NGC 5189 and the CRUX X-ray Source

Abstract

OF the objects in the southern hemisphere which are generally classified as planetary nebulae¹ undoubtedly the two with the most strikingly anomalous forms are NGC 6302 (refs. 2, 3) and NGC 5189 (refs. 4, 5). Attention has been drawn by Minkowski and Johnson to the fact that NGC 6302 lies close to the position of the cosmic X-ray source SCO XR-2. It is interesting therefore that NGC 5189 (13.5h–65°.7) lies in the direction of the X-ray source CRUX recently discovered by Harries et al.⁶ The uncertainty in the position of this source is considerable (especially in declination), two measures giving 13.7h–62° and 13.5h–66°. Thus clearly no positive identification can yet be claimed. Nevertheless, in view of the small number of known X-ray sources it seems quite remarkable to find even approximate agreement in positions between two of them and two such highly peculiar objects as NGC 5189 and NGC 6302 unless there is indeed some physical connexion.