In the show this time, we talk to Professor Ray Norris about EMU: The Evolutionary Map of the Universe, Ian Harrison rounds up the latest news, and we find out what we can see in the December night sky from Ian Morison and Haritina Mogosanu.
In the news this month, shimmering radio bursts, the roundest object in the Universe, and life in dino-killing craters.
- Shimmering radio bursts
Another first was revealed this month in the fast-growing field of Fast Radio Bursts. The incredibly bright pulses of radio wavelength light last for a fraction of a second and almost certainly come from outside of our galaxy, which when paired with their high brightness means they must come from extremely energetic events.
Since the first description there have been seventeen so far announced (although more are definitely lurking on various astronomer's hard drives).
The new, eighteenth FRB, called 150807 after the date of its observation, announced this month is interesting for a few reasons, as detailed in a new paper by a team of scientists led by Vikram Ravi of Caltech in the USA and Ryan Shannon of the CSIRO institute in Australia.
- The roundest object in the Universe
Also in the news this month were observations of the roundest object ever seen in nature. The object is a star known as KIC 11145123. Astronomer Laurent Gizon of the Max-Planck-Institut fur Sonnensystemforschung in Gottingen Germany led a team who used the Kepler satellite to observe tiny fluctuations in the star's brightness.
KIC belongs to a class of stars known as hybrid pulsators, whose brightness subtly pulses due to wobbles in the material making up the star. Monitoring these changes in brightness over long periods of time, astronomers can spot the oscillatory patterns as different density waves propogate through the star, just as earthquakes do on Earth, an anlogy which gives the field its name of astroseismology.
By looking at nearly four years worth of Kepler data the astronomers were able to see how these different waves propogated in the star, which amongst other things depends on how round it is. KIC was found to be almost perfectly spherical, to one part in one million, with a difference of only three kilometres between its radius drawn from the centre to the poles and at the radius between the centre and the equator.
- Life in dino-killing craters
Rocks recovered from deep within the Chicxulub crater were shown this month to have properties ideal for supporting microbial life.
A group of geologists have recently been able to drill down into the Chicxulub crater for the first time, recovering from under 1.3 kilometres of sea and rock a set of cylindrical cores.
Analysing these cores showed evidence that the inner peak rings are formed from rocks dredged up from deep below the surface by the impact, and were also far less dense and more porous than expected.
Such porous rocks are excellent at hosting microbial life, and the scientists suggest that they may have provided an excellent shelter for life during the early periods of its blossoming on Earth, when our planet was subject to regular large impacts which would otherwise have created a very harsh environment.
Interview with Professor Ray Norris
Professor Raymond Norris from CSIRO Astronomy and Space Science and the Western Sydney University speaks to Minnie Mao about EMU, the Evolutionary Map of the Universe. EMU is one of the key projects for the Australian SKA Pathfinder (ASKAP). EMU will detect around 70 million radio galaxies, which is ~67.5 million more radio galaxies than we have seen thus far.
The Night Sky
Ian Morison tells us what we can see in the northern hemisphere night sky during December 2016.
- Venus below a thin crescent Moon
After sunset on December 3rd, looking low towards the south-southwest, Venus shining at magnitude -4.2, will be seen, if clear, below a very thin crescent Moon.
- December 4th after sunset: Venus, Mars and a crescent Moon
If clear after sunset on the 4th, looking low towards the south-southwest it should be possible to see a thin crescent Moon to the upper left of Mars with Venus well down to its right.
- December 13 before dawn: The Moon Occults Aldebaran in the Hyades Cluster
During the night of the 12th/13th December, the Full Moon will pass throught the Hyades Cluster and occult many of its stars. At around 6:15 UT on the 13th, it will occult -0.7 magnitude Aldabaran which lies between us and the cluster. This may be a grazing occultation from parts of the UK.
- December 14th and 15th after midnight: the Geminid Meteor Shower
The early mornings of December 14th and 15th will give us the chance, if clear, of observing the peak of the Geminid meteor shower. Sadly, this is not a good a year as these nights are just after the Full Moon and the fainter meteors will not be seen. However, as I saw last year, the Geminids can often produce near-fireballs and so the shower is still well worth observing. An observing location well away from towns or cities will pay dividends. The relatively slow moving meteors arise from debris released from the asteroid 3200 Phaethon. This is unusual, as most meteor showers come from comets. The radiant - where the meteors appear to come from - is close to the bright star Castor in the constellation Gemini as shown on the chart. If it is clear it will be cold - so wrap up well, wear a woolly hat and have some hot drinks with you.
- December 22nd/23rd - late evenings: the Ursid Meteor Shower
The late evenings of the 22nd and 23rd of December are when the Ursid meteor shower will be at its best - though the peak rate of ~10-15 meteors per hour is not that great. Pleasingly, the Moon will not affect our view during much of the night. The radiant lies close to the star Kochab in Ursa Minor (hence their name), so look northwards at a high elevation. Occasionally, there can be a far higher rate so its worth having a look should it be clear.
- December 30th/ 31st after sunset: Venus closes on Mars
After sunset at the end of the month, Mars, in Aquarius will be seen to the upper right of Venus low in the south-southwest.
