Clare Kenyon
Images from NIRCam (James Webb Space Telescope’s Near Infrared Camera) have flooded news and social feeds this week, showcasing a stunning deep field of galaxies upon yet more galaxies as the telescope peers further into the universe – and back into time.
Along with the blockbuster pictures, JWST (affectionately known as ‘Webb’) is providing researchers with vast swathes of data. And several Australian research groups are already eagerly sifting through it, peering through the dust in search of new insight into enigmatic galaxies, the early universe and clues to the birth of our solar system.
Contributing to a research project known as GLASS (Grism Lens-Amplified Survey from Space), University of Melbourne postdoctoral researcher Nicha Leethochawalit is using images from Webb’s NIRCam instrument to probe deep into the early universe, looking for objects at times when the universe was still very young. The objects in these images have never been seen before, and Leethochawalit is excited at the prospect of potentially finding totally new kinds of objects, so far unknown or not understood by astrophysicists. GLASS, will also use two other instruments aboard Webb, NIRISS (Near-Infrared Imager and Slitless Spectrograph) and NIRSpec (Near Infrared Spectrograph) to investigate extremely distant galaxy clusters.
NIRSpec is a particularly impressive feat of engineering, able to take spectra (which is essentially a way of looking at the amount of different energies of light) of a huge number of targets at once through the use of microshutters. As Nora Lutzgendorf, NIRSpec Instrument Scientist at ESA/STSci explains, NIRSpec consists of “a quarter of a million teeny little doors that we can individually open and close within a 3×3 arcminute field of view”. (The full Moon’s diameter is about 31 arcminutes on the sky). Typically, telescopes have only one opening with which they view a target. In comparison, each one of these microshutters on Webb could potentially be looking at an individual astronomical object – so that’s a lot of individual things to see all at once.
As part of a number of research projects led by Professor Karl Glazebrook at Swinburne University, Melbourne, postdoctoral researcher Themiya Nanayakkara is using data from these microshutters on NIRSpec to study large, dead galaxies at a time when the universe was between approximately 1.5 and 2 billion years old. These galaxies are considered ‘dead’ because star formation has effectively ceased, and researchers are keen to understand more about their evolution and their dynamics, wanting to understand how the galaxies got to this ‘dead’ point, if they can or will ever come back to life and also how interactions with other galaxies might affect them? Using the microshutters on NIRSpec, Nanayakkara hopes to see 80–100 galaxies in each NIRSpec dataset in astonishingly rich detail.
Although Webb’s ability to probe detail through the dust that normally obscures distant galaxies is a key part of Nanayakkara’s research, he also wants to understand and characterise that dust. Many of the normal processes that create dust in the universe, such as supernovae and Asymptotic Giant Branch stars (which throw off lots of material as they fuse helium in their cores), haven’t really had enough time to evolve to produce the large amounts of dust that we are seeing in the earliest times of the universe.
As Nanayakkara quips: “Dust is basically, us right? So, we want to know what’s made this dust and what happens to it over time.”
In another project, University of Queensland extrasolar planets expert Benjamin Pope is investigating the formation and evolution of protoplanetary disks around several stars in the Milky Way using the NIRISS instrument. These dusty disks of debris are thought to be the birthing grounds of planets, which coalesce and grow under the influence of gravity.
Using a custom-built “aperture masking instrument” – the brainchild of Professor Peter Tuthill from the University of Sydney (according to Pope, “the only public Australian institution contributing hardware for the JWST”) – Pope is looking at extrasolar transition disks: “where there are gaps in the disc by actively forming planets”, he explains.
This means it’s like watching the construction of a solar system from rubble light years from our own, and could provide valuable insight into the formation of our solar system.
Pope will be looking to characterise the fraction of brown dwarfs (very small stars that don’t really have enough mass to kick off nuclear fusion of hydrogen) in binary systems with other bodies. He will also investigate the enigmatic star system, Eta Corvi, where planets appear to be acting like a conveyor belt, bringing icy comets from the cold outer disk in towards the separate warmer debris disk close into the star, where they are “torn apart, making this dust in the inner solar system”. Tuthill’s aperture mask will be crucial to obtaining a very high-resolution photo of that inner system.
These observations will mark the ever first space-based detection of exo-zodiacal dust. Zodiacal light from our own solar system can be seen from a dark sky site as a glowing backdrop to the zodiac constellations (and the path of the Sun through the sky during the day) and is basically “dusty material within the inner solar system produced by long term degradation of asteroids”, says Pope.
This light, he says, could really be a “land mine for studies of direct imaging of exoplanets”, suggesting that astronomers hunting for exoplanets may not be able to see them if the background glow of the exo-Zodiacal dust is too strong.
All three groups mentioned above (along with countless other Australian collaborations) are working hard to release initial research papers within weeks, as scientists race each other to get the publicly available data analysed and published.