Innholdsfortegnelse for Aug/Sep 2016 i Australian Sky & Telescope

There can’t have been too many scientific facilities that have found themselves the subject of a successful motion picture, but Australia’s very own Parkes Observatory is one of the few… or perhaps the only one. Established in the 1960s, it has been a world-leader in radio astronomy for decades. Its achievements are too many to detail here, but receiving the signals from the Apollo 11 lunar landing has to be up there are the top. It has also been used to discover more than half of all the pulsars known. And as our cover story details, Parkes is intimately involved in discovering and investigating a brand new type of astronomical phenomenon, that of fast radio bursts. It was disappointing, therefore, to read reports in the mainstream media last year, and…

Forty light-years away, a star just one-tenth the size of the Sun holds three Earth-size planets in orbit, where none was expected. Although the worlds probably aren’t habitable, their proximity to Earth makes them excellent targets for attempts to observe any atmosphere they might have. The star is an M8 red dwarf, containing only 8% of the Sun’s mass and emitting only 5% of its luminosity. It’s what’s known as an ultracool dwarf, a class of objects with effective temperatures less than half that of the Sun. (Technically, the term also includes brown dwarfs.) Some scientists suspected that such small stars might not host planets. Smaller stars should form with smaller planet-forming disks around them, and ultracool dwarfs might have such small disks that they wouldn’t be able to form…

The Astronomical Society of NSW’s annual Astro Imaging Competition is conducted every year in conjunction with the Society’s popular South Pacific Star Party (see asnsw.com for details). Australian Sky & Telescope is proud to be a supporter of the Star Party, and proud also to publish the winning photos in the deep sky and open categories for 2016. Many of these photos were taken under the ultra-dark skies of the Society’s rural property, Wiruna. Congratulations to all the winning and placing photographers! Photographer: Michael Sidonio Category: Deep sky Competition placing: First Subject: Galaxy NGC 5128 Details: Orion Optics UK AG12 telescope, Starlightxpress SXVF-H694 camera, FLI Atlas Focuser, LRGB filters, total 335 minutes exposure Photographer: Bruce Graham Category: Deep sky Competition placing: Second Subject: IC 2118 (Witches Head) Details: William Optics…

Are there particular celestial objects that have bedeviled you time and again? For a long time, Alpha (a) Vulpeculae was a thorn in my side. Along with 8 Vulpeculae, Alpha forms a wide ‘optical’ double star — not a true binary system, just two unrelated stars coincidentally aligned as seen from Earth. At 485 light-years from Earth, 8 Vul is much farther off than Alpha, which lies about 297 light-years away. To my eyes, the two stars have always shown a strong colour contrast, with Alpha a vivid orange and 8 Vul a soft blue. Of course, if one’s looking for an orange and blue double star in this part of the sky, the go-to favourite is Albireo in the neighbouring constellation Cygnus. And that was my problem — in…

August this year is a good time to see Mercury, as the planet reaches its greatest elongation (angle from the Sun) on the 17th, with the plane of the ecliptic standing almost straight up in the sky. Watch for the thin crescent Moon nearby on August 5, and Venus and Jupiter close by on the 21st to the 24th. September will see Mercury lost in the Sun’s glare as it moves toward inferior conjunction (between us and the Sun) on the 13th, before reappearing very low in the eastern morning sky by the end of the month. Venus is now the evening star, shining at magnitude –3.8 in the west after twilight. The planet will form up with the thin crescent Moon and the star Regulus on the 4th. But…

“CCD cameras observations recorded just over one degree of plasma tail.” August opens with two fading comets in the western evening sky, both of which should be visually accessible to those with backyard telescopes. The brighter of the two, C/2013 X1 (PANSTARRS) will be in Centaurus as August begins, crossing into neighbouring Hydra around the middle of the month as it slowly moves away from both Earth and Sun, all the while continuing to fade. This comet had a rather sudden surge in brightness at the beginning of the year and remained unexpectedly bright as it disappeared into the summer evening twilight. At the time of writing, little more has been reported due to the comet’s continuing proximity to the Sun, but what there has, has been rather encouraging. CCD…

