Australian Sky & Telescope August/September 2023

SPECTRUM READING THE ARTICLES in this issue about Williamina Fleming and E.E. Barnard, has made me reflect on how much we owe to these and other giants of the astronomy world, now long since gone. This holds true for all aspects of astrophysics — e.g. planetary studies, solar physics — but perhaps for none more so than the pioneers of the deep sky. Without their tireless efforts, our species would have had absolutely no clue about the nature, size and scale of our cosmos and where we fit into it. Just think — it’s not much more than 100 years ago that most astronomers believed that our Milky Way galaxy was the full extent of the universe. They had no idea that there were other galaxies beyond, nor were they…

Continuing its run of ground-breaking discoveries, the James Webb Space Telescope (JWST) has snapped the clearest images yet of the dusty debris disk around Fomalhaut, a bright, young star 25 lightyears away in Piscis Austrinus. The images reach a resolution and sensitivity far beyond the capability of earlier instruments. András Gáspár (University of Arizona) and colleagues presented new details in this planet-forming disk on May 8 in Nature Astronomy. The team also included new Hubble Space Telescope images in their analysis. Previously, Hubble, the Spitzer Space Telescope and other telescopes had shown that Fomalhaut hosts a far-out ring of planet-forming debris that’s akin to the Kuiper Belt in our Solar System. Analysis of the system’s brightness at different wavelengths had also suggested the presence of a dusty inner disk analogous…

ASTRONOMERS HAVE PROVIDED the most direct evidence yet that dark matter does not consist of ultramassive particles. The work, based on supercomputer calculations, suggests that dark matter is instead made up of axions — hypothetical particles so light that they travel through space more like waves. If correct, the researchers’ conclusions would not only help reveal what 85% of matter in the universe is made of; the results could also lead to new physics beyond the standard model. The study was published April 20 in Nature Astronomy. Dark matter is tricky to investigate because it doesn’t emit, absorb or reflect light. So instead, a team led by graduate student Alfred Amruth (University of Hong Kong) looked for the material’s influence on gravitational lensing. In this effect, a galaxy and its…

Meteorite crashed into New Jersey home When Suzy Kop stepped into her father’s bedroom on May 8, she saw a black, mango-size rock on the floor, its broken surface exposing a creamy interior. Looking around, she spotted two holes in the ceiling, and she knew something wasn’t right. Some 15 minutes before Kop had arrived (around 12:30pm), there was a report of a fireball in the area. As it happened, the heavy end of that falling star crashed through the roof of the home in Hopewell Township, New Jersey. The meteorite struck the floor with such force that it rebounded and punched a second hole in the ceiling before landing back on the floor. Unsure what to do, Kop called the Hopewell police for assistance. A hazmat team arrived to…

Astronomers armed with new James Webb Space telescope (JWST) images have gotten under the high-altitude skin of the mini-Neptune dubbed GJ 1214b. The results, published in Nature, suggest that this planet’s atmosphere is composed of some combination of water, methane and hydrogen cyanide, all wrapped thickly in highly reflective clouds or haze. GJ 1214b swings around its red dwarf star every 1½ days, so it’s scorchinghot. But it maintains an atmosphere, and from the world’s lightweight density, astronomers had suspected that water in some form would be a major constituent. But multiple attempts to take the atmosphere’s spectrum as the world passed in front of its star were stymied by what appeared to be highaltitude clouds or hazes. Now, JWST observations of the full orbit have enabled a team led…

Saturn has reclaimed the record for most moons in the Solar System with the discovery of 63 new moons. All are only a few kilometres in size and have orbits far from the planet. At the time of writing, the International Astronomical Union’s Minor Planet Center (MPC) has published the moons’ orbits in a series of Minor Planet Electronic Circulars issued between May 3 and 23. The new discoveries bring Saturn’s total moon count to 146, including 24 ‘regular’ moons, which formed around the planet, and 122 smaller, ‘irregular’ moons on elongated, and tilted orbits. The new reports more than double Saturn’s irregular moons and put Saturn far ahead of Jupiter’s 95 moons (which had put Jupiter in first place earlier this year). The torrent of Saturnian discoveries comes from…