INTEGRAL Observations of the Vela Region Focusing on Vela X-1
The Vela region has been observed for 1.7 Ms in November 2005 by the INTEGRAL satellite. We present preliminary spectral and temporal results of Vela X-1, an eclipsing neutron star hosted in a wind-accreting high-mass X-ray binary system. Using data from ISGRI, SPI and JEM-X, we firmly confirm the existence of cyclotron resonant scattering features (CRSF) at ~27 keV and ~54 keV, implying a neutron-star magnetic field of ~3 10^12 Gauss, and the presence of an iron emission line at ~6.5 keV. During two strong flares those parameters remained unchanged. Furthermore we measure the neutron-star spin period of 283.6 s, indicating a still constant trend.
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