There is a certain attraction in these far-away glimpses of starry swarms, for they give us some perception of the awful profundity of space. When the mind is rightly attuned for these revelations of the telescope, there are no words that can express its impressions of the overwhelming perspective of the universe. — Garret P. Serviss, Pleasures of the Telescope, 1901 Serviss penned these words of awe above in his discussion of the globular clusters that grace our sky at this time of the year. Among them he included four clusters arrayed in the shape of a backward L in the far southern reaches of Ophiuchus. The quartet’s brightest cluster is Messier 19, the only one to unveil stars through the scopes piloted by Serviss. M19 is quite simple to…

In our previous article (AS&T July 2016), we looked at 20 of the best open and globular stars clusters of the southern skies. But which are the ‘best’ nebulae and planetary nebulae? The objects described below are some of the finest to be seen south of declination –20. While none are Messier objects, all are rewarding to observe. Ten best nebulae The following 10 nebulae were discovered over a span of 153 years by seven people in the following date order: Nicolas Louis de Lacaille found 2 in 1751, William Herschel (1 in 1784), James Dunlop (2 in 1826), John Herschel (2 in 1834), Julius Schmidt (1 in 1861), Edward Emerson Barnard (1 in 1895) and Royal Frost (1 in 1904). They are all emission nebulae, with the exception of…

Every amateur astronomer needs a red torch. Red light is much less damaging to your night vision than white light (discussed last issue, page 36). Besides, that red glow looks really impressive to casual observers who might stop by to see what you’re doing. It’s easy enough to make a red torch. The trouble is that it’s diffcult to make one the perfect brightness. Worse, the perfect brightness differs depending on what you’re doing. If you’re reading a star chart before hunting for faint galaxies, you want as little light as possible, but if you’re looking for a dropped eyepiece you want enough light to glint off the barrel. The solution is a variable-intensity red torch. Put some resistance between the batteries and the bulb and you can cut down…

Of the four dwarf planets now recognised in the outer Solar System, Pluto, Eris and Haumea all have at least one moon. The fourth, Makemake, seemed to be the ‘odd dwarf out’. Astronomers used the Hubble Space Telescope to search for companions in 2006 but turned up nothing. Now they’ve turned up ‘something’. Images taken in April 2015 show an object travelling together with Makemake, which is currently some 52.4 astronomical units (7.8 billion kilometres) from the Sun. It’s 1,300 times fainter than Makemake itself. And that’s about all that Alex Parker (Southwest Research Institute) and his three co-discoverers know about this thing, whose offcial designation is S/2015 (136472) 1 — but which they nicknamed ‘MK2’ when announcing its existence. The problem is that the object shows clearly in Hubble…

Astronomers have discovered a ‘feeble giant’: one of the largest dwarf galaxies ever seen near the Milky Way. The standard model of cosmology, which suggests that dark energy and dark matter govern the universe’s evolution, predicts many more small galaxies near the Milky Way than we’ve spotted so far. Dwarfs should be the building blocks of larger galaxies like our own, so the lack has puzzled astronomers — are they not there, or are we just not seeing them? With the advent of large surveys such as the Sloan Digital Sky Survey and the Dark Energy Survey, observers have begun to identify hard-to-find dwarf galaxies. They’ve spotted dozens over the last 15 years. But theory suggests perhaps even hundreds more are yet to be discovered. Now, to the list of…

The Russian billionaire Yuri Milner, who last summer committed US$100 million to boost SETI searches to a new level, announced on April 12 a second, far more ambitious US$100 million project. Breakthrough Starshot will conduct research and development toward accelerating gram-scale interstellar probes to 20% of the speed of light, using lightsail technology and a 100-gigawatt laser array on Earth. The laser array would boost the probe out of Earth orbit by aiming at the probe’s super-reflective lightsail and, with radiation pressure, accelerating it to one-fifth the speed of light in the two minutes the mini-craft is within laser range. It will have to do this without vaporising the sail or probe. The lasers would then take a day to recharge their batteries (from a dedicated power plant), before sending…

On the night of August 24, 2001, a powerful blast of radio waves washed over Earth. By chance, the 64-metre radio dish at Parkes Observatory in New South Wales happened to be pointed in the right direction and scooped up the signal. Although the burst appeared more than 100 times brighter than ambient noise — at levels that saturated the observing system — it vanished after just 5 milliseconds. Astronomers didn’t even notice the all-too-brief event. That is, until years later. In 2006 David Narkevic (then an undergraduate at West Virginia University) was wading through 480 hours’ worth of archived Parkes data when he stumbled upon the brilliant pulse. And it wasn’t just bright. It was also smeared over a wide range of radio frequencies, with lower-frequency waves noticeably delayed,…

