Circinus X-1

Observation of Circinus X-1 in July 2007 revealed the presence of X-ray jets normally found in black hole systems; it is the first of the sort to be discovered that displays this similarity to black holes.

On June 14, 1969, an Aerobee 150 rocket, launched from Natal, Rio Grande do Norte, Brazil, obtained X-ray data during a scan of the Norma-Lupus-Circinus region that detected a well-isolated source at ℓ = 321.4±0.9° b = -0.5±2° (galactic), RA 15h 14m Dec −57° 49′ within the constellation Circinus and referred to as Circinus XR-1 (Cir XR-1).

[8] On June 23, 2015, an article published on NASA's Chandra X-Ray Observatory's website, revealed that an international team of astronomers has succeeded in determining its distance from Earth with more precision - via a method of triangulation of X-ray light emitted by the star, echoing through stellar clouds and interstellar dust - as being about 30,700 light-years.

[12] The X-ray and radio nebulae surrounding Circinus X-1 have properties consistent with a young supernova remnant.

[16] A (heavily reddened) precise optical counterpart (now known as BR Cir) was identified by Moneti.

X-ray light curves for Circinus X-1. The main plot shows the long term variability, and the inset plot shows the short term variability with a period of approximately 16.6 days. Adapted from Yu et al. (2024) [ 10 ]
X-ray light rings from a neutron star in Circinus X-1 (24 June 2015; Chandra X-ray Observatory ).