J/ApJ/752/148 κ-distributed electrons and OIII em. line (Nicholls+, 2012)
Resolving the electron temperature discrepancies in H II regions and
planetary nebulae: κ-distributed electrons.
Nicholls D.C., Dopita M.A., Sutherland R.S.
<Astrophys. J., 752, 148 (2012)>
=2012ApJ...752..148N 2012ApJ...752..148N
ADC_Keywords: Atomic physics ; H II regions ; Interstellar medium ;
Planetary nebulae
Keywords: acceleration of particles; atomic data; atomic processes;
H II regions; ISM: abundances; planetary nebulae: general; plasmas
Abstract:
The measurement of electron temperatures and metallicities in H II
regions and planetary nebulae (PNe) has--for several
decades--presented a problem: results obtained using different
techniques disagree. What is worse, they disagree consistently. There
have been numerous attempts to explain these discrepancies, but none
has provided a satisfactory solution to the problem. In this paper, we
explore the possibility that electrons in H II regions and PNe depart
from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a
"κ-distribution" for the electron energies. Such distributions
are widely found in solar system plasmas, where they can be directly
measured. This simple assumption is able to explain the temperature
and metallicity discrepancies in H II regions and PNe arising from the
different measurement techniques. We find that the energy distribution
does not need to depart dramatically from an equilibrium distribution.
From an examination of data from H II regions and PNe, it appears that
κ≳10 is sufficient to encompass nearly all objects. We argue
that the kappa-distribution offers an important new insight into the
physics of gaseous nebulae, both in the Milky Way and elsewhere, and
one that promises significantly more accurate estimates of temperature
and metallicity in these regions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 201 Collisional excitation rate ratios
table2.dat 86 31 [OIII] Line flux ratios versus kinetic temperature
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See also:
J/ApJS/208/10 : κ-distribution effects in HII regions (Dopita+, 2013)
J/MNRAS/415/181 : Deep spectroscopy of NGC 7009 (Fang+, 2011)
J/ApJ/700/654 : Keck spectro. of extragalactic HII regions (Esteban+ 2009)
J/ApJ/656/168 : Spectrophotometry in NGC 5253 (Lopez-Sanchez+, 2007)
J/MNRAS/368/253 : Faint emission lines in M16, M20, N3603 (Garcia-Rojas+, 2006)
J/A+A/448/955 : Abundances of emission galaxies in SDSS-DR3 (Izotov+, 2006)
J/MNRAS/362/301 : Spectrophot. of the HII region S311 (Garcia-Rojas+, 2005)
J/ApJS/123/311 : Excitation rate coefficients for O III (Aggarwal+, 1999)
J/A+AS/103/273 : IRON Project II. C-like ions (Lennon+ 1994)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 F4.1 --- Tex/TU [0/20] Excitation threshold energy (expressed as
an equivalent temperature) over the kinetic
temperature TU (Equation (16))
6- 14 E9.4 --- Rate(2) Collisional excitation rate at κ=2
16- 24 E9.4 --- Rate(3) Collisional excitation rate at κ=3
26- 34 E9.4 --- Rate(4) Collisional excitation rate at κ=4
36- 44 E9.4 --- Rate(6) Collisional excitation rate at κ=6
46- 54 E9.4 --- Rate(10) Collisional excitation rate at κ=10
56- 64 E9.4 --- Rate(20) Collisional excitation rate at κ=20
66- 74 E9.4 --- Rate(50) Collisional excitation rate at κ=50
76- 84 E9.4 --- Rate(100) Collisional excitation rate at κ=100
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 K TU [5000/20000] Kinetic temperature TU
7- 13 F7.4 --- OIII(2) OIII line flux ratio at κ=2 (1)
15- 21 F7.4 --- OIII(3) OIII line flux ratio at κ=3 (1)
23- 29 F7.4 --- OIII(4) OIII line flux ratio at κ=4 (1)
31- 38 F8.4 --- OIII(6) OIII line flux ratio at κ=6 (1)
40- 47 F8.4 --- OIII(10) OIII line flux ratio at κ=10 (1)
49- 56 F8.4 --- OIII(20) OIII line flux ratio at κ=20 (1)
58- 66 F9.4 --- OIII(50) OIII line flux ratio at κ=50 (1)
68- 76 F9.4 --- OIII(100) OIII line flux ratio at κ=100 (1)
78- 86 F9.4 --- OIII(M) OIII line flux ratio (Maxwell) (1)
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Note (1): Flux ratio of [OIII] lines (F(5007)+F(4959))/F(4363).
Maxwell figures are computed using Lennon & Burke 1994 data
(J/A+AS/103/273/table3) (Maxwell distrubtion has κ=∞)
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 06-Feb-2014