Do post-common 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'
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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
PN Distance (kpc) Method Mass (M?)
HFG 1 0.6 0.3 spectroscopic parallax 0.5
NGC 1514 0.37 0.10 spect. parallax 0.03
NGC 2346 0.9 0.2 spect. parallax, extinction 0.06
LoTr 5 0.5 0.2 spect. par., Wilson-Bappu, trig. 0.13
SBS 1150599A 18 5 gravity method 0.17
SuWt 2 1.6 0.4 spect. parallax 0.06
DS 1 0.73 0.07 reflection effect 0.26
BE UMa 2.0 0.4 reflection effect 0.2
Abell 46 1.7 0.6 eclipsing binary 0.14
Abell 63 2.4 0.4 eclipsing binary 0.08
NGC 1360 0.38 0.2 Gravity, trig. parallax 0.13
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 !!