" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "12" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2776 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12972 :visit-id "13" :proposal-version -1 :trans-version "20120604" :date "03-Jul-2012 12:22:50.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1810544 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12972 :visit-id "13" :obset-id "13" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12972 :visit-id "13" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2576 :al-overhead-at-end 0 :internal-dur-at-end 576 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) true 1 0