Labelled Hubble image of NGC 1073, showing quasars and IXO 5

The NASA/ESA Hubble Space Telescope has taken a picture of the barred spiral galaxy NGC 1073, which is found in the constellation of Cetus (The Sea Monster). The three star-like objects labelled here, PKS 0241+011, QSO B0240+011 and [VV96] J024333.6+012222, are actually not part of the galaxy. They are not even stars.

They are quasars, incredibly bright sources of light caused by matter heating up and falling into supermassive black holes in galaxies literally billions of light-years from us. From our distant perspective, they look like faint stars, but they are in fact some of the brightest objects in the Universe.

Another object in this field which has been studied by astronomers is a source of X-rays catalogued as IXO 5. X-ray sources are a tell-tale sign of high-energy phenomena. In this case, it is likely to be a binary system featuring a star and a black hole. As X-ray telescopes have less resolution than Hubble does, pinpointing the specific star in Hubble’s image that corresponds to the X-ray emissions is tough. In this case, it could be either one of two faint stars at the centre of the circle.