Unveil accretion onset mechanisms of a normal outburst of EXO 2030+375

We propose to observe the Be/X-ray binary system EXO 2030+375 during its periastron passage for 30 ks to study the onset of the accretion activity. Accretion disc instability at the border of the magnetosphere have been evidenced by quasi-periodic hour-long flux oscillations detected during INTEGRAL serendipitous observations in 2011 and by EXOSAT in 1985. Existing RXTE snapshots observations during past outbursts are unable to characterise the way in which matter begins to penetrate into the magnetosphere. The unprecedented sensitivity of XMM-Newton and its continuous coverage will allow us to investigate in detail the opening of the magnetic gate for this high-magnetic field neutron star.