A chance alignment in Lupus

The subject of today’s NASA/ESA Hubble Space Telescope Picture of the Week is the stunning spiral galaxy NGC 5530. NGC 5530 is situated 40 million light-years away in the constellation Lupus (The Wolf). This galaxy is classified as a ‘flocculent’ spiral, meaning that its spiral arms are patchy and indistinct.

While some galaxies have extraordinarily bright centres where they host a feasting supermassive black hole, the bright source near the centre of NGC 5530 is not an active black hole but instead a star within our own galaxy, only 10 thousand light-years from Earth. This chance alignment gives the appearance that the star is at the dense heart of NGC 5530.

If you had pointed a backyard telescope at NGC 5530 on the evening of 13 September 2007, you would have seen another bright point of light adorning the galaxy. That night, Australian amateur astronomer Robert Evans discovered a supernova, named SN 2007IT, by comparing NGC 5530’s appearance through the telescope to a reference photo of the galaxy. While it’s remarkable to discover even one supernova using this painstaking method, Evans has in fact discovered more than 40 supernovae this way! This particular discovery was truly serendipitous: it’s likely that the light from the supernova had completed its 40-million-year journey to Earth just days before the explosion was discovered. 

[Image Description: A spiral galaxy, seen tilted at a slight angle, on a dark background of space. It glows softly from its centre, throughout its disc out to the edge. The disc is a broad swirl of webs of dark reddish dust and sparkling blue patches where stars have formed. Atop the centre of the galaxy there is a star that appears very large and bright with four spikes emanating from it, because it is relatively close to Earth.]