- December 6th and 20th: The Alpine Valley
These are good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb is the Appenine mountain chain that marks the edge of Mare Imbrium.Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image a thin rill runs along its length which is quite a challenge to observe.Over the next two nights following the 6th the dark crater Plato and the young crater Copernicus will come into view. This is a very interesting region of the Moon!
Haritina Mogosanu from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during December 2016.
- We'll start our tour in Orion, sitting high in the east after dark. Orion lies along the celestial equator, and can be seen (at least partially) throughout the world. As he was invented in the Northern hemisphere, in New Zealand we see him upside down. Orion contains a number of interesting objects to observe with both binoculars or telescopes. If you look carefully you may see the middle star of Orion's sword has a fuzzy appearance. This is the Orion Nebula, which is a stellar nursery, a huge cloud of gas and dust in which new stars are being born. In the heart of the Orion nebula is a small group of bright stars known as the Trapezium Cluster. The ultraviolet radiation from these stars is lighting up the surrounding gas.
- Following Orion's belt to the left we come to an upturned V shape of stars marking the head of Taurus the bull. At the bottom of this V is the bright orange star Aldebaran, at around 65ly away, representing the eye of the bull. The other stars in the V are part of the more distant Hyades cluster. At 153 ly away, the Hyades is the closest, and one of the best studied, open clusters to Earth. It is estimated to be around 625 million years old. Over time the cluster will continue to spread out and disperse into space, with some of the largest and brightest members already coming towards the ends of their lives.
- Following Orion's belt to the right, you can follow the band of the Milky Way around the sky, through the False and Diamond Crosses to Crux, the Southern Cross, low in the south. Sat beside the Southern Cross is a dark patch called the Coal Sack Nebula. Known as a dark nebula, the gas and dust in this cloud is blocking the light from more distant stars, obscuring them from our view. To Maori the Coal Sack Nebula is known as Te Patiki, or the Flounder.
- In our western skies, we see a trio of planets this month. Mercury is low on the southwestern horizon for the first half of the month, setting around an hour and a half after the sun, before sinking into the evening twilight after the 15th. Venus is higher in the west, the first thing you'll see as the sky begins to darken, and sets close to midnight. Mars is much fainter and to the top right of Venus, moving through Capricorn and into Aquarius over the course of the month
- The Phoenicids reach their peak on 6th December and are thought to be associated with the comet D/1819 W1 (Blanpain). With the radiant in the constellation of Phoenix, not far from Achernar, this shower is well placed for southern hemisphere observers throughout the hours of darkness. The minor Puppid-Velids meteor shower also reaches its peak at around the same time with a zenithal hourly rate of around 10.
- The Geminids are peaking on the 15th of the month. This is one of the best meteor showers of the year, but we are not well placed for viewing in New Zealand, with the radiant in the constellation of Gemini and well north of the equator. The constellation is at its highest around 3 am, but still appears low in our northern sky. Due to this low height we only see around half of the meteors visible to those in the northern hemisphere.
Odds and Ends
- A large unidentified object fell from the sky into a mountainous region in Myanmar - destroying a jade miner's tent but fortunately injuring nobody. What is it? Where did it come from? What are the odds of being hit by space debris? Read more here.
- Development in Africa with Radio Astronomy (DARA Project). The SKA is a truly transformational project with the aim build up to 3000 dishes that extends current capabilities in radio astronomy by orders of magnitude. So, although the core of the SKA telescope will be in South Africa, the outlying stations will be located in 8 partner countries across Africa, namely: Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, and Zambia. Given that there is virtually no astronomy activity in the partner countries before and at present, the DARA Project is integral to bring the other African countries up to speed with the SKA project.
- A new possible supercluster, the Vela supercluster, has been discovered in the southern zone of avoidance (ZOA) along the galactic plane in the Vela constellation. A supercluster in this position was proposed as early as 2008 in order to try to resolve discrepancies in the measured peculiar velocity of the Local Group and the velocity calculated from the influence of the Shapley supercluster 650 million light years away. New spectroscopic data from the Southern African Large Telescope and Anglo-Australian Telescope combined with peculiar velocity analysis by 6dFGS and 2MTF seem to confirm a large extended mass in the direction of the Vela constellation which extends to either side of the galactic plane with the bulk of the mass unobservable in the ZOA. Follow-up observations are set to be done in 2017 with Taipan and the South African SKA Pathfinder MeerKAT in order to confirm the Vela supercluster and to try to uncover new cosmology.
|Interview:||Professor Ray Norris and Minnie Mao|
|Night sky:||Ian Morison and Haritina Mogosanu|
|Presenters:||Fiona Healy, Naomi Asabre Frimpong and Francesca Pearce|
|Editors:||Naomi Asabre Frimpong, Benjamin Shaw, Claire Bretherton, Ian Evans, Xiaojin Liu and Charlie Walker|
|Segment Voice:||Iain McDonald|
|Website:||Monique Henson and Stuart Lowe|
|Cover art:||The Parkes Radio Telescope CREDIT: CSIRO|