It was an active final day at the First Science Results from JWST conference at the Space Telescope Science Institute in Baltimore, US, where discussion turned to some incredible observations of quasars above redshift 6, showing them as they existed more than 12.7 billion years ago.

As the compact cores of galaxies with extremely active supermassive black holes, we know that quasars can shine many times brighter than their host galaxy. In his presentation, John Silverman of the University of Tokyo described how data from the JWST’s CEERS (Cosmic Evolution Early Release Science) survey is following up on a dozen high-redshift quasars originally identified by the Subaru Telescope on Mauna Kea.

Throughout the conference, astronomers have joked that high redshift no longer means what it used to mean. Before the JWST came along, high redshift for the Hubble Space Telescope meant resolving the host galaxies of quasars out to about redshift 2, or roughly 10 billion years in the past. Now, the JWST is resolving the structures of host galaxies around quasars at redshift 6 (almost 12.7 billion years ago).

Much happened in the universe between redshifts 2 and 6, and astronomers are keen to see if the ratio of the mass of a supermassive black hole at the centre of a galaxy relative to the mass of its host galaxy (or more specifically the stellar mass of the galaxy’s bulge) still holds at the highest redshifts. The answer will tell us about the conditions under which supermassive black holes and galaxies formed, and how they affected each other’s growth.

The mass ratio between a supermassive black hole and the bulge of a galaxy around it is 1:200, with this value believed to be connected to feedback from the black hole in the form of outflows of radiation spewing out as it accretes matter. The relationship was first quantified by observations with the Hubble Space Telescope in the 1990s, with Silverman calling it “fundamental.”

It turns out that high redshift galaxies do indeed also stick to this relation. Silverman said that astronomers have targeted redshift 6 because it’s at this redshift that simulations of galaxies tend to differ the most. What astronomers really need is some hard and fast data to input into the simulations, and the JWST has been happy to oblige.

The typical galaxy hosting a quasar at this redshift is just 8% as luminous as the quasar. However, it’s actually possible to take the glare of a quasar out of the image – since the quasar itself appears point-like, it manifests as diffraction spikes that can be removed by a point spread function.

The JWST finds the galaxies to be fairly compact and disc-shaped, with surprisingly well-defined spiral arms and central bars just a billion years after the Big Bang. In her talk, Madeline Marshall, of NRC Herzberg in Victoria, Canada, discussed the first high-redshift quasar results from the JWST’s Near-Infrared Spectrometer (NIRSpec), finding these black holes to weigh billions of solar masses, and the mass of their host galaxies to be in the region of hundreds of billions, therefore seeming to maintain the mass ratio observed at lower redshift.

How exactly black holes grew to be so massive so early in the universe is still under debate, but hopefully the JWST will start to provide some answers. Just to give an indication of the telescope’s power, the JWST’s resolution is so fine that some of the quasar images show companion galaxies merging or interacting with the main galaxy, sporting tidal tails and bursts of star-formation at a rate of 30–50 solar masses per year.

Exoplanets and protoplanetary discs

Earlier in the day, exoplanets and protoplanetary discs came under the spotlight. Olivier Berné of the Institut de Recherche en Astrophysique et Planétologie in Toulouse revealed a solution to how planets can form in the ultraviolet-radiation-rich environments of large star clusters.

These star clusters produce their fair share of hot, young, massive stars that emit lots of ultraviolet radiation that ought, in principle, to erode protoplanetary discs around neighbouring lower mass stars. Berné reported how JWST astronomers, working with colleagues from the Atacama Large Millimeter/submillimeter Array, have observed the chemistry of these vulnerable discs and discovered a warm envelope of molecular gas surrounding them.

The envelopes are rich in polycyclic aromatic hydrocarbons, which have a strong infrared spectral signature that stands out to the JWST. They also have a high ultraviolet opacity, so they are able to block a lot of the harmful ultraviolet from outside a disc, protecting the early stages of planet formation.

Inside a planet-forming disc

One protoplanetary disc where planet-formation has proceeded quite far is PDS 70. It hit the news in 2018 and 2021 when astronomers using ALMA were able to image rings in PDS 70’s disc that appear to have been carved out by two young planets.

Giulia Perotti of the Max Planck Institute for Astronomy in Heidelberg revealed how the JWST can now measure chemistry within the inner region of PDS 70’s protoplanetary disc. It appears to be enriched with small dust grains that have been thermally processed, possibly by outbursts from the young star. The inner disc, meanwhile, is warped, possibly from the influence of another, unseen planet. Chemically, water and oxygen have also been detected in the disc. PDS 70 continues to be our best-studied example of planets forming within a disc of gas and dust.

