Hubble telescope reveals Andromeda galaxy’s star formation has been fading for 500 million years
A new study using NASA’s Hubble Space Telescope has found that star formation in the Andromeda galaxy has been declining for 500 million years, with a particularly steep drop over the past 40 million years, offering the.
A study using NASA's Hubble Space Telescope found that star formation in the Andromeda galaxy (M31) has been declining for 500 million years, with a particularly steep drop over the past 40 million years. Most of the slowdown is attributed to decreasing activity in a large ring structure within the galaxy, according to NASA.
Star formation in the Andromeda galaxy has been declining for 500 million years, with the slowdown steepening sharply in the last 40 million years, according to a new study based on data from NASA’s Hubble Space Telescope. Researchers traced the fading activity across the galaxy, finding that most of the decline is concentrated in a large ring structure within Andromeda. The study also examined regions near the dwarf galaxy M32, where star formation rates were lower than elsewhere in Andromeda. The findings offer the clearest long-term view yet of how a major galaxy’s star birth can wind down. A century after Edwin Hubble first proved Andromeda was a separate galaxy, it continues to challenge assumptions about galactic evolution.
Hubble reveals Andromeda’s star birth has been fading for half a billion years
Star formation in the Andromeda galaxy has been slowing for 500 million years, according to a new study based on data from NASA’s Hubble Space Telescope. The decline became especially steep in the last 40 million years. Researchers traced the fading activity across the galaxy, producing what they describe as the most detailed look yet at how a major galaxy winds down its stellar birth rate. Most of the slowdown is attributed to decreasing activity within a large ring structure in Andromeda, according to NASA. The findings offer a rare, high-resolution view of a process that will eventually transform a bustling spiral galaxy into a quieter, less luminous system.
How researchers traced the slowdown across the galaxy
To trace the slowdown, researchers turned to the Panchromatic Hubble Andromeda Southern Treasury survey, a dataset from the Hubble Space Telescope, according to the team. They examined star formation activity across the galaxy and found that most of the decline is concentrated in a large ring structure within Andromeda, according to NASA — a detail the agency described with low confidence. The team also looked at the region near the dwarf galaxy M32, where star formation rates were lower than elsewhere in Andromeda, the researchers reported. The findings suggest the ring’s fading activity is the primary driver of the galaxy’s overall decline.
A century after Hubble’s discovery, Andromeda still yields surprises
A century ago, Edwin Hubble proved that the fuzzy patch then called the Andromeda Nebula was not a cloud within the Milky Way but a separate galaxy — a discovery that redrew the map of the universe. Today, the galaxy that bears his name remains the nearest large spiral to our own, close enough for telescopes like Hubble to resolve individual stars. That proximity makes M31 a uniquely detailed laboratory for studying how galaxies evolve over time. Researchers using the space telescope have now traced a steady decline in star formation across Andromeda over the past 500 million years, with the drop accelerating sharply in the last 40 million years. What is driving the slowdown is not yet clear. The cause remains under investigation.
Star formation in the Andromeda galaxy (M31) began to decline.
The decline in star formation in Andromeda became especially steep.
What the fading star formation means — and what remains unknown
The findings add to a growing picture of how large spiral galaxies evolve over time. Andromeda’s prolonged decline in star formation suggests that even major galaxies can experience extended quiet periods, not just sudden bursts or shutdowns. This raises questions about what forces govern such long-term changes.
The specific mechanism driving the decline remains unknown. Researchers have not identified whether it is caused by gas depletion, interactions with neighbouring galaxies, or internal dynamics. The current star formation rate in Andromeda is not provided in the study, so it is unclear how close the galaxy is to becoming dormant. Whether the process will eventually halt star formation entirely is also an open question. Without further data, the future of Andromeda’s stellar birth remains uncertain.
Frequently asked questions
Is star formation in the Andromeda galaxy declining?
A study using data from NASA's Hubble Space Telescope found that star formation in the Andromeda galaxy (M31) has been declining for about 500 million years. The decline became especially steep in the last 40 million years, according to NASA and researchers.
When did star formation in Andromeda start to decline?
The decline in star formation in Andromeda began about 500 million years ago. It became especially steep in the last 40 million years, according to NASA and researchers.
What telescope data was used for the Andromeda star formation study?
The study used data from NASA's Hubble Space Telescope. Researchers also said it used data from the Panchromatic Hubble Andromeda Southern Treasury survey, though this is attributed to them with low confidence.
What is causing the decline in star formation in Andromeda?
According to NASA (with low confidence), most of the slowdown in star formation is attributed to decreasing activity in a large ring structure within the galaxy. Researchers also noted that star formation activity near the dwarf galaxy M32 was lower compared to other regions of Andromeda.
What did researchers find about star formation near M32 in Andromeda?
The study used data from NASA's Hubble Space Telescope, and researchers said it was from the Panchromatic Hubble Andromeda Southern Treasury survey. They examined star formation activity near the dwarf galaxy M32, finding it lower there than in other regions of Andromeda.
Compiled from reporting by 8 independent outlets. How we source our reporting.
