HII regions slides

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ISM:ISM: why?built from remains of stars(i) during life: stellar winds (slow and steady during lifetime)(ii) end of life: ejected massive envelopes (PN, novae)(iii) end of life: supernova explosionsThe ISM is a transitory phase of matter but plays a majorrole1) stars are re-born from it2) planets are formed from it3) we are born from it!
Page 1: Today:Recap on 1 st lecture:- Basic
Page 7 and 8: The Trapezium Clusterdominant star:
Page 9: Reflection nebulae
Page 13 and 14: A global model:the 3+1 phases of th
Page 17 and 18: Hot, ionized medium (HIM)Arises thr
Page 19 and 20: M101
Page 21 and 22: Today:HII regions:- Ionization/reco
Page 23: Rosette Nebula2 O-stars
Page 26 and 27: Photoionisation5432113.6 eV = < 912
Page 28 and 29: RecombinationAttraction between pro
Page 30 and 31: in summary
Page 32 and 33: Thermalization of energies and ioni
Page 34 and 35: Photoionisation rate [number of eve
Page 37: Ionisation balanceEquilibrium occur
Page 40: ionisation structure
Page 43 and 44: Thermal balance in ionized nebulaeP
Page 45 and 46: Metals• Real nebulae contain more
Page 47 and 48: energy levels (➙ transitions) in
Page 49 and 50: Forbidden linesForbidden line: aris
Page 51 and 52: 1S 05.4 eV1D 22.5 eVcritical densit
Page 53 and 54:
(N + )(O 2+ )
Page 55 and 56:
Consequence of forbidden-line cooli
Page 57:
energyTemperaturesObservation T e
Page 61 and 62:
AbundancesNow we know T e and n ewe
Page 63 and 64:
Problem:We need to know abundance o
Page 65 and 66:
Last lecture(s):Recap on essentials
Page 67 and 68:
Forbidden line =Collisionally excit
Page 69 and 70:
energyTemperaturesObservation T e
Page 71 and 72:
Now we know T e and n ewe can calcu
Page 73 and 74:
30 Dor (HST ACS)• Observe with sp
Page 75 and 76:
n e
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So how do we find out what’s in t
Page 79 and 80:
…but is it?• Unfortunate proble
Page 81 and 82:
Any other ideas?• Possibility 2:
Page 83 and 84:
PN: Abell 30NGC 1501Abell 30
Page 85 and 86:
HST imaging
Page 88:
Open questions• No direct observa
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