WASP atmospheres

Meanwhile, Kevin Stevenson of Johns Hopkins Applied Physics Laboratory updated delegates on the JWST’s observations of the atmospheres of older exoplanets. First, he recounted the space telescope’s observations of WASP-39b – a “hot Jupiter” 700 light-years away.

These observations were made as WASP-39b was transiting its star, with some of the star’s light being absorbed by atoms and molecules in the planet’s atmosphere as it passed through. Using this “transmission spectroscopy”, the JWST detected carbon monoxide, potassium, sodium and water in the atmosphere of WASP-39b, as well as sulphur dioxide, which is a product of photochemistry.

It’s the first time photochemical processes, in which radiation from the star alters molecules, have been detected on any exoplanet. The absence of a strong methane line at 3.3 microns is also evidence that photochemistry is transforming methane into other molecular species.

Stevenson then went on to preview results from another hot Jupiter – the planet WASP-43b, which lies 284 light-years away. When the JWST’s predecessor, the Spitzer Space Telescope, observed WASP-43b it could not detect any thermal emission from the planet’s night-side, which means it must be cold, beyond the limits of Spitzer to detect.

Stevenson revealed that the JWST had now detected this faint thermal emission, and – although he couldn’t give details – he described how making this measurement and measuring the temperature of the night-side would allow scientists to better constrain the properties of the tidally locked planet’s atmosphere.

Tantalizing TRAPPIST-1

We also heard new findings from the TRAPPIST-1 planetary system, which consists of seven planets in orbit around a red dwarf star 40 light-years away. Björn Benneke of the University of Montreal revealed that the JWST had performed reconnaissance of the atmospheres of some of the worlds of TRAPPIST-1.

While he wasn’t able to say anything yet about what the JWST had positively detected in their atmospheres, he did reveal that the seventh planet, TRAPPIST-1g, probably does not have a thick atmosphere rich in hydrogen. This would seemingly rule out it being a so-called ‘Hycean’ world, consisting of an ocean kept warm by a thick swathe of hydrogen. Since planet ‘g’ is at the very outer edge of TRAPPIST-1’s habitable zone, it might mean that without a thick insulating atmosphere, TRAPPIST-1g could be too cold to be habitable to life as we know it.

The three-day conference was an exciting preview of how the JWST is beginning to transform astronomical research and allow us to detect things that were completely beyond astronomers until now. Sometimes the conference presentations were frustratingly light on details – many said they’d have more to say next year, particularly at the 241st meeting of the American Astronomical Society (AAS) on 8–12 January in Seattle.

We have to remember, though, that the JWST has only been collecting data for barely six months. Given the complexity of both the telescope and the information it is collecting, astronomers are making sure to take care with their findings. If the preliminary results from this first JWST science conference are any indication, then the next few years could be some of the most exciting times ever for astrophysicists, cosmologists and planetary scientists.

The life and death of stars; setting sights on minor asteroidal and cometary bodies in our solar system; the oldest planets in the universe; and the secrets of supernovae – a rollercoaster ride of new discoveries was revealed on day two of the “First Science Results from JWST” conference, held at the Space Telescope Science Institute in Baltimore, US.

Stellar nurseries on Cosmic Cliffs

One of the first images to be released from the JWST in July this year was that of the “Cosmic Cliffs” – a section of the Carina star-forming nebula located about 8500 light-years away. Previously imaged by the Hubble Space Telescope, the so-called cliffs are made of molecular gas encircling a giant bubble blown in the nebula by the stellar winds and ultraviolet light of five luminous O-type stars, which are the hottest and most massive type of stars to exist. Embedded within the wall of gas are nascent stars. As astronomer Megan Reiter of Rice University explained, the JWST has now identified 24 new outflows from young stars that are still growing by accreting matter from their surroundings. By tracing these outflows, Reiter and her colleagues are able to locate the sites of star formation within the nebula.

The aim of their observations is to better understand what is triggering star formation in the nebula, said Reiter. Do the winds of the five O-type stars compress the gas in the Cosmic Cliffs on the edge of the bubble and trigger star formation that way, or are the knobbly “cliff tops”, where some young stars are forming, simply made from denser regions of gas that have survived the erosional onslaught of the ultraviolet radiation? As of now, more observations are needed, but the JWST is more equipped than Hubble was to answer these question in the future.

