We propose to obtain HST/ACS F606W coronagraphic imaging of two young (10--50 Myr), nearby (25--55 pc) M dwarfs to resolve their debris disks in scattered light. Little is known about debris disks around M dwarfs, as very few examples are known and only one, the AU Mic debris disk, has been spatially resolved thus far. IR/sub-mm photometry of our targets indicate large quantities of exceptionally cold dust, comparable to the prototype AU Mic system, and make them excellent candidates for resolved studies with physical resolutions of 1-2 AU. HST/ACS provides an excellent capability for detection of disks in scattered light. Modeling the disk images will allow us to quantify the radial and vertical structure and to search for disk sub-structure, a potential probe of the planet formation process in these young systems. Our program can expand the census of young resolved debris disks, of which very few are currently known. M dwarfs have been largely over-looked in myriad imaging searches: our program will complement the many current programs focusing on the higher-mass AFGK stars. Because our targets belong to nearby young moving groups with known resolved disks around higher mass stars, a key potential outcome of our program is comparative study of coeval debris disks over a range of stellar masses.

We will use the ACS/HRC coronagraph with the 0.9'' mask to resolve disks around two M dwarfs. For each target and PSF reference star we will take short, non-coronagraphic, and long (one orbit each) coronagraphic exposures. The PSF reference star is a star of the same spectral type but brighter and as spatially close to the target as possible. The coronagraphic observations will be done using the F606W filter, which is well calibrated and has been used in the past for this kind of work. Target acquisition is done in a narrow-band filter to avoid saturation. For each target, two orbits are necessary, one for the target and the other for the PSF reference. ISM AND CIRCUMSTELLAR MATTER 12 false 0.0 false false false false false false SUPPORTED STAR M V-IV Hipparcos Coordinates V=10.1 B-V=1.37 (Ground-based) J2000 04 59 34.8328 +01 47 0.68 J2000 STAR M V-IV Tycho Coordinates V=11.65 B-V=1.46 (ground based) J2000 10 42 30.3000 -33 40 17.00 J2000 STAR M V-IV Hipparcos Coordinates V=10 B-V=1.465 J2000 00 00 0.0000 +00 00 0.00 J2000 STAR M V-IV Hipparcos Coordinates V=8.17 No ground based or other photometric measurements. Bt-Vt=1.538 J2000 00 00 0.0000 +00 00 0.00 J2000 ACS/HRC Imaging No No F606W ACS/HRC Imaging No No F660N ACS/HRC Imaging Yes No F606W ACS/HRC Imaging No No F660N ACS/HRC Imaging Yes No F606W ACS/HRC Imaging No No F606W ACS/HRC Imaging No No F606W ACS/HRC Imaging No No F660N ACS/HRC Imaging Yes No F606W ACS/HRC Imaging No No F660N ACS/HRC Imaging Yes No F606W ACS/HRC Imaging No No F606W (Tic-Visit :proposal-id 10828 :visit-id "01" :proposal-version -1 :trans-version "20060322" :date "28-Apr-2006 13:16:11.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10828 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10828 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2775 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10828 :visit-id "02" :proposal-version -1 :trans-version "20060322" :date "11-Aug-2006 13:43:20.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10828 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10828 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2774 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10828 :visit-id "03" :proposal-version -1 :trans-version "20060322" :date "11-Aug-2006 13:43:30.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10828 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10828 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2795 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3152 :pcs-gap 0 ) false 1 0 (Tic-Visit :proposal-id 10828 :visit-id "04" :proposal-version -1 :trans-version "20060322" :date "11-Aug-2006 13:43:35.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 111104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 10828 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 10828 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2802 :al-overhead-at-end 0 :internal-dur-at-end 160 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3159 :pcs-gap 0 ) false 1 0