1RXS J214303.7+065419/RBS 1774: A new isolated neutron star candidate

Abstract

We report on the identification of a new possible Isolated Neutron Star candidate in archival ROSAT observations. The source 1RXS J214303.7+065419, listed in the ROSAT Bright Source Catalogue as RBS 1774, is very soft, exhibits a thermal spectrum well fitted by a blackbody at T ∼ 90 eV and has a low column density. NH ∼ 5 × 1020 cm-2. Catalogue searches revealed no known sources in other energy hands close to the X-ray position of RBS 1774. Follow-up optical observations with NTT showed no peculiar object within the X-ray error circle. The absence of any plausible optical counterpart down to mR ∼ 23 results in an X-ray to optical flux ratio in excess of 1000.