Innholdsfortegnelse for March - April 2022 i Australian Sky & Telescope

PLANETS ABOUND in the Milky Way. They probably do in other galaxies, too, but the usual techniques can’t reach far enough to tell. Using an innovative method, Rosanne Di Stefano (Center for Astrophysics, Harvard & Smithsonian) and colleagues announced a possible extragalactic exoplanet in the journal Nature Astronomy. In X-ray binaries, a black hole or neutron star siphons material off a companion star. Infalling material heats up until it emits X-rays. This hot inner region is small enough that a planet passing in front of it could block most or all of the radiation. Di Stefano and collaborators set out looking for such a signal, examining observations of 238 X-ray binaries in three nearby spiral galaxies: M51, M101 and M104 (the Whirlpool, Pinwheel, and Sombrero galaxies). The hunt struck gold…

THE SIGNAL was the closest we’ve come to thinking we had found intelligent alien life. Discovered as part of a 10-year initiative to find technosignature in nearby star systems, Breakthrough Listen Candidate 1 (or BLC1) appeared to come from Proxima Centauri, the nearest star to the Sun. But in a pair of articles published in the journal Nature Astronomy, team members concluded that the signal is of human origin. BLC1 is the only signal to date that ticked the most important boxes for alien origin. It was narrowband — a tone purer than any natural process could produce — and no known electronics on Earth intentionally transmit at that frequency. It also persisted over several hours. What really made BLC1 exciting, though, was that its frequency changed, drifting exactly as…

JUST OVER TWO WEEKS after launch, the origami-like James Webb Space Telescope (JWST) unfolded just as expected. On January 8, NASA controllers announced that the telescope’s final primary mirror segment had locked into place, marking the end of the deployment phase. “Today, NASA achieved another engineering milestone decades in the making,” said Bill Nelson, NASA Administrator. “While the journey is not complete, I join the Webb team in breathing a little easier and imagining the future breakthroughs bound to inspire the world.” JWST launched on an Ariane 5 rocket from the Guiana Space Centre on December 25, 2021. The following couple of weeks saw the telescope’s separation from the launch vehicle’s second stage, the unfolding and tensioning of its sunshield, and myriad other steps to full deployment. The observatory sports…

Another mission is on its way to an asteroid: the Double Asteroid Redirect Test (DART). Launched on November 24, 2021, it’s not a science mission but an engineering one: Its goal is to change an asteroid’s orbit by slamming something heavy into it. The ultimate question the mission will help us answer is, Can humans prevent a calamitous asteroid impact on our home planet? Before you panic, DART isn’t going to change a near-Earth asteroid’s orbit around the Sun. Its target is smaller. DART aims at a collision with Dimorphos, the small moon of the near-Earth asteroid 65803 Didymos, in late 2022. A small Italian-built satellite, LICIACube, will separate from DART to watch the impact unfold, sending pictures home to Earth. Meanwhile, ground-based optical and radar measurements will enable us…

WE HUMANS LOVE to categorise things. Prior to the detection of planets beyond our Solar System, this was straightforward. The big ball of fusing hydrogen in the centre of the Solar System? A star, our Sun. The distant, giant, hydrogen-rich planets in the outer Solar System? Gas planets. The little spheres of rock like the one we call home? Terrestrial planets. But as new objects are found, our neat categories become more and more messy. Much like the discovery of the Kuiper Belt led to the demotion of Pluto to its dwarf-planet status, as we find more objects outside the Solar System, we realise that many are not easily divided into the bins we initially chose. Since the 1990s, astronomers have discovered thousands of objects that are neither stars nor…

I recently gave a talk for an astronomy club, describing the work I do here in the pages of AS&T, and more specifically on how visual variable star estimates and photometric measures complement each other rather than compete. Unfortunately, I seemed to have failed, since the flavour of question-time was, “Given the accuracy of photometric measures, why do visual observers bother?” In response, I gave the following as an example. Visual observers closely monitored the recurrent nova T Pyxis in quiescence and were able to quickly notify the wider astronomical community of its 2011 outburst. The resulting light curve shows (mostly) visual measures in quiescence and through the early rise in brightness, with CCD observers taking over and capturing the light curve in greater detail. So visual and CCD observers…

