Stellar feedback - the return of mass and energy from star formation to the interstellar medium - is one of the primary engines of galaxy evolution. Yet, the observational canvass of feedback is incomplete. We propose to investigate this fundamental aspect of star formation on one local actively star-forming galaxy, He2-10, selected to occupy an unexplored niche in the key parameter space of stellar mass. The WFPC2 narrow-band observations in the light of H-beta, [OIII], H-alpha, and [SII] will: (1) discriminate the feedback-induced shock fronts from the photoionized regions; (2) map, and provide a complete census of, the shocks inside and around the starburst regions; and (3) measure the energy budget of the star-formation-produced shocks. These observations, joined by our previous data and studies on starbursts, will yield: (1) the efficiency of the feedback, i.e. the fraction of the star formation's mechanical energy transported out of the starburst volume rather than radiated away, in the dual-parameter space of host's stellar mass and star formation intensity; (2) the conditions under which feedback morphs from a localized process to a galactic scale mechanism. The high angular resolution of HST is crucial for separating the spatially narrow shock fronts (~10 pc=0.2" at 10 Mpc) from the more extended photoionization fronts. This project will provide the most comprehensive quantitative foundation of stellar feedback and a gauge for determining the role of feedback in the energetics, structure and star formation history of galaxies.

WFPC2 F487N, F502N, F658N, and F673N narrow-band images, centered on the emission lines H-beta, [OIII], H-alpha, and [SII] doublet, together with medium/broad band images in F547M and F814W for probing the underlying stellar continuum, will be obtained for the starburst galaxy Henize 2-10. The images will be centered in the WF3 chip, which can accomodate the entire starburst region plus surrounding areas. 4 dithered images, using the WFPC2-BOX pattern, will be obtained in each filter, for cosmic ray and hot pixel removal. Total exposure times will be: 920 sec in F547M, 640 sec in F814W, 4400 sec in F487N, 5200 sec in F502N, 2000 sec in F658N, and 3200 sec in F673N. ISM IN EXTERNAL GALAXIES 12 false 0.0 false false false false false false SUPPORTED GALAXY SHOCK FRONT STARBURST ESO495-G021 J2000 08 36 15.2000 -26 24 34.00 J2000 WFPC2 Imaging No F487N WFPC2 Imaging No F673N WFPC2 Imaging No F547M WFPC2 Imaging No F814W WFPC2 Imaging No F658N WFPC2 Imaging No F673N POS-TARG DITHER 0.559017 LINE 0.559017 false false 143.130096 4 26.56505 WFPC2-BOX 1 false (Tic-Visit :proposal-id 11146 :visit-id "01" :proposal-version -1 :trans-version "20070325" :date "08-May-2007 14:39:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 537792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11146 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11146 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 100 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 100 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 100 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "01" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 4 0 (Tic-Visit :proposal-id 11146 :visit-id "02" :proposal-version -1 :trans-version "20070325" :date "08-May-2007 14:49:51.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 537792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11146 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11146 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "02" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "02" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11146 :visit-id "02" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 4 0 (Tic-Visit :proposal-id 11146 :visit-id "A2" :proposal-version -1 :trans-version "20070709" :date "02-Jan-2008 07:14:14.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 134448 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11146 :visit-id "A2" :obset-id "A2" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11146 :visit-id "A2" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 1 0