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

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. The Solar Neighbourhood Sample…. Database of ‘potentially nearby’ PNe

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

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  1. 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

  2. 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)

  3. New giant PNe in the solar neighbourhood PFP 1 (Pierce et al. 2004) FP 1824-0321 (Frew et al., in prep.) FP 0905-3033 (Frew et al., in prep.) 30’ RCW 24 (Frew et al. 2006) 30' 30'

  4. Planetary nebula or ionized ambient ISM… • Sh 2-174, DeHt 5, RE 1738+665, Sh 2-68, HDW 5… • PG 0108+101, PG 0109+111, KPD 0005+5106, 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’

  5. Ha SB – radius relationAll calibrators (n = 114) logS(Ha)= -3.42(±0.21)logR – 5.23(±0.16)

  6. High-excitation PNe (n = 16)Close-binary PNe (n = 11) HE PNe: squares CE PNe: triangles Others: crosses Increasing mass M  S(Ha)½

  7. ‘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 Hband very weak or absent [O II], [N II] and [S II] emission • CS is hot (Teff > 100 kK), and luminous relative to nebular flux • Large scale height, |z| = 340 pc • Low ionized masses ≤ 0.25 M

  8. 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

  9. Sh 2-71 does not have a close binary nucleus…The true CS has been misidentified in the literature The true CS (mB ≈ 19) is directly at centre (arrowed) Credit: Adam Block / KPNO

  10. Calibrating post-common envelope PNe # High excitation * Inferred close binary (Afsar & Bond 2005)

  11. Post-CE PNe: Morphologies NGC 2346 PHR 1818-1526 NGC 1360 NGC 6578 ? AAO/UKST Survey Credit: H. Bond / HST/ NASA Shapley 1 SuWt 2 Abell 65 NGC 5979 AAO/UKST Survey Credit: ESA/ESO/NASA DSS. Bipolar and toroidal rings, ‘Filled-centre’ ellipticals …but no double-shell ellipticals

  12. 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

  13. 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%

  14. 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 !!

  15. The Brown Dwarf Desert Figure from Grether & Lineweaver (2006)

  16. 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 deepBVRIJHK photometry of all CSPNin local volume-limited PN sample. Utilise UKIDSS, VHS data… SPITZER… • Single stars can do it !!

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