1. Mass Loss and Evolution of Low-Mass X-ray Binaries Xiang-Dong Li Department of Astronomy Nanjing University 2009-5-20

2. Low-Mass X-ray Binaries (LMXBs)

3. LMXBs and BMSPs Spin Periods Radio PSRs MS PSRs Spin-up line Magnetic fields LMXBs

4. From Deloye (2008)

5. Stability of Mass Transfer Two mass-radius exponents Stability requires that after mass loss the star is still contained by its Roche lobe. From Soberman et al. (1997)

6. Stable Mass Transfer Driving mechanisms –Loss of orbital angular momentum Gravitational radiation Magnetic braking –Nuclear evolution of the companion star From Deloye (2008)

7. Bifurcation Period in L/IMXB Evolution 1.5 M ⊙ + 1.0 M ⊙ From Pylyser & Savonije (1988)

8. P orb -M wd Relation in Wide Binary Pulsars From Rappaport et al. (1995)

9. Thermal Timescale Mass Transfer Mass transfer is dynamically stable but occurs on a thermal timescale if This requires that the donor star has a radiative envelope, or the convective envelope is not too deep. From Deloye (2008)

10. Evolution of IMXBs From Podsiadlowski et al. (2001) From Li (2002)

11. Dynamically Unstable Mass Transfer Massive donors with a convective envelope  Common envelope evolution  Ultracompact LMXBs From Deloye (2008)

12. UC-LMXBs TTMT CV-like RGB/AGB

13. Angular Momentum Loss by Magnetic Braking From Andronov et al. (2001) Standard MB Saturated MB

14. Radio Pulsar Mass Measurements PSR J1911-5958: 1.4 (+0.16,-0.10) 2S0921-630: 1.44 (±0.10) PSR J1909-3744: 1.438 (±0.024) PSR J0437-4715: 1.58 (±0.18) PSR J1012+5307: 1.6 (±0.20) M = 1.35±0.04 M ⊙ Thorsett & Chakrabarty 1999 Mass transfer is highly non-conservative during I/LMXB evolution

15. Mass and Angular Momentum Loss Circumbinary disk OutflowWind

16. Bifurcation Periods Model 1: conservative mass transfer + traditional MB law Model 2: conservative mass transfer + saturated MB law Model 3: non-conservative mass transfer + mass loss from L1 point + saturated MB law Model 4: non-conservative mass transfer + mass loss from the NS + saturated MB law

17. From Ma & Li (2009a)

19. Magnetic Capture Model for the Formation of UCXBs From van der Sluys et al. (2005)

20. A CB Disk in Work From Ma & Li (2009b)

22. Conclusions The standard model for L/IMXBs still fails to reproduce some of the main features of the observed LMXBs and MS PSRs. An unknown mechanism that mimics the features of a CB disk may be an important ingredient for understanding the overall evolution of I/LMXBs and CVs.