The Planetary Nebulae Luminosity Function for Galactic Bulge Planetary Nebulae

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The Planetary Nebulae Luminosity Function for
Galactic Bulge Planetary Nebulae

• Anna Kovacevic
• Quentin Parker, George Jacoby, Rob Sharp, Brent
  Miszalski

Legacies of the Macquarie/AAO/Strasbourg Ha
Planetary Nebula project Sydney, February 16-18th
2009
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Main points

• Background of Luminosity Function
• Problems and solutions
• Observations
• Reductions and preliminary results
• Excitation class
• Further exploitation of this data

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Background of the PNLF

• Theoretical foundation first laid out by Jacoby
  (89)
• Ciardullo et al. (89) fit the theoretical curve
  to 76 PNe in the dust-free regions in M31
• Proposed
• N(m) 8 e0.307M( 1 e3(M- M))
• to model the observations
• Found since to work across all galaxies Ciardullo
  (03)

Ciardullo et al. (1989)
?powerful extra-galactic distance indicator
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Problems and solutions

• Absolute magnitude of bright end invariant to
  population age
• ? requires CSs to be gt0.6Msolar, which
  corresponds to a mass on the main-sequence of
  gt2Msolar. Stellar evolution dictates only live
  for 1Gyr
• How can we account for PNLF bright end in
  elliptical (gt10Gyr) galaxies?
• Possible explanations.
• Ciardullo (05) ? massive central stars in old
  populations produced through binary evolution.
• - BSs where 2 1M? stars merged on MS to form
  a 2Msolar star

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What do the theorists think?

• Marigo et. al (2004,2006) assume single-star
  post-AGB evolution and used nebular models
• - constructed PNLFs for populations with
  different metallicities and star formation
  histories
• - Found bright end made up of PNe with CS
  masses 0.7-0.75Msolar
• ? Bright end absolute magnitude must be
  dependent on properties of underlying population
  
• Schonberner (2007) use radiation-hydrodynamical
  models simulations produce OIII luminosity
  evolution of PNe
• - Models suggest most PNe are optically thin
  with CS TEgt45000K,
• ? cannot explain bright end
• - Models with CS mass gt0.6Msolar dense,
  optically thick nebula do provide OIII
  luminosity required to populate bright end.

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What can we do to improve our understanding
observationally

• We have clear evidence that massive central stars
  in old elliptical galaxies do exist, so the
  question we need to answer now is how do they
  exist
• To understand how the PNLF works we need a
  complete, volume-limited sample that is near
  enough that we are able to resolve their
  morphologies as well as able to attain high S/N
  spectra relatively easily.
• This has been done for the Local 1kpc volume
  (Frew), the LMC(Reid) and the Galactic Bulge
  (this work).
• ? Questions we can ask
• Which parts of the LF do different population
  subsets (Type I, binary) occupy?
• Is the robustness of the PNLF just due to one
  of these subsets?
• Do PNe with a certain morphology/excitation
  class dominate certain parts of the PNLF?

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Round 1 - Chile
b
l

• 6 nights using MOSAIC-II camera on 4-m Blanco at
  CTIO
• Large mirror to minimise exposure times on the
  faintest PNe
• 36 x 36 camera
• 0.27/pixel
• Chose 10x10 region in the Bulge
• Excellent instrument
• Excellent site
• gt Fields placement ensuring all PNe observed
  with a minimum amount of fields.
• gt Ensuring maximum overlap to check
  flux-calibration between fields.
• gt Targeted Southern Bulge as higher number of
  PNe per field

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Chile cont

• Outcomes
• 6 nights of photometric sub-arcsecond seeing
  weather ?
• Observed 78 out of the 175 fields
• Observed 57 of PNe in 45 of fields
• Therefore 43 of PNe to observe in remaining 55
  of fields.
• With another 5 clear nights, we could achieve
  95 completeness for OIII observed PNe in the
  b lt 5 l lt 5 region

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Round 2 - Chile

• 5 nights using MOSAIC-II on 4-m Blanco at CTIO in
  late June 2009
• Mop up remaining fields

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Reductions

• Using CASU pipeline/toolkit developed by for the
  INT WFI data with CTIO add-ons
• First mosaics have been made

and starting to make measurements
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Examples
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Current PNLF for the Bulge

• Compiled for 101 PNe 44 listed in Escudero de
  Costa (2001) and 57 listed in Escudero et al.
  (2004).
• The 44 were taken from Kohoutek (1994) and
  Beaulieu et al. (1999)

Bl3-13
M2-26
Al2-0
M4-7
M3-19
H1-46
KFL2
M2-20
Bulge PNLF constructed by Maciel, priv. comm.
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Excitation class
low excitation object ? high NII/Ha little or
no HeII emission high excitation object ?
little or no NII HeII present

• Gurzadyan (1988) related the excitation class of
  the nebula to the temperature of the central star
  as well as the radius Gurzadyan (1991).

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Excitation class cont...

• Ratag et al. (1997) used spectra for 110 PNe
  within 20 degrees of the Galactic centre
• Excitation class defined by OII?3727/OIII?495
  9 for classes 5 and HeII ? 4686/HeI?5876 for
  classes gt5.

• Distribution of 138 PNe in the Galactic Plane.
• Excitation class defined by (OIII?5007OIII?4
  959)/Hß for low excitation objects and
  log((OIII?5007OIII?4959)/HeII) for high
  excitation PNe.

Number of PNe in each excitation class as
published in Gurzadyan and Egikyan (1991)
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Excitation class cont

• MASH does not compose of many medium excitation
  PNe.
• Same as found in LMC by Reid Parker (2006)

• Plot of OIII flux against excitation class of
  Escudero et al. (2004) sample

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Other avenues for this data