Optical identification of IGR J 19140 + 0951

IGR J19140+0951 was discovered by INTEGRAL in 2003 in the 4-100 keV band. Observations with INTEGRAL and RXTE provide a tentative identification as a high-mass X-ray binary (HMXB) with a neutron star as accretor. However, an optical counterpart was thus far not established. Neither was the presence of a pulsar, which is commonly observed in HMXBs. We have observed IGR J19140+0951 with Chandra and find the source to be active at a similar flux as in previous measurements. The lightcurve shows a marginally significant oscillation at 6.5 ks which requires confirmation. We determine a sub-arcsecond position from the Chandra data and identify a heavily reddened optical counterpart in the 2MASS catalog. Optical follow-up observations with the William Herschel Telescope at La Palma exhibit a continuum spectrum coming out of extinction above 7000 Å without strong absorption or emission features. This and the red magnitudes suggest an early-type star rather than an accretion disk. All pieces of information confirm the suspicion that IGR J19140+0951 is a HMXB with additional circumstellar obscuration around the accretor.