### Abstract

Lingua originale | English |
---|---|

pagine (da-a) | 44-50 |

Numero di pagine | 7 |

Rivista | ASTRONOMY & ASTROPHYSICS |

Volume | 2010-06 |

Stato di pubblicazione | Published - 2010 |

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### All Science Journal Classification (ASJC) codes

- Astronomy and Astrophysics
- Space and Planetary Science

### Cita questo

*ASTRONOMY & ASTROPHYSICS*,

*2010-06*, 44-50.

**New ephemeris of the ADC source 2A 1822-371: a stable orbital-period derivative over 30 years.** / Iaria, Rosario; Di Salvo, Tiziana; D'Ai', Antonino; Riggio; Burderi; Menna; Papitto.

Risultato della ricerca: Article

*ASTRONOMY & ASTROPHYSICS*, vol. 2010-06, pagg. 44-50.

}

TY - JOUR

T1 - New ephemeris of the ADC source 2A 1822-371: a stable orbital-period derivative over 30 years

AU - Iaria, Rosario

AU - Di Salvo, Tiziana

AU - D'Ai', Antonino

AU - Riggio, null

AU - Burderi, null

AU - Menna, null

AU - Papitto, null

PY - 2010

Y1 - 2010

N2 - We report on a timing of the eclipse arrival times of the low mass X-ray binary and X-ray pulsar 2A 1822-371 performed using all available observations of the Proportional Counter Array on board the Rossi X-ray Timing Explorer, XMM-Newton pn, and Chandra. These observations span the years from 1996 to 2008. Combining these eclipse arrival time measurements with those already available covering the period from 1977 to 1996, we obtain an orbital solution valid for more than thirty years. The time delays calculated with respect to a constant orbital period model show a clear parabolic trend, implying that the orbital period in this source constantly increases with time at a rate dot P_orb = 1.50(7) × 10-10 s/s. This is 3 orders of magnitude larger than what is expected from conservative mass transfer driven by magnetic braking and gravitational radiation. From the conservation of the angular momentum of the system we find that to explain the high and positive value of the orbital period derivative the mass transfer rate must not be less than 3 times the Eddington limit for a neutron star, suggesting that the mass transfer has to be partially non-conservative. With the hypothesis that the neutron star accretes at the Eddington limit we find a consistent solution in which at least 70% of the transferred mass has to be expelled from the system.

AB - We report on a timing of the eclipse arrival times of the low mass X-ray binary and X-ray pulsar 2A 1822-371 performed using all available observations of the Proportional Counter Array on board the Rossi X-ray Timing Explorer, XMM-Newton pn, and Chandra. These observations span the years from 1996 to 2008. Combining these eclipse arrival time measurements with those already available covering the period from 1977 to 1996, we obtain an orbital solution valid for more than thirty years. The time delays calculated with respect to a constant orbital period model show a clear parabolic trend, implying that the orbital period in this source constantly increases with time at a rate dot P_orb = 1.50(7) × 10-10 s/s. This is 3 orders of magnitude larger than what is expected from conservative mass transfer driven by magnetic braking and gravitational radiation. From the conservation of the angular momentum of the system we find that to explain the high and positive value of the orbital period derivative the mass transfer rate must not be less than 3 times the Eddington limit for a neutron star, suggesting that the mass transfer has to be partially non-conservative. With the hypothesis that the neutron star accretes at the Eddington limit we find a consistent solution in which at least 70% of the transferred mass has to be expelled from the system.

KW - Astrofisica

UR - http://hdl.handle.net/10447/50773

UR - http://adsabs.harvard.edu/abs/2010A%26A...515A..44B

M3 - Article

VL - 2010-06

SP - 44

EP - 50

JO - ASTRONOMY & ASTROPHYSICS

JF - ASTRONOMY & ASTROPHYSICS

SN - 0004-6361

ER -