Australian Sky & Telescope April 2023

BACK IN 1994, I was given the chance of a lifetime. NASA invited me to fly as a guest aboard its Kuiper Airborne Observatory, a converted military C-141 Starlifter aircraft, modified to have a telescope pointing out through a hatch in its side. And the flight was to be a very special one, part of a campaign being flown out of Melbourne and over Bass Strait to observe the fragments of Comet Shoemaker-Levy 9 as they crashed into Jupiter. I well remember the excitement of that flight, the interior of the aircraft (very spartan; no inflight entertainment!) and the scientists at their consoles, intently watching as data streamed in from the giant planet. It was an unforgettable ride. Kuiper was retired after 21 years of operations to make way for…

NEWS NOTES THE DISTANT DWARF planet 50000 Quaoar appears to have a ring that spans far beyond where it ought to be stable. “That is not where it was supposed to be,” says Bruno Morgado (Federal University of Rio de Janeiro), lead author of a team of 59 professional and amateur astronomers who have reported the discovery. At 1,110 km in diameter, Quaoar is one of the largest objects known in the outer Solar System. Its single moon, named Weywot, spans about 160 km and was discovered in Hubble images in 2007. But the first signs of material around Quaoar didn't come until 2018; even then, evidence was insufficient to call it a ring, says Morgado. He began studying Quaoar in 2020 with the European Space Agency's CHEOPS space telescopes.…

Although mass media outlets reported on the Quaoar discovery, they failed to mention that it was Australian amateur astronomers who made the crucial first detections of a dense ring around the dwarf planet. Jonathan Bradshaw, Renato Langersek, John Broughton, Steve Kerr, Dave Gault, Peter Nosworthy, Bill Hanna and Dave Herald all acquired data during a 2021 occultation. They hoped to see the background star disappear over an extended period, but instead, Bradshaw witnessed a brief dip five minutes early that was later identified in Langersek and Broughton's lightcurves, but absent from five others. Broughton concluded at the time that the evidence ruled out an unknown moon being the cause, leaving a Neptune-like ring as the only plausible alternative.…

RESULTS FROM A COMPLEX new analysis support cosmologists' suspicions that something is missing from our understanding of the universe. For the most part, our standard theory of cosmology fits observations like a glove. With just a handful of ingredients, scientists can explain the patchy pattern of the cosmic microwave background (CMB) — the relic radiation from the universe's primordial age — and how the nearly uniform soup it came from transformed into the Swiss cheese of galaxy clusters and cosmic voids we see today. But some nagging problems remain. The most touted is the Hubble tension, a discrepancy between how fast the universe appears to be expanding today and how fast it ‘should' be expanding, based on what we see in the early universe. But there's another, more subtle discrepancy:…

ASTRONOMERS USING the James Webb Space Telescope (JWST) have confirmed the most distant galaxies ever observed. Some formed when the universe was just 2% of its current age. The results, based on detailed spectroscopic measurements, provide concrete distances to galaxies first revealed in Webb images. “It was crucial to prove that these galaxies do, indeed, inhabit the early universe,” says Emma Curtis-Lake (University of Hertfordshire, UK). “It's very possible for closer galaxies to masquerade as very distant galaxies.” Curtis-Lake is part of the JWST Advanced Deep Extragalactic Survey (JADES) group, which has been given a month's observing time spread over two years to take spectra of distant galaxies. The first part of this effort saw them observe an area of the sky in and around the famous Hubble Ultra Deep…

NEWS NOTES THE GRAVITATIONAL-WAVE signal known as GW190521 represents the collision of a roughly 90-solar-mass black hole with a 65-solar-mass one. The event has long excited astronomers, because exploding stars shouldn't create black holes with masses between roughly 50 to 120 Suns. With only about 0.1 second of data, researchers have fit a whole slew of solutions to GW190521's signal. Astronomers initially settled on describing GW190521 as the merger of a pair of big black holes orbiting each other at wonky angles, causing the plane of their nearly circular orbit to wobble around. But others have instead considered highly elongated orbits, head-on collisions, or proposed that the mass estimates are just wrong. Publishing in Nature Astronomy, Rossella Gamba (Friedrich Schiller University Jena, Germany) and colleagues threw their hats into the…