In the irregular galaxy NGC 4449 lies a young core-collapse supernova remnant (SNR) with remarkable optical, radio, and X-ray luminosities. With an estimated age of just 50 - 100 years, it fills an important gap in our understanding of the evolutionary development of a SNR as its forward shock and stellar debris expand into the local circumstellar environment. This is a proposal to use STIS to obtain new UV spectra of this extraordinary object, an extreme example of objects that are now making the transition from free expansion to a shock-dominated phase. Optical spectra and X-ray observations show that emission from the SNR has changed since it was observed with the FOS in 1993. We will use STIS spectra together with existing ground-based observations to (1) explore the abundances and kinematic distribution of elements in the ejecta from this core-collapse SN and compare these with nucleosynthesis models; (2) probe the interaction of the SN blast wave with what must be a very dense environment to produce its extraordinary luminosity; and (3) assess the surrounding stellar population that gave rise to this SNR. UV observations with HST are critical to a better understanding of the SNR, since this is the only way to gain access to carbon and hence measure CNO abundance ratios needed to estimate the precursor mass, and the only way to characterize shocked gas with temperatures of order 100,000 - 300,000 K. The combination of UV sensitivity and narrow slit to better isolate the SNR and stellar components makes STIS ideally suited to the needs of this program.

This project is intended to obtain spectra of a single SNR in the irregular galaxy NGC4449. We are using the FUV (G140L) and NUV (G230L) gratings with the FUV and NUV MAMA detectors, as well as the G430L grating with the CCD. Our intent is to obtain a high quality spectrum of this object from the FUV through the visible. We want also to be able to compare the spectra of the SNR to nearby HII regions and a nearby compact star cluster. We have place orientation requirements on the visits to avoid having other objects in the slit very close to the SNR and to capture the nearby star cluster (as we described in our Phase I proposal). Since the region is crowded, we want all of the observations to have the same slit orientation, and so have imposed SameOrient speciall requirements. We will use the 0.2 arcsec by 52 arcsec slit for all of the the observations. Because the source is relatively faint we will are using the 52X0.2E1 apeture for the CCD observation to limit the CTE effects in the CCD. There are no realtime requirements. There are no special calibration requirements. ISM AND CIRCUMSTELLAR MATTER 12 false 0.0 0.0 false false false false SUPPORTED ISM EMISSION LINE NEBULA SNR J2000 J2000 STIS/FUV-MAMA Spectroscopic No No G140L 1425 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 POS-TARG DITHER 0.4 LINE false false 2 90.0 STIS-ALONG-SLIT 1 false Same orient constraint links visits (01 02 03) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. This visit consists of the acquisition and 3 orbits of FUV observations forllowed by one orbit of NUV observations of the SNR in NGC4449 (Tic-Visit :proposal-id 12462 :visit-id "01" :proposal-version -1 :trans-version "20110509" :date "30-Jul-2011 14:17:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 644160 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12462 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12462 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2991 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3075 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3075 :al-overhead-at-end 0 :internal-dur-at-end 115 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2965 :al-overhead-at-end 85 :internal-dur-at-end 396 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 4 0 Same orient constraint links visits (01 02 03) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. This visit consists of the acquisition and 3 orbits of FUV observations forllowed by one orbit of NUV observations of the SNR in NGC4449. It should be identical in terms of planning to Visit 1 (Tic-Visit :proposal-id 12462 :visit-id "02" :proposal-version -1 :trans-version "20110509" :date "30-Jul-2011 14:17:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 644160 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12462 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12462 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2991 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3075 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3075 :al-overhead-at-end 0 :internal-dur-at-end 115 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12462 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2965 :al-overhead-at-end 85 :internal-dur-at-end 396 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 4 0 Same orient constraint links visits (01 02 03) The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. This visit obtains the visible spectrum of the SNR in NGC4449 with the STIS CCD (Tic-Visit :proposal-id 12462 :visit-id "03" :proposal-version -1 :trans-version "20110509" :date "30-Jul-2011 14:18:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 55632 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12462 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12462 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3002 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 1 0