Stellar feedback is one of the most important engines of galaxy formation and evolution. However, the observational constraints are not yet established. We propose to investigate this problem by observing 2 nearby star-forming galaxies, selected to fill an unexplored niche in the key 2-dimensional parameter space of host galaxy’s stellar mass and star formation rate density. From the WFC3 narrow-band observations in the light of H-alpha, H-beta, [OIII], and [SII], we will : (1) produce the line diagnostic diagrams, [O III](5007)/H-beta vs. [S II](6716+6731)/H-alpha, (2) discriminate the feedback-driven shock-ionized component from the ionized gas, (3) measure the energy budget of the shocks from star forming feedback. Those observations, joined by our previous data and studies on nearby starburst galaxies, will yield the efficiency of the feedback, i.e. the fraction of the star formation’s mechanical energy transported out of the starburst site rather than radiated away, as a function of both stellar mass and star formation rate intensity. The high angular resolution of HST is crucial for separating the shock fronts (~10pc = 0.2’’ at 10 Mpc) from the photo-ionized regions. This project will provide the quantitative foundation of stellar feedback and a gauge for determining the role of feedback in the energetics, structure, and star formation history of galaxies.

The two starburst galaxies, MRK-178 and NGC4861, will be observed using the four narrow-band filters, F487N, F502N, F657N(or F658N), and F673N and two broad and medium filters, F814W and F547M. The 4 orbits are assigned to each galaxy. The observing strategy is the same with the WFC3 ERS 1, GO11360. The field of view of WFC3/UVIS is enough to cover our target, the starburst region of each galaxy. The observed H-apha wavelenghs are 6568.5 for Mrk178 and 6581.3 for NGC4861, which are fit within the F657N and F658N throughputs. ISM IN EXTERNAL GALAXIES 6 false 0.0 0.0 false false false false SUPPORTED GALAXY EMISSION LINE NEBULA STAR FORMING REGION STARBURST J2000 J2000 GALAXY EMISSION LINE NEBULA STAR FORMING REGION STARBURST J2000 J2000 WFC3/UVIS Imaging No No F487N WFC3/UVIS Imaging No No F502N WFC3/UVIS Imaging No No F547M WFC3/UVIS Imaging No No F656N WFC3/UVIS Imaging No No F673N WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F487N WFC3/UVIS Imaging No No F502N WFC3/UVIS Imaging No No F547M WFC3/UVIS Imaging No No F673N WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No F438W POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12497 :visit-id "01" :proposal-version -1 :trans-version "20110509" :date "21-Jul-2011 13:36:06.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 5197488 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12497 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12497 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3054 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3391 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3168 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3391 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3164 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3391 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3167 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3391 :pcs-gap 0 ) true 4 0 The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12497 :visit-id "02" :proposal-version -1 :trans-version "20110509" :date "21-Jul-2011 13:36:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 5197488 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12497 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12497 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2940 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3051 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3053 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12497 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3053 :al-overhead-at-end 116 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3275 :pcs-gap 0 ) false 4 0