Late B-type stars and their candidate companions resolved with Chandra

We present the first results from a series of Chandra observations carried out with the aim to examine the origin of X-ray emission in main-sequence late B-type stars. We use high spatial resolution X-ray observations to enlighten the prevalent speculation that previously unknown late-type or low-mass companion stars are the sites of the X-ray emission, instead of the B-type primaries. Here we present the results for HD1685, HD113703, HD123445, HD133880, and HD169978. Adaptive optics observations have recently revealed at least one faint object near each of these B-type stars (at separation of 1-6"). Four of the new infrared objects show infrared colors and magnitudes typical for low-mass pre-main sequence stars, and are likely true companions to the 10-50 Myr old B-type stars. These multiple systems are now resolved for the first time in X-ray light