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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 binarypulsars 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
Recycled Scenario of MSPs Spin Periods death line X-ray pulsars
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
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
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
Population synthesis Results: CC: core collapse AIC: accretion induced collapse
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
Evolutionary results (Chen, Li & Xu 2011, A&A, in press) Observed parameters of PSR J1802-2124:
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