James Webb Space Telescope catches ancient galaxy in the act of explosive star birth

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The galaxy is one of the earliest active star-forming galaxies studied in detail by astronomers.

a spacecraft with a large gold hexagon on top in deep space
An illustration of the James Webb Space Telescope observing a galaxy in deep space. (Image credit: dima_zel/iStock/Getty Images)

The James Webb Space Telescope (JWST) continues to peer backwards through cosmic time, revealing the processes that created the universe as we see it today.

Astronomers have used the James Webb Space Telescope to stare through the dusty clouds of a distant star-forming galaxy to investigate its structure in fine detail. They discovered that the galaxy is in the midst of a starburst, an explosive surge in star formation possibly caused by a collision with another galaxy. 

Located at a distance of around 12 billion light-years away, the galaxy GN20 is one of the earliest active star-forming galaxies studied in detail thus far by astronomers. It also happens to be one of the most luminous dusty star-forming galaxies ever studied. 

Related: James Webb Space Telescope (JWST) — A complete guide

GN20 is located in a region of space called a galaxy overdensity or a protocluster. In these regions, galaxies will eventually group together to form a massive collection called a galactic cluster. 

The early galaxy, which was seen as it was when the 13.8 billion-year-old universe was just around 1.8 billion years old, is forming stars at a rate of around 1,860 times the mass of the sun each year. Clumpy molecular gas surrounds the galaxy expanding out to a diameter of around 46,000 light-years, and this star-forming matter is flattened into a giant rotating disk. 

Star-forming galaxies are surrounded by dense clouds of dust and gas that collapse in over-dense patches to form stars; these also make them difficult to investigate. This is because these clouds are adept at absorbing visible light, but infrared light has a much easier time slipping through this star-forming matter. That means the JWST, which was designed to see the universe in infrared wavelengths, is ideal for peering beyond these dusty veils to see deep into these galaxies. 

To study GN20 and unveil its properties, astronomers led by Spanish Astrobiology Center scientist Luis Colina used observations of this galaxy made by the JWST's Mid-Infrared Instrument (MIRI) between November 23 and 24, 2022. 

Composite image of GN20 displaying the UV emission (HST/F105W, blue), cold dust continuum (PdBI/880µm, lime), molecular gas (VLA CO(2-1), orange), and stellar (MIRI/F560W, purple) components of the galaxy.  (Image credit: Colina et al, 2023)

The astronomers found that the early star-forming galaxy has a concentrated bright nucleus of densely clustered stars at its core surrounded by a diffuse envelope of gas. This inner structure of GN20 is birthing stars at a rate of about 500 times the mass of the sun each year and has been doing so for a period of around 100 million years. 

The observations also showed this nucleus is under 2,600 light-years in diameter, while its gaseous envelope has a diameter of around 23,000 light-years. 

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The center of the gas is off-center in relation to GN20's dense nucleus of stars, implying that GN20 has recently undergone an encounter with another galaxy. This deformation in the gas envelope may have been the result of gravity tugging at it as the two galaxies passed each other, or it could be an artifact arising from a more permanent collision and merger between two galaxies. Interactions like this are often theorized to be the cause of intense periods of star formation in galaxies.

The team behind this research concluded that GN20 will eventually become a massive galaxy resembling those found in the local universe around the Milky Way with its bout of intense star formation eventually coming to an end leaving it inactive or quiescent. 

A pre-print version of the team's research is currently featured on arXiv.org.

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Robert Lea
Robert Lea
Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

5 Comments Comment from the forums
  • rod
    "Located at a distance of around 12 billion light-years away, the galaxy GN20 is one of the earliest active star-forming galaxies studied in detail thus far by astronomers. It also happens to be one of the most luminous dusty star-forming galaxies ever studied."

    Ref - Uncovering the stellar structure of the dusty star-forming galaxy GN20 at z=4.055 with MIRI/JWST, https://arxiv.org/abs/2304.13529, 26-April-2023. “…The stellar size of GN20 is larger by a factor of about 3-5 than known spheroids, disks, and irregulars at z∼4, while its size and low Sérsic index are similar to those measured in dusty, infrared luminous galaxies at z∼2 of the same mass. GN20 has all the ingredients necessary for evolving into a massive spheroidal quiescent galaxy at intermediate z: it is a large, luminous galaxy at z=4.05 involved in a short and massive starburst centred in the stellar nucleus and extended over the entire galaxy, out to radii of 4 kpc, and likely induced by the interaction or merger with a member of the proto-cluster.”

    https://lambda.gsfc.nasa.gov/toolbox/calculators.html, using this calculator, z=4.055, the age of universe at z=4.055, 1.533 Gyr, look back time distance to Earth today, 12.188 Gyr or some 12 billion light years from Earth. The radius of the universe when GN20 first appeared is about 4.75 Gly so the diameter of the universe then, about 9.5 Gly across compared to the present value used, about 93 Gly for the CMBR redshift of about 1100. What is interesting, GN20 comoving radial distance today is 24 Gly away from Earth. Space expands at about 1.69 x c velocity (H0 = 69 km/s/Mpc) where GN20 could be today (not visible from Earth today). So, when GN20 first appeared according to the BB model, the universe size only about 9.5 Gly diameter and now today, if it still exists, sits in space expanding 1.69 x c velocity or a bit faster where the universe diameter today is some 93 Gly or perhaps more. Some important concepts I feel should be kept in mind when reading about galaxy evolution reports like this.
    Reply
  • Atlan0001
    Rod,

    12.188 Gyr or some 12 billion light years from Earth, is a lot of turns, a lot of bends around the gravity-light cone of the spacetime Abyss. A hell of a lot of turns and bends detouring around the turns and bends of the cone of the Abyss.