Icy building blocks

Young stars are surrounded by proto-planetary discs, where all kinds of complex carbon chemistry can occur, depending on the distance from the star (and hence the temperature), as well as the density of the gas. Yao-Lun Yang of RIKEN in Japan and the University of Virginia, US, showed how the JWST observations of a young protostar catalogued as IRAS 15398-3359 revealed the spectral signature of ices containing complex organic molecules in the disc around the star.

The JWST’s mid-infrared spectrum of the star contains unprecedented detail, showing molecules such as ethanol, methanol, methane and dimethyl embedded within ices in the disc. These molecules are potentially the building blocks for all kinds of carbon chemistry, including life. “The crazy thing to us is that there is so much detail [in the spectrum],” said Yang.

Delayed detonations

Things got explosive with Chris Ashall’s presentation on a type Ia supernova, SN 2021aefx, which exploded in 2021 in the galaxy NGC 1566, located about 33 million light-years away. Type Ia supernovae mainly involve the death of a white dwarf star, but there are several permutations that could give rise to such a supernova – from the destruction of a single white dwarf to a binary merger. There are also questions about whether the explosion detonates in the core of the white dwarf, or whether it is sparked in its outer shell before travelling into the core.

Ashall, of Virginia Tech, talked about how the key to figuring out the dynamics of the SN 2021aefx explosion was in the JWST identifying the location of certain critical ionized elements in the supernova remnant. The JWST was able to detect emissions from doubly ionized cobalt that had decayed from quantities of nickel-56 that had formed in the violence of the supernova explosion. The location of the cobalt, and hence the nickel, was not at the centre of the explosion, but offset from the centre in the outer layers, whereas the JWST did see an abundance of argon at the centre.

There were also spectral lines of nickel-58, which forms in high density regions, suggesting that the white dwarf that exploded had a mass of at least 1.2 times the mass of the Sun – this is nearly as massive as a white dwarf can get (the Chandrasekhar limit of 1.44 solar masses). Comparing the location of the cobalt, argon and nickel lines, Ashall and his colleagues saw that it matched simulations of delayed detonation supernova, wherein a single white dwarf accreting matter from a companion star experiences a wave of intense internal heating that reverberates around the star before it explodes.

Water on the main

Minor bodies in our own solar system were also under the spotlight, particularly the weird objects that astronomers call “main belt comets”. These are objects that behave like icy comets, with tails and comae – but which leisurely orbit around the Sun, in the main asteroid belt between Mars and Jupiter, along with myriad inert rocky asteroids. Their origins and the mechanisms that drive their pseudo-cometary behaviour are still a mystery, one that the JWST has now shed a little light on.

Michael Kelley of the University of Maryland reported on the JWST’s observations of the main belt comet 238P/Read, detecting the spectral signature of outflows of water vapour, but no carbon dioxide, the absence of which is considered unusual. The lack of carbon dioxide is a big clue as to the origin of this particular main belt comet. Either the carbon dioxide was baked out of the comet after it arrived in the asteroid belt, or it never had carbon dioxide in the first place.

“We think it’s more likely that carbon dioxide was never accreted,” said Kelley. This suggests that 238P/Read represents a new class of cometary body that has become trapped in the asteroid belt.

The oldest ones

The solar system formed about 4.5 billion years ago, but the universe is 13.8 billion years old. How soon after the Big Bang could planets form around stars? One place to try and find the answer is globular clusters, which are ancient, having formed 12–13 billion years ago. Matteo Correnti of STScI, spoke about sifting through the stars of one globular cluster known as 47 Tucanae, in search of white dwarfs with anomalous infrared excesses. A white dwarf is the remains of a Sun-like star that has expired, puffing off its outer layers into deep space to leave an inert, hot core. The fluctuating gravitational tides that occur during this slow process of star death can disrupt orbiting planetary systems, smashing them apart and resulting in planetary debris falling onto the surface of the white dwarf. This has actually been observed on younger white dwarfs in the Milky Way, and the planetary debris has a signature in the infrared wavelengths that the JWST observes at.

The stars of 47 Tucanae are calculated to have formed 13.06 billion years ago, so any planets that once existed around one of these stars that became a white dwarf will also be 13.06 billion years old. Correnti revealed that so far they’ve discovered one possible candidate white dwarf with signs of planetary debris. If confirmed, the discovery would be far-reaching, proof that rocky planets could form in the universe less than a billion years after the Big Bang. If there were planets, is it therefore plausible that there could have also been life at this early time?

• Keith Cooper’s next blog post will report on the third day of the conference, covering the JWST’s observations of quasars – some of the brightest objects in the universe – as well as numerous exoplanetary updates.