BACKGROUND DIAGNOSTIC POWER OF THE UV SAMPLING OF HST ISM RESULTS HIGH PRIORITY PROJECTS

1. ULTRAVIOLET SPECTROSCOPIC STUDIES OF DIFFUSE GAS IN AND NEAR THE MILKY WAYBLAIR D. SAVAGEUNIVERSITY OF WISCONSIN-MADISON BACKGROUND DIAGNOSTIC POWER OF THE UV SAMPLING OF HST ISM RESULTS HIGH PRIORITY PROJECTS

2. SPIRAL GALAXIES HAVE A COMPLEX MULTI-PHASE GASEOUS MEDIUM(Howk & Savage 1999)

3. NGC 891 WIYN V BAND IMAGE & UNSHARP MASK IMAGE0.7 “ seeing ( Howk & Savage 1999)

4. FUNDAMENTAL QUESTIONS • WHAT IS THE COMPOSITION OF THE GAS? • WHAT IS THE DISTRIBUTION OF THE GAS? • WHAT ARE THE PHYSICAL CONDITIONS OF THE GAS? • WHAT PHYSICAL PROCESSES CONTROL THESE CONDITIONS? • HOW DOES THE INTERSTELLAR GAS PARTICIPATE IN GALACTIC PROCESSES?

5. THE DIAGNOSTIC POWER OF UV SPECTROSCOPY ISM ATOMIC SPECIES DETECTED BY HST H I, D I B II C I, CI*, CI**, C II, CII*, C IV N I, N V O I, O I* Mg I, Mg II Al II, Al III Si I, Si II, Si II*, Si III, Si IV P I, P II, PIII S I, S II, S III Cl I Cr II, Mn II, Fe II, Co II, Ni II, Cu II, Zn II,Ga II, Ge II, As II, Se II, Kr I, Sn II, Tl II, Pb II ABUNDANCES DENSITY DIAGNOSTICS TEMPERATURE DIAGNOSTICS TRACES THE CNM, WNM, WIM, & HIM

6. ISM GAS PHASE ABUNDANCES z OPH (Savage & Sembach 1996)

7. GAS PHASE ABUNDANCES IN DIFFERENT ISM REGIONS Spitzer & Fitzpatrick (1993) Savage & Sembach (1996)

8. COOLING BY C II IN THE MILKY WAY vs DAMPED LYMAN ALPHA SYSTEMSLehner et al. (2004)

9. ASTROPHYSICAL JOURNAL (1956, VOLUME 124, 20)ON A POSSIBLE INTERSTELLAR GALACTIC CORONALYMAN SPITZER, JR. Princeton University Observatory Received March 24, 1956 “The ion O VI which is isoelectronic to Mg X, has a corresponding doublet at 1038 and 1032 Å and might be sufficiently abundant to produce measurable absorption, especially since the ionization potential of O VII has the relatively high value of 739 volts. Similarly the ultimate lines of N V and C IV, at about 1240 and 1550A, respectively, might be observable.”

10. High Ionization ISM / IGM Species CIE: Sutherland & Dopita (1993) Abundances: Anders & Grevesse (1989)

11. EXTENSION OF THE HIGHLY IONIZED IONS INTO THE HALOLYMAN SPITZER’S CORONA EXPONENTIAL SCALE HEIGHTS (HST +FUSE) Si IV 5.1±0.7 kpc C IV 4.4±0.6 kpc N V 3.3±0.5 kpc O VI 2 to 4 kpc

12. HIGHLY IONIZED GAS (O VI) IN AND NEAR THE MILKY WAY H2 model Sembach et al. (2000, ApJ, 538, L31)

13. The High Velocity H I + O VI Sky H I 21cm Emission O VI Absorption Sembach, Wakker, Savage, et al. (2003)

14. High Velocity Cloud Complex C Metallicity: Z ~ 0.1 – 0.2 (Wakker et al. 1999; Gibson et al. 2002) Distance: d > 5 kpc from the Galactic plane Mass: MHI > 1.2 x 106 Mo Complex C has little dust or H2 and its low N abundance implies that it is chemically young (Richter et al. 2001). Complex C is moving at high negative velocities (–170 to –100 km s-1). O VI absorption is detected at essentially the same velocities as the H I.

15. Highly Ionized Gas in Complex C Nine Complex C sight lines observed All show O VI absorption at Complex C velocities N(O VI) 4.7x1013 to 1.7x1014 cm-2 (hot H+ ~ 20% HTOTAL) v(H I) - v(O VI) = 0± 13 km s-1 Conductive interface model favored (Fox et al. 2003)

16. COMPLEX C WARM - HOT GAS INTERFACESFox et al. (2004)

17. 3C273 Mrk 421 NGC 4593 Chandra X-ray O VII absorption (Fang et al. 2003, ApJ, 586, L49) PKS 2155-304 ROSAT All-Sky Survey (Snowden et al. 1997, ApJ, 485, 125)

18. A SAMPLING OF HIGH PRIORITY ISM PROJECTS 1.WHAT ARE THE PROPERTIES OF CONDUCTIVE INTERFACES? Best explored along simple LISM lines of sight toward bright white dwarfs. ~60 orbits of STIS E140M observations 2.WHAT ARE THE PROPERTIES OF THE VERY HIGHLY EXTENDED GASEOUS ENVIRONMENT OF THE MILKY WAY? ~250 orbits of STIS E140M observations of 10 AGNs sampling HVCs interacting with gas in the outer environment of the Milky Way. 3.WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE ISM IN AN IRREGULAR GALAXY? ~300 orbits of STIS E140M, E230M, E140H, & E230H observations of LMC stars.

19. WHAT ARE THE FUNDAMENTAL PROPERTIES OF THE ISM IN AN IRREGULAR GALAXY? Ha Imagery (Danforth et al. 2002) O VI (Howk et al. 2002)