The Milky Way is even bigger than we thought, a new study has revealed.
Scientists from the European Space Agency spotted the aftermath of three bright explosions echoing through the outer spiral arms of our galaxy.
By measuring the distance to those echoes, they found that the outer arms are actually 10 per cent further away than previously believed.
‘We usually model the Milky Way’s outer arms indirectly based on what we know of how our galaxy rotates, but doing it this way leaves room for error,’ explained Beatrice Vaia of Istituto Nazionale di Astrofisica (INAF), Italy, who led the research.
‘Instead, we did something new.
‘We looked at the aftermath of three cosmic explosions that took place in far more distant galaxies.
‘These explosions flung out X–rays that echoed through several of the Milky Way’s outer arms – and we measured the distances to these echoes directly.’
The findings could help to shed light on the structure of our galaxy’s outer regions.
Scientists from the European Space Agency spotted the aftermath of three bright explosions echoing through the outer spiral arms of our galaxy. By measuring the distance to those echoes, they found that the outer arms are actually 10 per cent further away than previously believed
While our solar system sits within the Milky Way, scientists still don’t know much about its structure.
However, this is changing, as new telescopes offer fresh views of our galaxy.
For example, scientists were previously unsure if the Milky Way had two or four arms.
In 2020, observations by the Gaia space telescope confirmed that the answer is four.
In their new study, the team used the XMM–Newton and NASA’s Chandra X–ray space telescopes to study the gamma–ray bursts thrown out by three bright explosions in the outer spiral arms of the Milky Way.
By studying how these bursts slowly expanded over time, the team was able to pinpoint the distance of the scattering dust grains.
As these lie in clouds within the arms of our galaxy, the researchers could then directly measure the distance of the arms.
The results revealed that two of the Milky Way galaxy’s arms – Outer Scutum–Centaurus Arm and Outer Arm – lie up to 10 per cent further away than we thought.
By studying how these bursts slowly expanded over time, the team was able to pinpoint the distance of the scattering dust grains. As these lie in clouds within the arms of our galaxy, the researchers could then directly measure the distance of the arms
‘This finding is a great example of how ESA’s longer–standing missions – such as XMM–Newton, which launched in 1999 – still have a hugely important role to play in exploring the Universe,’ said Erik Kuulkers, ESA XMM–Newton project scientist.
‘Now in its third decade, XMM–Newton continues to return a steady stream of groundbreaking science on everything from the brightest–ever GRB, to stars being shredded by black holes, to X–ray snapshots of Mars.
‘It’s even more exciting when missions team up, as they did here.
‘Together, they can reveal huge amounts about the skies around us.’
