2003A&A...400..643B

4U 1812-12 is a faint persistent and weakly variable neutron star X-ray binary. It was observed by BeppoSAX between April 20th and 21st, 2000 in a hard spectral state with a bolometric luminosity of ∼2x10³⁶ergs/s. Its broad-band energy spectrum is characterized by the presence of a hard X-ray tail extending above ∼100keV. It can be represented as the sum of a dominant hard Comptonized component (electron temperature of ∼36keV and optical depth ∼3) and a weak soft component. The latter component which can be fitted with a blackbody of ∼0.6keV and equivalent radius of ∼2km is likely to originate from the neutron star surface. We also report on the first measurement of the power density spectrum of the source rapid X-ray variability, as recorded during a simultaneous snapshot observation performed by the Rossi X-ray Timing Explorer. As expected for a neutron star system in such a hard spectral state, its power density spectrum is characterized by the presence of a ∼0.7Hz low frequency quasi-periodic oscillation together with three broad noise components, one of which extends above ∼200Hz.