We report the results of an analysis of data obtained with the INTEGRAL , Swift and RXTE observatories during the 2010 April and September outbursts of the X-ray pulsar RX J0440.9+4431 .
The temporal and spectral properties of the pulsar in a wide energy band ( 0.6 - 120 keV ) were studied for the first time .
We discovered a \sim 32 keV cyclotron resonant scattering feature in the source spectrum , that allowed us to estimate the magnetic field strength of the neutron star as B \simeq 3.2 \times 10 ^ { 12 } G. The estimate of the magnetic field strength was confirmed by a comprehensive analysis of the noise power spectrum of the source .
Based on the recurrence time between Type I outbursts the orbital period of the binary system can be estimated as \sim 155 days .
We have shown that the pulse profile has a sinusoidal-like single-peaked shape and has practically no dependence on the source luminosity or energy band .