X-ray Absorption Spectroscopy of the Multi-Phase Interstellar Medium: O & Ne Abundances

Astro-ph:0512486Yangsen Yao Q.Daniel Wang

1.Importance : Stars SNe Metal of ISM Stars

SNe ……a. The abundance in the ISM and stars provi

des constraints on the physical processes involved in SF & evolution.

b. Heating dust grain in the ISM Cooling c. Observational data =?= Theory model inte

rpretation

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 co

nditions) e. Stellar abundance measurement:(C,N,O of solar-like stars : downward 25%~4

5%, 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 ironb. Less affected by extinction probe large

r column densitiesc. Ne/O ratio & the absolute abundance of

O/H (Takei et al. 2002; McCray & Snow 2004)

d. XMMS-Newton & Chandra

4. Data:LMXB, 4U 1820-303: P-orb = 685s l,b=(2.79d,-7.91) & D~7.6 Kpc Ne~2.7*10E20 cm-2LMXB serious stellar contamination

LETG (Brinkman et al.2000,15ks), OIIHETG (Cabizares et al. 2005, 9.7ks), NeIXACIS (Cabizares et al. 2005, 10.9ks), NeIX

CIAO 3.2.1 and CALDB 3.1.0Source 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-2N(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) solarHot Phase:

Local Bubble (~1E6K)3/4 keVGalactic bulgeenhance X-ray

21 cm: N(HI)=1.5*E21 cm-2E(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/ 0512499R. G. Carlberg

1. The Giant Magellan Telescope: 2010-2016

2. The Thirty Meter Telescope: 2009-2015, US$700M

3. The Euro-50 Project: 1990-

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