1. 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

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

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

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, P orb =16.8 hr  P s =12.6 ms  M p =1.24+/-0.11 M sun  M 2 =0.78+/-0.04 M sun, 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 We propose that NS+He star system may be the progenitor of IMBPs with a short-orbital-period like PSR J1802-2124 Our work

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

9. Initial distribution of NS + He star systems

10. An evolutionary example to PSR J1802-2124  Eggleton stellar code  NS + He star system  Eddington accretion limit  Orbital angular momentum loss Gravitational wave radiation magnetic braking isotropic winds

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

12. 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

13. Thank you!