The dipping X-ray source 4U 1822−37 was observed by Suzaku on 2006 Octrober
20 for a net exposure of 37 ks. The source was detected with the XIS at a 1-10
keV flux of 5.5×10−10 erg cm−2 s−1, and with the HXD
(HXD-PIN) at a 10-50 keV flux of 8.9×10−10 erg cm−2 s−1.
With HXD-PIN, the pulsation was detected at a barycentric period of 0.592437 s,
and its change rate was reconfirmed as −2.43×10−12 s s−1. The
1-50 keV spectra of 4U 1822-37 were found to be very similar to those of Her
X-1 in the slopes, cutoff and iron lines. Three iron lines (Fe Kα, Fe
XXV, and Fe XXVI) were detected, on top of a 1-50 keV continuum that is
described by an NPEX model plus a soft blackbody. In addition, a cyclotron
resonance scattering feature was detected significantly (>99% confidence),
at an energy of 33±2 keV with a depth of 0.4−0.3+0.6. Therefore,
the neutron star in this source is concluded to have a strong magnetic field of
2.8×1012 G. Further assuming that the source has a relatively high
intrinsic luminosity of several times 1037 erg s−1, its spectral and
timing properties are consistently explained