Query : 2009A&A...500..883S

2009A&A...500..883S - Astronomy and Astrophysics, volume 500, 883-889 (2009/6-3)

Updating the orbital ephemeris of Hercules X-1: rate of decay and eccentricity of the orbit.


Abstract (from CDS):

We present an update of the orbital ephemeris of the binary X-ray pulsar Her X-1 and determine an improved value for the rate of orbital decay. In addition, we report the first measurement of the orbital eccentricity. We analyzed pulse timing data of Her X-1 from X-ray observations by RXTE (Rossi X-Ray Timing Explorer) and INTEGRAL over the period 1996-2007. Accurate pulse arrival times were determined from solar system bary-centered photon arrival times by generating pulse profiles averaged over appropriately short integration times. Applying pulse phase connection techniques, it was possible to determine sufficiently accurate local ephemeris data for seven observation periods distributed over 12 years. Combining the new local Tπ/2 values with historical values from the literature we update the orbital ephemeris of Her X-1 to Tπ/2=MJD 46359.871940(6) and Porb=1.700167590(2)d and measure a continuous change of the orbital period of dPorb/dt=-(4.85 ±0.13)x10–11s/s. For the first time, a value for the eccentricity of the orbit of Her X-1 has been measured: ε=(4.2±0.8)x10–4.

Abstract Copyright:

Journal keyword(s): stars: binaries: general - stars: neutron - X-rays: general - X-rays: binaries - X-rays: individual: Her X-1 - ephemerides

Simbad objects: 2

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Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 V* V779 Cen HXB 11 21 15.0920532528 -60 37 25.630264596   14.4 12.27     O9III/Veq 1048 0
2 V* HZ Her LXB 16 57 49.8110126616 +35 20 32.486555472 11.90 14.89 13.63 13.88   B3/6ep 2019 0

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