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He star evolutionary channel to intermediate-mass binary pulsars with a short-orbital-period

He star evolutionary channel to intermediate-mass binary pulsars with a short-orbital-period. Chen Wen-Cong. School of Physics, Peking University Department of Physics, Shangqiu Normal University. Normal Radio Pulsars and Millisecond pulsars. Normal radio pulsars. MSPs.

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He star evolutionary channel to intermediate-mass binary pulsars with a short-orbital-period

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  1. He star evolutionary channel to intermediate-mass binarypulsars with a short-orbital-period Chen Wen-Cong School of Physics, Peking University Department of Physics, Shangqiu Normal University

  2. Normal Radio Pulsars and Millisecond pulsars Normal radio pulsars MSPs

  3. Recycled Scenario of MSPs Spin Periods death line X-ray pulsars

  4. Binary pulsars • Low mass binary pulsars (LMBPs) millisecond pulsar + He WD • Intermediate mass binary pulsars (IMBPs) mildly recycled pulsar + CO/ONeMg WD spin periods, magnetic field, and orbital eccentricities of IMBPs are considerably greater than those of LMBPs

  5. PSR J1802-2124 • circular orbit, Porb=16.8 hr • Ps=12.6 ms • Mp=1.24+/-0.11 Msun • M2=0.78+/-0.04 Msun, CO white dwarf (Ferdman et al. 2010, ApJ) Light pulsar, heavy WD, short orbital period, moderate long spin period imply that it experiences a peculiar evolutionary history

  6. Previous works • L/IMXB, Roche lobe overflow, common envelope, spiral in, short timescale super-Eddington accretion (van den Heuvel 1994) • thermal-viscous instability of the accretion disks in IMXBs may result in the birth of a mildly recycled pulsar (Li 2002) • Tauris et al (2000)found that IMBPs with wide orbit (> 3 d) can be formed through a short-lived highly super-Eddington mass transfer phase Our work We propose that NS+He star system may be the progenitor of IMBPs with a short-orbital-period like PSR J1802-2124

  7. Population synthesis Results: CC: core collapse AIC: accretion induced collapse

  8. Initial distribution of NS + He star systems

  9. An evolutionary example to PSRJ1802-2124 • Eggleton stellar code • NS + He star system • Eddington accretion limit • Orbital angular momentum loss Gravitational wave radiation magnetic braking isotropic winds

  10. Evolutionary results (Chen, Li & Xu 2011, A&A, in press) Observed parameters of PSR J1802-2124:

  11. Summary • There exist sufficient IMBPs with a short-orbital-period (SOP) in the Galaxy • NS + He star channel may be responsible for the formation of most IMBPs with a SOP. • AIC process makes a main contribution in forming SOP IMBPs

  12. Thank you!

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