EVER SINCE DIGITAL DETECTORS supplanted film as the dominant photographic medium, some of the most colourful and appealing images of deep sky targets have come from talented amateurs armed with sensitive electronic cameras and high-quality telescopes. Yet many of us with relatively modest equipment look at the pictures produced with giant telescopes at professional observatories and dream about taking pictures as good. You might think, “If only I had a bigger telescope or more sensitive camera…” Well, the good news is that with a bit of patience and persistence, you can capture deep sky photographs that rival or even exceed the depth of those recorded by the pros and reveal rarely seen features. In early 2013 I set out to realise a long-time dream of mine: to take an exceedingly…

What is possibly Australia’s longest continually running astro-gathering, the South Pacific Star Party (run by the Astronomical Society of NSW) has been pencilled in for May 26 to 29. The SPSP is held at the Society’s dark sky site near Ilford, between Lithgow and Mudgee and about three hours’ drive north-west of Sydney. Keep an eye on the event website (asnsw.com/spsp) for details as they come to hand. Another long-running event is the Queensland Astrofest. As with the SPSP, last year’s event had to be cancelled, but organisers are hopeful that it will go ahead this year. The planned dates are July 22 to 31. Announcements will be published on the event website (qldastrofest.org.au). A further astrofest, the Perth Astrofest, is due to be held in October or November. Normally…

ASTRONOMERS HAVE precisely mapped out 12 stellar streams in and around the Milky Way. These ribbon-like structures of stars moving in a coherent fashion are the remains of satellite galaxies or globular clusters ripped apart by our galaxy’s tidal forces. Tracking their 3D positions and motions will eventually help to chart the distribution of dark matter in the Milky Way. Stellar streams were discovered in the 1970s, but the number of known systems has increased spectacularly over the past years, thanks to programs such as the Pan-STARRS 1 Survey on Haleakala, Hawai‘i, and the Dark Energy Survey in the Chilean Andes. At present, astronomers know of almost 70 streams. A team led by Ting Li (University of Toronto) used a fibre-optics spectrograph on the 3.9-metre Anglo-Australian Telescope in NSW to…

WHEN ASTRONOMERS STARTED scouring space for signs of planets around other stars, they thought they’d be looking in the mirror. Everyone expected to see ourselves reflected back at us — after all, there’s supposed to be nothing special about us or our place in the cosmos. It should have been a tick-box exercise to find copy after copy of home. Yet the more worlds we found, the more we realised that, when it comes to exoplanets, the universe is more like a deceptive hall of mirrors — it’s hard to distinguish between truth and illusion. We’ve found entire classes of planets that simply don’t exist in our own backyard. Hot Jupiters that buzz around their stars in days, worlds where iron rain whips about on ferocious winds. Yet perhaps the…

From earliest times astronomers were aware that among the fixed stars there were a few, equally fixed but un-star-like objects which appeared to them as ‘misty patches’ or ‘little clouds’. These were the nebulae and their unique appearance and comparative rarity exercised the imagination of all who enquired into the nature of the universe. Kenneth Glyn Jones, The Search for the Nebulae (1975) WE 21ST-CENTURY AMATEUR astronomers are fortunate to have wonderfully detailed and accurate printed and computer-generated star charts to aid us in our explorations of the heavens. When I started observing in 1984, I was thrilled with Wil Tirion’s Sky Atlas 2000.0, published in 1981. Although I didn’t know it at the time, Tirion’s atlas was modelled on Antonín Becÿváÿ’s Atlas of the Heavens: Atlas Coeli 1950.0 (the…

To lovers of mythology, Gemini brings to mind Castor and Pollux, the mighty twin brothers of ancient Greek legends. But to lovers of the night sky, Gemini means Pollux and Castor — a pair of bright stars shining only 4½° apart. However, there’s a lot more to see in Gemini than its famed pair of luminaries. Telescope users know the constellation for deep sky treasures such as the bright open cluster M35, but the attractions I mainly want to focus on are those visible to the naked eye. Pollux and Castor mark the imagined heads of the mythological twin brothers they’re named for. Two nearly parallel lines of moderately bright stars run in a southwesterly direction from Pollux and Castor, outlining the bodies of the Twins and pointing toward Orion…