    Now, Rod, I want to ask you what would be the straight-line distance for a continuously powered ship at a continuous 1-earth-grav of acceleration, say the wormhole-tunnel straight-line (as straight-line can get in the universe) distance, straight through the center of the Abyss's cone to that precise spacetime coordinate location, it's spatial positional location, where and as it is today in time (time here on Earth), 12.188 Gyrs later in time than 12 billion light years from Earth?

    Rod, you know I really don't expect a measurement. I just wanted to get the 'Alice in Wonderland: Through the Looking Glass' rhetorical question out regarding positional placement today in time of that warp bubble of space. It's the kind of quantum mechanical-like question that the principle of uncertainty forbids anything like a real answer to.
    Reply
  • rod
    Atlan0101 said:
    Rod,

    12.188 Gyr or some 12 billion light years from Earth, is a lot of turns, a lot of bends around the gravity-light cone of the spacetime Abyss. A hell of a lot of turns and bends detouring around the turns and bends of the cone of the Abyss.

    Now, Rod, I want to ask you what would be the straight-line distance for a continuously powered ship at a continuous 1-earth-grav of acceleration, say the wormhole-tunnel straight-line (as straight-line can get in the universe) distance, straight through the center of the Abyss's cone to that precise spacetime coordinate location, it's spatial positional location, where and as it is today in time (time here on Earth), 12.188 Gyrs later in time than 12 billion light years from Earth?

    Rod, you know I really don't expect a measurement. I just wanted to get the 'Alice in Wonderland: Through the Looking Glass' rhetorical question out regarding positional placement today in time of that warp bubble of space. It's the kind of quantum mechanical-like question that the principle of uncertainty forbids anything like a real answer to.
    Very interesting Atlan0101. You said, "I just wanted to get the 'Alice in Wonderland: Through the Looking Glass' rhetorical question out regarding positional placement today in time of that warp bubble of space."

    Einstein GR and the metric developed for expanding space used in the cosmology calculators, clearly define that position today relative to Earth. It is the comoving radial distance which I show for GN20 is some 24 billion light years distance from Earth. We cannot see GN20 sitting there in that space and position today :) Likewise observing GN20 in a universe only 9.5 billion light years in diameter when GN20 first appears after BB event compared to the universe size in BB model today, is another item I know I cannot see using my two telescopes :) Lesson I learned here. I must be flexible when explaining how gas clouds can evolve into galaxies and people :)
    Reply
  • Atlan0001
    I'm not disputing a thing you have to say, Rod. I don't understand half what you say but I do follow you along on the forum, because you study what is in front of you, even if what you see isn't what is there at that distance and may never have been there at that distance but comes from somewhere else, like a synthesis or coalescence, or composite dimensionality, the collapsed constant of Horizon being ultimate. It's real alright, but probably not there, probably never was there, in either the space or time of the level of life zone Stephen Hawking referred to as continuous without end, therefore an infinity of Flatland level if only life remains in, on, that level of "Many Worlds" or "many universes" as I have it.

    I'm not saying you're looking at less. I'm trying to tell you, the general 'you", that is, that you may be -- just might be -- observing far more than you think you are witnessing through the eye pieces of your scopes, and so might the Webb and Hubble, and others, be picking up on. A far greater dimensionality than any but a few might actually see from the picture.

    I will go further; try to put it together more, elsewhere.
    Reply
  • rod
    Atlan0101 said:
    I'm not disputing a thing you have to say, Rod. I don't understand half what you say but I do follow you along on the forum, because you study what is in front of you, even if what you see isn't what is there at that distance and may never have been there at that distance but comes from somewhere else, like a synthesis or coalescence, or composite dimensionality, the collapsed constant of Horizon being ultimate. It's real alright, but probably not there, probably never was there, in either the space or time of the level of life zone Stephen Hawking referred to as continuous without end, therefore an infinity of Flatland level if only life remains in, on, that level of "Many Worlds" or "many universes" as I have it.

    I'm not saying you're looking at less. I'm trying to tell you, the general 'you", that is, that you may be -- just might be -- observing far more than you think you are witnessing through the eye pieces of your scopes, and so might the Webb and Hubble, and others, be picking up on. A far greater dimensionality than any but a few might actually see from the picture.

    I will go further; try to put it together more, elsewhere.
    "...even if what you see isn't what is there at that distance and may never have been there at that distance but comes from somewhere else..."

    Atlan0101, knowing the distance to an object in astronomy is a real issue and part of the science. An incorrect distance or unknowable distance can cause headaches :) Here is the link for the GN20 paper used, https://arxiv.org/pdf/2304.13529.pdf, it is a 7-page PDF report. I found 14 references to *arcsec* used. Without knowing distances, such angular measurements in the paper, IMO is showing nothing at all but likely incorrect values and measurements for sizes, masses, energy levels, etc. Using arcsec measurements is critical to astronomy. If there is some other dimensions or multiverse surrounding those arcsec values, science remains to show this IMO. GN20 is a good paper I feel but some aspects like the original size of the universe when GN20 appears and where GN20 is today using the comoving radial distance, is not something observable directly like seeing the Galilean moons move around Jupiter.
    Reply