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Home , Asymptotic giant branch

arXiv:astro-ph/9910230v1 13 Oct 1999 rnh h ple rcdr iik h astase nb in ( mas transfer C/O-WDs whi massive mass RGB, more the the the the towards mimicks to leave Contrary evolved procedure to applied models started The the model branch. and the off switched When virtually mass. depending positions dwarf appropriate white at evolution RGB the nated M 1 a of h eW opno fteMPPRJ0250 Ncsr tal found et They (Nicastro 1998). J1012+5307 al. PSR et dete MSP Sarna (1998) the also al. of et companion Driebe He-WD models the evolutionary their on Based millisecond to Application 2. mass. their smaller the slower the reee l 19,19)ivsiae h vlto fHe- of evolution the investigated 1999) (1998, spectrosco 0 from range al. known independe is 1998 et calculated mass al. Driebe be He-WD et can the b Driebe systems provided cooling MSP (see properties the of studies If ages dw theoretical the (MSP). white from therein) two known millisecond is either a WDs Therefo and with (RGB). dwarf systems branch white the binary giant a where in red systems components the binary along common t in evolving known events are exchange mass (He-WDs) and/or cores loss mass with dwarfs white Low-mass Evolution Dwarf White 1. eds. Wielebinski, R. and Wex, N. Kramer, M. sn h pcrsoi aao a ekike l 19)an (1996) al. ratio mass et the Kerkwijk Thus, van of resp. data (1998), spectroscopic the using w decrease which hydr masses ongoing envelope The large by burning. M ages provided signifi nuclear spin-down is residual shows the this He-WDs as He-WDs to for due of mass-radius-relation effects order The same the cooling pulsars. of in e. resulting i. th , along Gyr, effective cycle low pp very the to via down burn asymptotic to continue the can through He-WDs evolved also have progenitors whose S ofrneSre,Vol. Series, Beyond Conference and ASP 2000 — Astronomy Pulsar WD seB¨ce ta.19) ncnrs oCOWs eWsco He-WDs C/O-WDs, to contrast In 1997). al. Bl¨ocker et (see srpyiaice ntttPtdm osa,Germany Potsdam, Potsdam, Institut Astrophysikalisches Sch¨onbernerD. Germany Bonn, f¨ur Radioastronomie, Max-Planck-Institut Bl¨ocker T. and Driebe T. pulsars dwarfs: millisecond white for helium Applications of evolution The . ⊙ 18 mdlwscluae pt h i fteRB ihms ost loss mass High RGB. the of tip the to up calculated was -model M < WD / M ⊙ < 3 × 0 . 10 5uigtecd fB¨ce 19) h evolution The Bl¨ocker (1995). of code the using 45 8 1999 , M M pulsar WD 1 M 0 = /M WD He . 19 − ∼ > WD ± 0 . 0 M 5 . ≈ 2M 02 ⊙ 9 . abnoye core), / , 5 ⊙ ± in rnhphase, branch giant n 0 and mndtems of mass the rmined gso h re of order the of ages ntedsrdfinal desired the on 0 D ntemass the in WDs atevolutionary cant tyo h pulsar the of ntly alnne al. et Callanan d . nr systems. inary edafcooling dwarf te vnKerkwijk (van 3 py. oln branch cooling e n references and , gnbrigin burning ogen e eWsare He-WDs re, hvoro He- of ehaviour oo salow a is donor fmillisecond of t increasing ith . eutfrom result o 15 rso with or arfs ,19,see 1995, ., ± oswas loss s 0 ldown ol . 2M 02 ermi- ⊙ 2 Driebe et al.

100

J1713+0747 J1012+5307 10 J0034-0534 Teff = 4000 K B1855+09 Teff = 10000 K 1 J0437-4715 Age/Gyr T = 15000 K eff

0.1 B0820+02 Teff = 20000 K

0.01 0 0.2 0.4 0.6 0.8 1

MWD/Msun

with He-core white dwarf with C/O-core

Figure 1. Ages of 6 MSP systems based on pulsar measurements as a function of the WD companion mass (see Burderi et al. 1998). The boxes refer to the uncertainties of spin-down ages and mass determina- tions. Cooling ages for evolutionary He- and C/O-WD models (Driebe et al. 1998, Bl¨ocker 1995) are given for four effective temperatures.

et al. 1998, priv. comm.) gives a pulsar mass Mpulsar = 1.43 ± 0.25 M⊙ and 1.81 ± 0.25 M⊙, resp. From our models we derived a white dwarf age of ≈ 6 Gyr in excellent agreement with the pulsar’s spin-down age of 7 Gyr. We studied other MSP systems as well assuming the correspondence of white dwarf cooling age and τspin−down. Selecting only systems with well given ages and/or masses, the white dwarf effective temperatures and surface can be determined with the present evolutionary models. Figure 1 shows the results for 6 MSP systems. Note that the consideration of fully evolutionary He-WD models is crucial for the determination of the effective . More details will be given in Sch¨onberner et al. (1999).

References

Bl¨ocker, T. 1995, A&A 297, 727 Bl¨ocker, T. et al. 1997, in: White Dwarfs, J. Isern, M. Hernanz, E. Garcia-Berro (eds.), Kluwer, Dordrecht, p. 57 Burderi, L., King, A. R., Wynn, G. A. 1998, MNRAS 300, 1127 Callanan, P. J., Garnavich, P. M., Koester, D. 1998, MNRAS 298, 207 Driebe, T., Sch¨onberner, D., Bl¨ocker, T., Herwig, F. 1998, A&A 339, 123 Driebe, T., Bl¨ocker, T., Sch¨onberner, D., Herwig, F. 1999, A&A 350, 89 van Kerkwijk, M. H., Bergeron, P., Kulkarni, S. R. 1996, ApJ 467, L89 Nicastro, L. et al. 1995, MNRAS 273, L68 Sarna, M. J., Antipova, J., Muslimov, A. 1998, ApJ 499, 407 Sch¨onberner, D., Driebe, T., Bl¨ocker, T., 1999, A&A, submitted