Survey of recent paper on ionized gaseous nebulae

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Survey of recent paper on ionized gaseous
nebulae

• By Wang Wei

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C and O galactic gradients Iobservational
values from ORLs

• 8 Galactic H II regions between 6.3 and 10.4 kpc
  from GC.
• Using UVES on VLT
• First time for C gradient to be derived for such
  a large sample
• Z from ORLs hardly affected by Te and Ne
• O O(OI ?7772, or t2 OII ??3727) O(V1)
• C C(?4267) ICF(C)
• ICF(C) is from Garnett et al.(1999) and t2 from
  comparison between Te, ionic Z from ORLs and
  CELs.

Esteban et al,astro-ph/0408379
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?log (O/H) -0.0440.010 ?log (C/H)
-0.1050.019 ?log (C/O)
-0.0610.020 In unit of dex kpc-1
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C and O galactic gradients II a solution to the
C enrichment problem

• different chemical evolution models give
  different C yields and thus different C/H value
  and C/O gradients
• Constraints from observations of H II regions,
  dwarf stars and solar values
• 11 set of models to fit them.
• Model 1 and 2 fit best ? indicate C yields
  increase with Z due to stellar winds in MS and
  decrease with Z due to stellar wind in LIMS.

Carigi et al,astro-ph/0408398
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Constraints for present ?Z
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Constraints for C/O history
are dwarf star from Ackerman 2004
are H II regions from Paper I Minimum C/O in
left panel can not be explained by any
models Need data outside 6-11 kpc
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Indications

• Fraction of C produced by MS increase with
  decreasing r ( thus with increasing O/H)
• For MS, the C yields increase with Z while for
  LIMS they decrease with Z

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Indications
MS dominate the c enrichment at early
times (12log(O/H) lt 8 ) Later on, the
contribution by MS and LIMS become comparable
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UV extinction properties in the M.W

• Using IUE spectra for 418 O3 to B5 stars for the
  determination of UV extinction.
• Combined with 2 MASS photometry ? Rv and also
  Fitzpartrick-Massa (FM) parameters
• The largest study with FM parameter determined
• It has a wide range of environments (from dense
  molecular clouds to diffuse ISM) and Av ( from
  0.50 to 4.80)
• It extends far beyond ( with 30 sightlines having
  distances gt 5 kpc )

Valencie et al,astro-ph/0408409
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• F M parameters
• k(x) E(?-V)/E(B-V) c1 c2x
  c3D(x,?,x0)c4F(x)

c1, c2 ? intercept and slope of the linear
background c3, c4 ? the strength of the bump and
the curvature of the FUV rise ?,x0 ? central
wavelength and width of the bump Solid
this work Dashed CCM law Dash-dot this work
from average FM parameters. Dotted
Fitzpatrick 1999 from FM parameters CCM law
Cardelli, Clayton, Mathis 1988
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Conclusions

• 1. the CCM law applies for 93 of the sightlines,
  implying dust processing in the Galaxy is
  efficient and systematic
• 2. the central wavelength of the 2175 bump is
  constant
• 3. The 2175 bump width is dependent on
  environment
• 4. Four sightline show systematic deviations
  from CCM HD 29647, 62542, 204827 and 21021. They
  all sample dense, molecular clouds

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A search for very young PNe

• The transition from AGB stars to PN is poorly
  understood (short time scale), but important to
  understand the shaping of PNe
• A sample of hot post-AGB stars, selected from
  their optical and infrared properties
• VLA observations at 8.4 GHz, 2.5 beamsize.
• 10 out of 16 sources are detected ? ionization
  has already started
• Compared with other work

Umana et al,astro-ph/0409333
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Summary of nebular characteristics of detected
As PNe are more younger, they should be more
dense and compact , thus TB and EM should be
larger (at orders of 103104 K and 106-108 cm-3
pc). But .. !
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Comparisons with AK91
TB
EM
AK91 (Aaquist Kwok 1991), their sample is
consistent with the hypothesis of vPNe TB and
EM from this work is much lower than from AK91,
while infrared excess is much larger
Contradiction ?
FIR(1e-14 W/cm-2)
Fradio(mJy)
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Similar dust characteristics
fraction
SAO 244567, the youngest known PNe
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Extremely young PNe younger than AK91 sample
From Volk Kwok 1985 Present sample may be at
the very start of ionization
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Physical structure of PNe the large and evolved
NGC 1360