Until recently, scientists since Galileo’s time who studied the Moon were astronomers, not geologists. It wasn’t until the late 1950s and early 1960s that Eugene Shoemaker and Robert Hackman of the U.S. Geological Survey (USGS) developed lunar stratigraphic knowledge based on telescopic and photographic studies of the spatial relations among lunar landforms. They chose the southeast quadrant of Mare Imbrium to determine sequences of events by mapping the overlap of deposits created by each event. The most recent Imbrium episode that Shoemaker and Hackman recognised was the formation of the crater Copernicus, whose radiating bright rays and secondary craters adorn nearby Mare Imbrium, Montes Apenninus (Apennine mountains), and more distant terrains. Copernicus’ formation must be the youngest major event in this area of the Moon, they concluded. The fact that…

Castor and Pollux, the sibling soldiers of classical mythology, stand side by side to create Gemini, a constellation that rewards repeated telescopic exploration. I’m drawn to the eastern side of the constellation in search of NGC 2392, popularly known as the Clown Face Nebula. NGC 2392 is a planetary nebula. The term was coined by 18th-century observers who commented on the vaguely planetlike appearance of such objects when seen through telescopes. However, a planetary nebula has nothing to do with planets. It is formed when an aging red giant star becomes unstable and sloughs off its outer layers to create expanding shells of gas. As the ejected material balloons into space, a hot white dwarf — the remnant core of the original star — energises the shed shells into luminescence.…

In 2015 a group of amateur astronomers and science enthusiasts, coordinated by Garry Copper, Leigh Tschirpig and Phil Betts, met and decided to form an astronomy group in Tamworth in northern NSW. At the time, Garry commented he had been waiting 30 years for this to happen! The group was soon joined by Stuart Goff, Lindsay Lowe, Michael McHugh, Barry Gilbert, Matt Dodds, Raymond McLaren, Ray Hare, Warwick and Margie Schofield and others. The Tamworth Regional Astronomy Club (TRAC) became an incorporated organisation in early 2016 and, as the membership quickly grew, so did the Club’s extraordinary collection of assets. Within a matter of months, the group received an amazing donation of the award-winning ‘Jos Roberts Telescope’. With its high-quality, 91-cm primary mirror produced by Intermountain Optics in the USA,…

IN RECENT YEARS, the popularity of Solar System photography has grown by leaps and bounds. Maybe it’s due to people being stuck at home during the long COVID-19 pandemic, but fantastically detailed closeups of Jupiter, Mars and Saturn (not to mention the Sun and Moon) appear in our inboxes with much greater frequency than in past years. This surge in popularity is being met by new companies getting into the business. One of those is Player One Astronomy, a Chinese manufacturer that recently announced a line of high-speed video cameras geared specifically toward those with an interest in taking pictures of the large bodies in our Solar System. We borrowed both a monochrome and a colour camera to see how they perform. Elegant package Player One Astronomy’s planetary and solar…

Perth-based Roger Groom is a software engineer by day and an astrophotographer by night. Developing his skills over the past 20 years, he conducts astrophotography workshops (www.astrophotography.com.au) and operates a remote telescope dark sky hosting site (www.astroobservatorieswa.com.au). He also participates in astronomical research and has previously been Chairperson of the Perth Observatory Volunteer Group. What got you into astronomy? I’ve always interested in space but there are a few distinct moments that stick in my memory. In the 1990s my uncle built his own 20-cm Newtonian (including the mount) and subsequently purchased a 20-cm SCT. He would bring them out to the dark skies of my parent’s property, and I would join him. The same uncle also travelled to Houston for work and brought back poster books of the NASA…

When we try to set out the history of astronomy, we tend to emphasise two great periods of discovery, with a long dark space in between. We think of the ancient Greeks such as Hipparchus and Aristarchus, building on the work of the Babylonians and culminating in the venerated Ptolemy. A few centuries after him, Rome fell, and the barbarians took over. We pick up the trail more than a millennium later, with the Europeans Copernicus and Tycho, Kepler and Galileo, and Newton. So what happened in between, in the ‘Dark Ages’? Was no-one doing astronomy then? And was there any connection between those great eras, the Greeks and the ‘moderns’? In reality, the Dark Ages were dark only in Europe. In the Middle East, the light of knowledge and…