Rich galaxy clusters vary significantly in the distribution of galaxy types, the degree of central concentration, and whether there is a single dominant member. In some clusters a central ultra-luminous elliptical (cD-type) holds court over a contingent of lenticular (S0) and E-type galaxies. The Hercules Galaxy Cluster (Abell 2151), on the other hand, is irregular in structure, has no leading member, and abounds with star-forming spirals (roughly 50% of the population). This galactic assemblage includes a wild assortment of edge-on and face-on spirals, merging pairs and distorted interacting systems. Abell 2151 is also one of the most distant clusters that can be explored in depth with a 30-cm scope (a few of the brightest members may be visible through a 20-cm), though you’ll need dark skies, a detailed chart and…

August and September are relatively quiet months for Southern Hemisphere meteor showers. Our northern friends are just about to encounter the peak of the Perseids shower, but, unfortunately, it isn’t very visible from our part of the world. One shower that is worth seeking out at this time of the year, however, is the Southern Taurids. Known for its activity a few weeks either side of the peak, this year it is expected to be active from September 10 to November 20, reaching maximum on the morning of October 10. You should be able to see around 7 meteors per hour during the peak, but more like 2 per hour a few weeks either side. The best time to spot them is from around 2:00am until dawn. This shower is…

Look past the light curve of any variable star and you’ll see the efforts of many people. Behind this issue’s target star, S Pavonis, are 211 people who have contributed 11,950 measures across a span of 120 years. The first brightness estimate, 8.4 mag on April 21, 1895, was made by Alexander Roberts (1857-1938), a Scottish school teacher who emigrated to South Africa in 1883. On arrival his interest in astronomy connected him with one David Gill — it was Gill and Jacobus Kapteyn who produced the famous Cape Photographic Durchmusterung catalogue — and it seems it was he who encouraged Roberts to become an observer of variable stars (among other things)… something Roberts did for 20 years. S Pav is a semi-regular variable star, a late-type giant with a…

One of the Moon’s best-known telescopic treats is the 115-kilometre-long Straight Wall. This striking feature, traditionally called the Railway by British observers, is now offcially known as Rupes Recta. It casts a black shadow on the surrounding plain along the eastern shore of Mare Nubium around lunar sunrise, and it creates a distinct ribbon of brightness there at sunset. This long, straight fault is such a focus of attention that observers often don’t look closely at what else lies nearby. So I invite you to take a broader sweep of the area, especially when the terminator is just to the west near the 15-km-wide crater Nicollet. With such low lighting, the first thing to notice is that the fault cuts the middle of a big ‘half crater,’ informally named Ancient…

One of the most energetic neutrinos detected by the IceCube Neutrino Observatory might have come from a blazar. The neutrino, dubbed Big Bird, had roughly 100 times more than protons zipping around CERN’s Large Hadron Collider. One possible source for energetic cosmic neutrinos is blazars, but a previous attempt to pair two other IceCube blips with blazar flares was inconclusive. Matthias Kadler (Würzburg University) and colleagues tried again and found that the blazar PKS B1424-418 had an outburst around the same time as Big Bird arrived in IceCube. But blazars are notorious flickerers, and with a 5% chance of coincidence, the result is only a hint.…

On August 16, 2006, the veteran space probe Voyager 1 turned 100. Not in terms of years; having been launched in September 1977, it was not yet 30 years old. The achievement was in terms of distance. The spacecraft had reached a point 100 astronomical units (a.u.) from the Earth. Since one a.u. is the average distance from the Earth to the Sun (around 150 million kilometres), Voyager 1 was then 15 billion kilometres from home. Though far away, Voyager 1 was still in contact with its handlers on Earth. Signals from its tiny radio transmitter took nearly 12 hours to span the distance. A decade later it is still in touch, though its depth in space has increased to 135 a.u. In 2006, with its early triumphant flybys of…

