Do postcommon envelope objects form a distinct subset of PNe

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Do post-common envelope objects form a distinct
subset of PNe?

• David J. Frew
• Perth Observatory Macquarie University
• Q.A. Parker and the MASH Collaboration

Asymmetrical Planetary Nebulae IV La Palma, 21
June 2007
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The Solar Neighbourhood Sample

• Database of potentially nearby PNe
• Improved integrated fluxes in Ha and OIII
• Combination of literature and new spectroscopic
  data, kinematic data, and CSPN photometry
• Using revised/new distances, define a
  volume-limited sample within 1.0 kpc (presently,
  n 53)
• Extending sample volume to 1.5 kpc and 2.0 kpc
  (in progress)

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New giant PNe in the solar neighbourhood
PFP 1 (Pierce et al. 2004)
FP 0905-3033 (Frew et al., in prep.)
30
RCW 24 (Frew et al. 2006)

• FP 1824-0321
• (Frew et al., in prep.)

30'
30'
4
Planetary nebula or ionized ambient ISM

• Sh 2-174, DeHt 5, RE 1738665, Sh 2-68, HDW 5
• PG 0108101, PG 0109111, KPD 00055106, Hewett
  1
• PHL 932, EGB 5
• are not bona fide PNe, but simply ionized
  Strömgren spheres in ambient ISM
• Can conclude that no DO white dwarf is physically
  associated with a PN
• No sdB/sdOB (AGB-manqué) star has an associated
  ejecta nebula or PN

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Ha SB radius relationAll calibrators (n 114)
log S(Ha) -3.42(0.21)log R 5.23(0.16)
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High-excitation PNe (n 16)Close-binary PNe
(n 11)
HE PNe squares CE PNe triangles Others crosses
Increasing mass M ? S(Ha)½
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• Large high-excitation PNe (Kaler 1981)
• Round, elliptical, or amorphous (filled-centre)
  morphologies
• Large expansion velocities
• RT instabilities often seen
• Very high excitation HeII l4686 0.75 Hb and
  very weak or absent O II, N II and S II
  emission
• CS is hot (Teff gt 100 kK), and luminous relative
  to nebular flux
• Large scale height, z 340 pc
• Low ionized masses 0.25 M?

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The post-common envelope PN sample

• 23 close-binary PNe from De Marco (2006, IAU
  Symp. 234)
• Removed Abell 35, NGC 6302 and Sh 2-71
• LoTr 5 and NGC 1514 are included, but have
  unknown orbital periods
• Also added NGC 1360 (Bond Afsar 2005)
• Sample of 21 objects
• Selected 11 PNe with reliable distances and flux
  data, as calibrating objects

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Sh 2-71 does not have a close binary nucleusThe
true CS has been misidentified in the literature
Credit Adam Block / KPNO

• The true CS (mB 19) is directly at centre
  (arrowed)

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Calibrating post-common envelope PNe
High excitation Inferred close binary (Afsar
Bond 2005)
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Post-CE PNe Morphologies
NGC 2346
PHR 1818-1526
NGC 1360
NGC 6578
?
AAO/UKST Survey
Credit H. Bond / HST/ NASA
NGC 5979
Abell 65
SuWt 2
Shapley 1
AAO/UKST Survey
Credit ESA/ESO/NASA
DSS.
Filled-centre ellipticals
Bipolar and toroidal rings,
but no double-shell ellipticals
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Post-CE PNe Properties

• SB(Ha) 2.5 to 6.0 erg cm-2 s-1 sr-1 (0.2
  to 6.7)
• Average ionized mass (post-CE PNe) 0.17 0.13
  M?
• Average ionized mass (post-CE PNe, excluding HFG
  1) 0.13 0.08 M?
• Average ionized mass 0.64 0.5 M? (non
  post-CE local PNe, restricted range of SB)
• Post-CE PNe have low ionized masses. Extends
  conclusion of Bell et al. (1994) re Abell 63

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Binarity of CSPN optical/near-IR colours (2MASS
and/or DENIS)

• 53 PNe in solar neighbourhood (d 1.0 kpc)
• 7 wide binaries, e.g. Ciardullo et al. 1999
  (6/6 with 2MASS data show excess at J, H and/or
  K)
• 7 close binaries (4 have periods 5/6 in 2MASS
  show excess at J, H and/or K)
• 3 more CSPN have excess at J, H and/or K
• 16 show no IR excess
• 21 PNe have no observational data
• Of the 32 PNe with optical/near IR colours,
• total binary fraction 53 (agrees with
  Duquennoy Mayor)
• total close-binary fraction 13 - 31

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Selection bias?

• 2MASS photometry limit at J 16, Ks 15
• Detection limit for CS companion is M0V M8V,
  depending on luminosity of CSPN
• Alternatively, CS may have brown dwarf or cool WD
  companion, or be a merger product ...
• but recall the Brown Dwarf Desert (e.g. Marcy
  Butler 2000, Armitage Bonnell 2002, Grether
  Lineweaver 2006).
• Solar-type stars (i.e. PN progenitors) have an
  almost total absence of brown dwarf companions
  within 5 AU !!

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The Brown Dwarf Desert

• Figure from Grether Lineweaver (2006)

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Conclusions future work

• Close binary (post-CE) PNe have a distinct trend
  in SB-r space, shared by optically-thin, low
  mass, high-excitation PNe.
• Post-CE PNe have low ionized masses and
  distinctive filled-centre, bipolar or toroidal
  morphologies.
• Post-CE PNe comprise a minority of PNe. Should
  they be called true PNe?
• Need to continue search for close-binary nuclei
  via time-series photometry and RV monitoring
• Need deep BVRIJHK photometry of all CSPN in local
  volume-limited PN sample. Utilise UKIDSS, VHS
  data SPITZER
• Single stars can do it !!