Today’s Image of the Day from the European Space Agency features a stunning view of the spiral galaxy NGC 1309 captured by the Hubble Space Telescope.
The galaxy, located about 100 million light-years from Earth in the constellation Eridanus, shines with bluish stars and trails of dusty gas.
The real fascination lies not just in how NGC 1309 looks – it’s what happened there that keeps astronomers coming back.
The galaxy has been a familiar subject for Hubble, appearing in images released in both 2006 and 2014. That continued interest isn’t just because it’s photogenic.
NGC 1309 is a site of rare astronomical events that have helped researchers understand what happens when stars die, and in one case, what happens when they don’t quite finish the job.
Hundreds of galaxies surround NGC 1309
Hubble’s newest look at NGC 1309 captures more than just one galaxy. As ESA noted, countless distant galaxies are visible in the background of the image.
But one sharp point of light stands out near the top of the frame. It’s not a galaxy, but a nearby star from our own Milky Way, just a few thousand light-years away.
“This stunning Hubble image encompasses NGC 1309’s bluish stars, dark brown gas clouds and pearly white centre, as well as hundreds of distant background galaxies,” noted ESA.
“Nearly every smudge, streak and blob of light in this image is an individual galaxy. The only exception to the extragalactic ensemble is a star, which can be identified near the top of the frame by its diffraction spikes.”
The unusual story of NGC 1309
Even though the view is crowded, all eyes are on NGC 1309. This galaxy gained attention after two significant explosions lit it up in the past few decades. The first, a textbook Type Ia supernova named SN 2002fk, occurred in 2002.
These types of supernovae are known for being reliable “standard candles” that help astronomers measure cosmic distances. They happen when a white dwarf – the leftover core of a dead star – gets pushed past its limit and explodes.
That first explosion was expected. The second one, though, was not.
A supernova that left something behind
In 2012, Hubble detected a second supernova in NGC 1309 – SN 2012Z. This one threw scientists a curveball. On the surface, it looked like another Type Ia event, but its brightness didn’t quite measure up. It turned out to be part of a lesser-known category called Type Iax supernovae.
Unlike typical Type Ia explosions, SN 2012Z didn’t tear the white dwarf completely apart. What was left behind surprised astronomers: a “zombie star.”
Instead of fading into the background, the star remained – and it actually became brighter after the explosion. That’s not something astronomers were expecting to see.
This discovery made NGC 1309 the site of something that had never been captured before: the exact white dwarf that triggered a supernova, seen in images taken before the explosion.
Usually, supernovae are identified after the fact, based on the light they release. But in this case, the star was already in Hubble’s earlier images of the galaxy. That allowed scientists to link the before-and-after views in a way they’d never been able to do.
Why these explosions matter
Studying supernovae helps astronomers learn about the life cycles of stars, and how the elements created in those explosions spread through galaxies.
Type Ia supernovae, in particular, have been crucial for measuring how fast the universe is expanding. But Type Iax events like SN 2012Z add a wrinkle to that story.
These smaller explosions don’t follow the usual rules. They’re dimmer, take longer to unfold, and – as SN 2012Z revealed – they might not mark the end of a star’s life.
Ultimately, weaker explosions are less reliable for measuring distances in space. But they offer something different: a look at what could happen when a supernova doesn’t finish the job.
Observing a white dwarf that somehow survives its own explosion gives scientists a chance to rethink their models. Maybe some stars don’t die as completely as once thought. Maybe there’s a middle ground between a full explosion and a quiet fade.
Hubble’s long memory pays off
Thanks to its sharp vision and longevity, the Hubble Space Telescope has been able to watch NGC 1309 across decades. The long record made it possible to notice changes and connect the dots between past and present.
Even though newer telescopes like the James Webb Space Telescope are joining the game, Hubble still has a key role.
Hubble’s deep image of NGC 1309 is a map of astronomical history – and in this case, a rare chance to catch a supernova before and after its big moment.
Image Credit: ESA
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