X-ray Absorption Spectroscopy of the Multi-Phase Interstellar Medium: O & Ne Abundances Astro-ph: Yangsen Yao Q.Daniel Wang

1.Importance : Stars  SNe  Metal of ISM  Stars  SNe  …… a. The abundance in the ISM and stars provides constraints on the physical processes involved in SF & evolution. b. Heating  dust grain in the ISM  Cooling c. Observational data =?= Theory model interpretation

2. Question: a. Complex forms: atomic, molecular and solid dust grain; b. Complex states: cold(<100K), warm(~8000k), photo-ionized hot (1E6 K), collisionally ionized c. Depletion from condensation Enrichment from destruction

d. Optical & UV  cold/warm phases; (The model of the physical and ionization conditions) e. Stellar abundance measurement: (C,N,O of solar-like stars : downward 25%~45%, Asplund et al. 2005) f. Ne/O >2.5 or no such high Ne/O ratio(Drake& Testa 2005; Schmelz et al. 2005)

3. X-ray absorption spectroscopy: a. K- and L-transitions of carbon to iron b. Less affected by extinction  probe larger column densities c. Ne/O ratio & the absolute abundance of O/H (Takei et al. 2002; McCray & Snow 2004) d. XMMS-Newton & Chandra

4. Data: LMXB, 4U : P-orb = 685s l,b=(2.79d,-7.91) & D~7.6 Kpc Ne~2.7*10E20 cm-2 LMXB  serious stellar contamination LETG (Brinkman et al.2000,15ks), OII HETG (Cabizares et al. 2005, 9.7ks), NeIX ACIS (Cabizares et al. 2005, 10.9ks), NeIX

CIAO and CALDB Source spectra: rebin MEG+LETG(1st-6th grating) Continuum: BB + BKNPL +10 broad Gaussians N(H)~2.0*E21 cm-2

5. Result:

Abslin model: the line centroid; velocity dispersion; column density; temperature; Metal abundance;

Cold + Warm gas: N(OI+OII+OIII)=0.75(0.48,1.22)*E18 cm-2 N(Ne)=2.3(1.9,2.7)*E18 cm-2  (Ne/O)=0.3(0.2,0.5) or 2.1(1.3,3.5) solar Hot Phase:

Local Bubble (~1E6K)  3/4 keV Galactic bulge  enhance X-ray

21 cm: N(HI)=1.5*E21 cm-2 E(B-V)~0.32  N(HI)+N(H2)~1.9*E21 cm-2

6. Conclusions: a. The Column densities of OI, OII, OIII  Cold (neutral) O abundance of 0.3 solar. Warm O abundance of 2.0 solar. b. Ne abundance of 1.2 solar and Ne/O~2.1, consider compound ISM  ~1.5 lower c. Hot gas: Ne/O~1.4 solar, which is insensitive to the exact temperature distribution assumed. d. Atomic phases abundance from x-ray measure: Ne/O ratios < emission line from stars.

An Overview of Extremely Large Telescopes Projects Astro-ph/ R. G. Carlberg

1. The Giant Magellan Telescope:

2. The Thirty Meter Telescope: , US$700M

3. The Euro-50 Project: 1990-

4. The Overwhelmingly Large Telescope Project: 1,250M Euro