• Ha images and high-dispersion echelle spectra
• Best fit gives
• a prolate ellipsoidal shell, with major axis
  twice as long as minor axis, tilted by 60 deg.
• kinematic age of shell 10000 yr, density lt 130
  H-atom cm-3
• No sharp inner edge thus no on-going compression
  by a fast stellar wind
• FLIERs near the end of its major axis expand
  faster and younger than the nebular shell

Goldman et al,astro-ph/0407568
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Morphology and kinematics
Ha echellogram
Ha image
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Ha profile
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FLIERs
Knot at 260 has velocity about 100 km s-1 They
argue these knots are FLIERs
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ISO observations of the GC ISM

• Goal the thermal balance and the origin of the
  high temperatures (200 K) of the molecular gas
• 19 molecular peaks located far from thermal
  radio-continuum or far-IR sources
• ISO SWS02, LWS01, LSW04, IRAM-30m
  (H35a,H39a,H41a)
• Extinction determined by several methods
• lower (25 mag) and upper (60 mag) limits
• ? main errors for line intensities and
  abundances

Fernandez et al,astro-ph/0409334
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Conclusions

• Fine structure lines N II and S III in 16
  sources, O III in 10 sources
• N and Ne and S abundances (8 sources )
• Ne abundance is similar to that of HII
  regions in the 5-kpc ring and in starburst
  galaxies while S is higher.
• Teff 32000- 3700 K and ionization parameters
  U ( -1 gt log U gt -3)
• All these are similar to those found in low
  excitation starburst galaxies ? consistent with
  a short burst of massive star formation 7 Myr
  ago ? source of high temperature
• Ne II to FIR continuum ratio similar to
  external galaxies
• dust heating corresponds to the ionizing
  source of gas
• ? FIR continuum in Active galaxies is
  associated to dust heated by stellar and not by
  the AGN

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Errors are caused by extinction
uncertaintiesgreen fit for GC thick black
fit for inner GCthin black fit for starburst,
AGNs and ULIRGs from Genzel et al 1998
ULIRGs
AGNs
Starburst gal.
Galaxy
L(FIR) L?
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The populations of PNe in the direction of the
Galactic Bulge

• 44 PNe observed, merged with published ones,
  totally 164 PNe
• Aim chemical composition and stellar emission
  features ( WR stars or Weak Emission Line Stars
  -- WELS )
• subsample b bulge sub-sample d related to disk
• Findings 18 new WR(15 in b and 3 in d) and 23
  WELS
• WC sequence is an evolutionary sequence
  early-type WC being surrounded by low density
  PNe

Gorny et al,astro-ph/0409532
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Statistics

• Difference
• Later than WC 10
• WC2 to WC4
• WC5, WC6
• Highly dependent
• on selection effects
• ( heavy extinction,
• small diameter).
• Easy to detect less
• luminous CS and
• thus late-type WR
• WR PNe proportion
• are larger in bulge than in disk

2 4 6
8 10 11
WC type
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Abundances

• Bulge .vs. disk
• Narrower and more skewed to high O/H
• Mean 25 75
• B8.45 8.21 8.68
• D8.32 7.93 8.59
• O/H gradient flattens in the most internal parts
  of The galaxy. Maybe change sign, in line with
  results from B-stars (Smartt et al 2001)

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Abundances
WR PNe .vs. other Remarkably similar
distribution O/H is WR stars are not
significantly affected by nucleosynthesis and
mixing in the progenitors
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Identification and characterization of faint
emission lines in the spectrum of IC 418

• To investigate the behavior of weak permitted
  emission line in the aim to understand abundance
  discrepancies
• IC 418 high surface brightness, apparent
  simplicity, low excitation
• Down to 10-5 intensity of Hb
• 9 km S-1 instrumental FWHM, line profile can be
  used to constrain excitation processes

Sharpee et al,astro-ph/0407186
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Results
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Line profiles
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Line profiles
N II 6527 inconsistent with others Possible
unknown blend Line profiles to isolate the
spatial origins, example OI 7772,9266 profile
similar to O II, indicating they are formed
from O rather O0 ? electron recapture courses OI
8446 profile similar to O I, thought to be
excited by fluorescence From O0 ground stats
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Ionization energy .vs. FWHM
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Other processes are important in exciting some
putative high level recombination lines for OII
and NII, while DR is too weak Root cause for
abundance discrepancies remains unclear