Teams of amateur astronomers are already contributing to the Lucy mission. Volunteers are assisting mission astronomers by providing careful observations of how long stars wink out (or don’t) as Trojans pass in front of them as seen from various locations. The stellar occultations have already yielded improved orbit ephemerides and size and shape estimates for Lucy’s targets — for instance, thanks to amateurs, we now know that slow rotator Leucus is surprisingly elongated and likely heavily cratered, while Patroclus’ binary partner Menoetius seems to have a huge impact crater that has gouged a void out of its south pole. Such information makes flyby planning simpler and more efficient. The Lucy team welcomes observers from around the world. Read more at https://is.gd/lucyoccultation.…

Our targets this month are the open clusters Collinder 132 and Collinder 140 in the southeastern corner of Canis Major, the Great Dog. Follow the Dog’s tail to its tip, Aludra, or Eta (η) Canis Majoris, and you’ll find the two clusters south and southwest of the 2.4-magnitude star. I vividly remember the first time I encountered these celestial gems. I was camping in a national park, working my way through the Milky Way. My usual route from Canis Majoris into Puppis went a little farther north, but that night I decided to head south. I stumbled into a wonderland of bright stars, clusters and asterisms that ran from the tail of the Dog, then across Puppis and into Vela, the Stern and the Sails, respectively, of the ancient constellation…

All comet observers agree that the objects of their interest are unpredictable, and this was certainly demonstrated by C/2021 A1 (Leonard) when it emerged into southern skies in December and January. Frequently, a predicted spectacle turns out to be less impressive than expected but, fortunately, this particular comet provided the opposite surprise. Instead of peaking at around magnitude 6 as we had predicted (which was actually more optimistic than some of the expectations published last October when the comet’s brightness increased stalled), C/2021 A1 exceeded third magnitude, displayed a magnificent tail visible through binoculars (and faintly even to the naked eye from suitable locations) and underwent a series of quasi-periodic brightness outbursts as it approached perihelion! The pictures on these pages and in our Gallery (page 76) show just how…

DEEP SKY CAMERA SBIG announces a new CMOS camera in its line of deep sky detectors. The SBIG STC-7 camera (US$3,495) features a 14.4 x 9.9 mm, 7.1-megapixel Sony IMX428 CMOS detector with 4.5-micron-square pixels in a 3,208 x 2,200 array. This 12-bit camera has a full well capacity of ~22,500 e- with a peak quantum efficiency of 78%. The STC-7 operates in multiple gain modes with its innovative Stack Pro automatic, in-camera stacking program to produce smooth, low-noise images with high dynamic range. Additionally, the STC-7 has a built-in, 8-position filter wheel that comes complete with a full complement of LRGB and 6.5-nanometer narrowband filters. The camera is ASCOM-compatible and connects to a computer through a single USB 3.0 interface. Each purchase includes a universal power supply, a 2-inch…

And now for something completely different. If you’re a reader of this column, perhaps you’ve noticed that thus far we’ve showcased projects for you to undertake with telescopes in your backyard. But maybe you don’t have a scope or the requisite recording equipment, or you can’t readily get to dark skies. Yet you’re yearning to contribute to scientific discovery. The good news is that for many endeavours, such as this one, you won’t need a telescope. This project doesn’t even deal with visual wavelengths! All you need is a computer with an internet connection. FRBs Radio astronomy has brought us many a wondrous thing, from revealing the origin of our cosmos to imaging supermassive black holes. Lately, scientists have been blown away by fast radio bursts, or FRBs. As their…

WE OFTEN THINK OF cosmic scales as being nearly ungraspable. Recently, on a long drive, I travelled about one millionth the distance to the Sun, which of course is only the nearest star in our galaxy, which is one of many galaxies in our local cluster of galaxies, which is one of many such clusters in the observable universe. Against such universal scales, the everyday usually doesn’t compare. But the reason for my drive was to see 190-million-year-old dinosaur footprints beside a river. Here, early cousins of Tyrannosaurus rex walked across muddy ground that, over time, solidified into rock and preserved these footprints as fossils. When I put my hand inside the much larger, three-toed footprint in the sandstone, I immediately noticed how smooth the footprints were compared to the…