GRAB-N-GO TO iOptron introduces the AZ Mount Pro, which incorporates its newest ‘level and go’ alignment setup. Simply level the mount using the built-in level indicator, turn on the power, and the AZ Mount Pro does the rest. The mount can be controlled using iOptron’s popular Go2Nova hand controller, with a robust database of more than 212,000 objects, and it also includes built-in Wi-Fi, enabling you to connect to your smart device running ASCOM-compliant planetarium apps. The AZ Mount Pro comes with a stainless steel tripod with 3-point leveling adjustments. It can support a scope of up to 15 kg plus the included 4.5-kg counterweight, and its 15-cm dual-dovetail saddle accepts any Vixen- or Losmandy-style dovetail mounting plate. IOPTRON | ioptron.com and dealers ALIGNMENT AID QHYCCD rolls out the PoleMaster, an…

And now the sun had set, and all the colours of the world and heaven had held a festival with him, and slipped one by one away before the imminent approach of night . . . the fireflies in the deeps of the forest were going up and down, and the great stars came gleaming out to look on the face of Yann. . . . And so Yann bore us magnificently onwards, for he was elate with molten snow that the Poltiades had brought him from the Hills of Hap, and the Marn and Migris were swollen full with floods; and he bore us in his might past Kyph and Pir, and we saw the lights of Goolunza.” — Lord Dunsany, “Idle Days on the Yann,” 1912 This month,…

A few years ago we visited Ara, the Altar, and the doubles discussed then were from the northern part of the constellation. This month’s list is from southern Ara. First up is HJ 4866 (R Arae), making a westward-pointing triangle with 3rd magnitude Zeta (z) and Eta (h) Arae. Discovered by John Herschel in 1835, it’s a fine, moderately close off-white pair in a field with some fairly bright stars, and a red star 4’ north. The primary is an Algol-type eclipsing binary. An attractive pair, 8 cm will show it well. Nearly 5 degrees preceding Alpha Arae are two little pairs within a modest field. The brighter of the two is COO 206, 7th- and 8th-magnitude stars 8” apart. This yellowish pair has two, fainter, wide companions, 58” southeast…

When Nova Ophiuchi 1998 erupted to 10th magnitude in June of that year, no record existed of any previous outburst at its location. But its behaviour and spectrum hinted that it might be a recurrent nova — so Ashley Pagnotta, Bradley Schaefer and others searched its location on the century-spanning collections of sky patrol plates at Harvard College Observatory and Sonneberg Observatory in Germany. They found that indeed, the star had erupted previously — in June 1900. They then analysed the ‘discovery effciency’ for its eruptions, based on the sky patrol plate coverage. They wrote, “We deduce a recurrence time for V2487 Oph [as it’s now known] of approximately 18 years, which implies that the next eruption is expected around 2016.” This prediction is a long shot, but diligent amateurs…

Unfortunately George Willis Ritchey didn’t live to see it happen, but the optical design he co-developed in the early 1900s proved to be profoundly important to professional and amateur astronomers during the latter half of the 20th century. Clearly gifted, albeit eccentric, Ritchey helped usher in the age of astrophysics, working with George Ellery Hale at Yerkes and Mount Wilson observatories. Following his success building Mount Wilson’s 60-inch reflector, Ritchey used it to take the finest deep-sky photographs of the day. But he was well aware that coma — the optical aberration that turns stars into seagull-shaped flares away from the centre of the field — limited what could be sharply photographed with traditional Newtonian and Cassegrain reflectors. Around 1910, Ritchey pooled his practical knowledge of telescope optics with the…

PECULIAR GALXY Beau Kreis NGC 5128 is one of the most popular targets for astrophotographers, and in this case one of Beau’s first ever astro shots. He used a Sky-Watcher 20-cm scope, Canon 5DSR camera and 200 seconds exposure. CARINA NEBULA Christopher Harcourt Another of the most popular subjects for southern photographers, and visible to the naked eye under dark skies. Christopher used a Sky-Watcher ED100 scope, unmodded Canon 70D camera and 103 subframes at 120 seconds each (ISO 1600). OMEGA CENTAURI Terry Robison Easily the best globular star cluster in the night sky (all the best objects are in the southern skies, right?), Omega is thought to comprise 10 million stars. Terry used a 25-cm RCOS scope, SBIG STL-11000 camera and a total of 142 minutes of LRB exposure.…