Galaxy light show

This Hubble Picture of the week features NGC 1672, a barred spiral galaxy located 49 million light-years from Earth in the constellation Dorado. This galaxy is a multi-talented light show, showing off an impressive array of different celestial lights. Like any spiral galaxy, its disc is filled with billions of shining stars that give it a beautiful glow. Along its two large arms, bubbles of hydrogen gas are made to shine a striking red light by the powerful radiation of newly-forming stars within. Near to the centre lie some particularly spectacular stars; newly-formed and extremely hot, they are embedded in a ring of hot gas and are emitting powerful X-rays. And in the very centre sits an even more brilliant source of X-rays, an active galactic nucleus created by the heated accretion disc around NGC 1672’s supermassive black hole; this makes NGC 1672 a Seyfert galaxy.

But a highlight of this image is the most fleeting and temporary of these lights: supernova SN 2017GAX, visible in just one of the six Hubble images that make up this composite image. This was a Type I supernova caused by the core-collapse and subsequent explosion of a giant star, going from invisibility to a new light in the sky in just a matter of days. In that image from later that year, the supernova is already fading, and so is only just visible here as a small green dot, just below the crook of the spiral arm on the right side. In fact this was on purpose, as astronomers wanted to look for any companion star that the supernova progenitor may have had — something impossible to spot beside a live supernova! Look for it as a small green dot, just below the crook of the spiral arm on the right side. If you can't find it, try looking at this collage.

Recently, NGC 1672 was also among a crop of galaxies imaged with the NASA/ESA/CSA James Webb Space Telescope, showing the ring of gas and the structure of dust in its spiral arms. A Hubble image was also released previously in 2007.

[Image Description: A spiral galaxy with an oval-shaped disc. Two large arms curve out away from the ends of the disc. The arms are traced by bright pink patches where stars are forming and by dark reddish threads of dust. The core is very bright and star-filled. Some large stars appear in front of the galaxy. Directly under the point where the right arm joins the disc, a fading supernova is visible as a green dot.]