Newly-discovered galaxy ‘mirrors the early Milky Way’
A galaxy nine billion light years away discovered by NASA‘s James Webb Space Telescope ‘mirrors the early Milky Way’, a new study reveals.
Dubbed ‘the Sparkler galaxy’, it’s swallowing up the globular clusters and satellite galaxies that surround it to gradually grow bigger and bigger.
Globular clusters are extremely luminous clusters of tens of thousands to millions of stars, all bound together by gravity.
The Sparkler galaxy appeared as a small orange line in the first image from the James Webb telescope released in July last year.
Researchers announced the discovery the galaxy later in 2022 but it’s only now that they’ve learnt more about its composition.
The Sparkler galaxy appeared as a small orange curve in the first image from the James Webb telescope released in July last year (yellow rectangle)
This image shows an artist impression of our Milky Way galaxy in its youth. Five small satellite galaxies, of various types and sizes, are in the process of being accreted into the Milky Way
The new study has been conducted by researchers in Australia and California and published in Monthly Notices of the Royal Astronomical Society.
The Sparkler galaxy
– 9 billion light years away
– Surrounded by globular clusters and satellite galaxies
– Found in the constellation of Volans in the southern sky
– Detected by NASA’s James Webb Space Telescope
‘We appear to be witnessing, first hand, the assembly of this galaxy as it builds up its mass – in the form of a dwarf galaxy and several globular clusters,’ said study author Professor Duncan Forbes at Swinburne University in Melbourne.
‘We are excited by this unique opportunity to study both the formation of globular clusters, and an infant Milky Way, at a time when the universe was only one third of its present age.’
The galaxy got its name for the compact objects appearing as small yellow-red dots surrounding it, referred to by the researchers as ‘sparkles’.
The team posited that these sparkles could either be young clusters actively forming stars – born three billion years after the Big Bang at the peak of star formation – or old globular clusters.
Globular clusters are ancient collections of stars from a galaxy’s infancy and contain clues about its earliest phases of formation and growth.
The researchers studied the Sparkler galaxy located in Webb’s First Deep Field – the first operational image taken by the James Webb Space Telescope, unveiled in July 2022
In this snippet of a section of the James Webb image, the Sparkler can be seen in the top left-hand corner – a small orangey line
Globular clusters: A type of star cluster
As the name suggests, star clusters are groups of hundreds to millions of stars that share a common origin, all gravitationally bound for as long as several billions of years.
There are two types of star clusters – open and globular. Globular clusters are dense balls of about one million ancient stars, all bound by gravity. Open clusters are much younger and smaller than globular clusters.
According to experts at Penn State University, open clusters are usually a few tens of millions or hundreds of millions of years old, while globular clusters are typically about 12 billion to 13 billion years old.
And because it is 9 billion light years away, this means we are seeing it as it was nine billion years ago, when the universe was only four-and-a-half billion years old.
For the study, researchers examined the age and metallicity distribution of a dozen of the compact star clusters surrounding the Sparkler.
This let them determine that they resemble younger versions of the clusters that now surround our galaxy, the Milky Way.
Several have old formation ages and are metal-rich similar to those seen in the bulge of the Milky Way and so are likely to be globular clusters.
Although the Sparkler is currently only 3 per cent the mass of the Milky Way, it is expected to grow over time to match the Milky Way’s mass.
The team will need deeper imaging to detect more clusters and satellites around the Sparkler.
The James Webb’s first image was released by US President Joe Biden on July 11, a day before the others.
It shows the Sparkler as just one of many galaxies bound together by gravity in a so-called ‘galaxy cluster’ called SMACS 0723.
According to NASA, SMACS 0723 has a gravitational pull so powerful that it warps both space-time and the path that light subsequently travels through it.
Webb’s increased resolution and sensitivity unveiled the tiny ‘sparkler’ dots surrounding the galaxy for the first time in its first Deep Field image
Because of this, bright white galaxies are warping and stretching the light from the more distant galaxies, making them seem elongated, almost banana-shaped.
The combined mass of SMACS 0723 operates as a gravitational lens and, according to NASA, ‘magnify and distort the light of objects behind them, permitting a deep field view into both the extremely distant and intrinsically faint galaxy populations’.
Webb’s NIRCam, which captures light from the edge of the visible through the near infrared range of the electromagnetic spectrum, brought distant galaxies into sharp focus in the image.
The James Webb Telescope: NASA’s $10 billion telescope is designed to detect light from the earliest stars and galaxies
The James Webb telescope has been described as a ‘time machine’ that could help unravel the secrets of our universe.
The telescope will be used to look back to the first galaxies born in the early universe more than 13.5 billion years ago, and observe the sources of stars, exoplanets, and even the moons and planets of our solar system.
The vast telescope, which has already cost more than $7 billion (£5 billion), is considered a successor to the orbiting Hubble Space Telescope
The James Webb Telescope and most of its instruments have an operating temperature of roughly 40 Kelvin – about minus 387 Fahrenheit (minus 233 Celsius).
It is the world’s biggest and most powerful orbital space telescope, capable of peering back 100-200 million years after the Big Bang.
The orbiting infrared observatory is designed to be about 100 times more powerful than its predecessor, the Hubble Space Telescope.
NASA likes to think of James Webb as a successor to Hubble rather than a replacement, as the two will work in tandem for a while.
The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.
It circles the Earth at a speed of about 17,000mph (27,300kph) in low Earth orbit at about 340 miles in altitude.