Hubble images first-ever predicted supernova explosion

The NASA/ESA Hubble Space Telescope has captured the image of the first-ever predicted supernova explosion. The reappearance of the Refsdal supernova was calculated from different models of the galaxy cluster whose immense gravity is warping the supernova’s light.

 

Many stars end their lives with a bang, but only a few of these stellar explosions have been caught in the act. When they are, spotting them successfully has been down to pure luck — until now. On 11 December 2015 astronomers not only imaged a supernova in action, but saw it when and where they had predicted it would be.

The supernova, nicknamed Refsdal, has been spotted in the galaxy cluster MACS J1149.5+2223. While the light from the cluster has taken about five billion years to reach us, the supernova itself exploded much earlier, nearly 10 billion years ago.

 

Refsdal’s story began in November 2014 when scientists spotted four separate images of the supernova in a rare arrangement known as an Einstein Cross around a galaxy within MACS J1149.5+2223 (heic1505). The cosmic optical illusion was due to the mass of a single galaxy within the cluster warping and magnifying the light from the distant stellar explosion in a process known as gravitational lensing.

 

"While studying the supernova, we realised that the galaxy in which it exploded is already known to be a galaxy that is being lensed by the cluster,” explains Steve Rodney, co-author, from the University of South Carolina. “The supernova's host galaxy appears to us in at least three distinct images caused by the warping mass of the galaxy cluster.”

 

These multiple images of the galaxy presented a rare opportunity. As the matter in the cluster — both dark and visible — is distributed unevenly, the light creating each of these images takes a different path with a different length. Therefore the images of the host galaxy of the supernova are visible at different times.

 

Using other lensed galaxies within the cluster and combining them with the discovery of the Einstein Cross event in 2014, astronomers were able to make precise predictions for the reappearance of the supernova. Their calculations also indicated that the supernova appeared once before in a third image of the host galaxy in 1998 — an event not observed by any telescope. To make these predictions they had to use some very sophisticated modelling techniques.

 

“We used seven different models of the cluster to calculate when and where the supernova was going to appear in the future. It was a huge effort from the community to gather the necessary input data using Hubble, VLT-MUSE, and Keck and to construct the lens models,” explains Tommaso Treu, lead author of the modelling comparison paper, from the University of California at Los Angeles, USA. “And remarkably all seven models predicted approximately the same time frame for when the new image of the exploding star would appear”.

 

Since the end of October 2015 Hubble has been periodically peering at MACS J1149.5+2223, hoping to observe the unique rerun of the distant explosion and prove the models correct. On 11 December Refsdal finally made its predicted, but nonetheless show stopping, reappearance.

 

“Hubble has showcased the modern scientific method at its best,” comments Patrick Kelly, lead author of the discovery and re-appearance papers and co-author of the modelling comparison paper from the University of California Berkeley, USA. “Testing predictions through observations provides powerful means of improving our understanding of the cosmos.”

 

The detection of Refsdal’s reappearance served as a unique opportunity for astronomers to test their models of how mass — especially that of mysterious dark matter — is distributed within this galaxy cluster. Astronomers are now eager to see what other surprises the ongoing Hubble Frontier Fields programme will bring to light.

Janaury | the Position and Appearance of the Moon & Planets

 

Please click on each image for a larger view

NASA’s STEREO-A Resumes Normal Operations

On Nov. 9, 2015, NASA’s Solar and Terrestrial Relations Observatory Ahead, or STEREO-A, once again began transmitting data at its full rate. For the previous year, STEREO-A was transmitting only a weak signal—or occasionally none at all—due to its position almost directly behind the sun. Subsequently, as of Nov. 17, STEREO resumed its normal science operations, which includes transmission of lower-resolution real-time data—used by scientists to monitor solar events—as well as high-definition, but delayed, images of the sun’s surface and atmosphere.

One of the key components of the real-time data, known as beacon data, is what's called coronagraph imagery – in which the bright light of the sun is blocked out in order to better see the sun's faint atmosphere. Coronagraphs are key for monitoring when the sun erupts with a coronal mass ejection, which can send a giant cloud of solar material out into space. Such space weather can lead to interference with radio communications, GPS signals and satellites.

“STEREO-A’s real-time data is key for scientists to make accurate models of interplanetary space weather,” said Yari Collado-Vega, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Having a second set of coronagraph images, in addition to those from the Solar and Heliospheric Observatory (SOHO), means we can measure coronal mass ejections much more accurately.”

For the past year, however, beacon data was only received for a few hours each day—if at all—limiting scientists’ ability to monitor the sun. Since August 2014, our line of communication to the spacecraft was so close to the sun that pointing the antenna straight at Earth also meant pointing it nearly directly at the sun, which would cause the spacecraft’s antenna to dangerously overheat. Now that STEREO-A has emerged from behind the sun, scientists have once again pointed the main lobe of STEREO-A’s antenna towards Earth and the stronger signal means that the majority of the beacon data can once again be picked up.

STEREO-A is also using this stronger signal to send high-definition views of the sun’s far side with a two- to three-day delay. These detailed images of the sun’s surface and atmosphere allow scientists to better track the formation of solar events.  

“We’re now using STEREO-A to its fullest capabilities, given how far away it is,” said Terry Kucera, deputy project scientist for the STEREO mission at Goddard.

STEREO-A’s twin spacecraft, STEREO Behind, has been out of communication since October 2014, when communications were lost following a planned reset of the spacecraft. For several months, STEREO-B’s orbit took it behind the sun from our perspective, making it impossible to send messages to the spacecraft. But STEREO-B will soon emerge from the sun’s interference zone, and spacecraft operators will resume their attempts to contact the spacecraft on Nov. 30.

December 2015 | Stars of the far South

Running time: 33m 40s

Acknowledgements: Stefano Quaresima, Trevor Barry, Oliver Czernetz, & Maria Sobrina Yu.

This month’s program marks the shows’ 2^nd Anniversary.

Our program is for a worldwide audience, and I get a lot of questions asking about what the constellations are on view as seen in the southern hemisphere, and whether the night sky looks any different from what we in the far north are used to. In this program I attempt to answer your questions by becoming a virtual tourist, and taking you to Adelaide, Australia to see the ‘Summer’ night sky.
 

Thank you for following me Face Book and Twitter.

And thank you for watching, and for all of your kind get well soon messages, they are all appreciated.

May I wish you all a Happy and Peaceful New Year.

Simulating Jet Streams on Jupiter

Simulating Jet steams on Jupiter from Richard Pearson on Vimeo.

A University of Alberta researcher has successfully generated 3-D simulations of deep jet streams and storms on Jupiter and Saturn, helping to satiate our eternal quest for knowledge of planetary dynamics. The results facilitate a deeper understanding of planetary weather and provide clues to the dynamics of Earth’s weather patterns evidenced in jet streams and ocean currents.

“Since the pioneering telescope observations of Giovanni Cassini in the mid-17^th century, stargazers have wondered about the bands and spots of Jupiter,” says Moritz Heimpel, a physics professor at the U of A whose study produced the simulations of the observable phenomena. The bands he references indicate jet streams while the spots signify storms; Heimpel is studying the dynamics between the two.

“At its core, our research is curiosity-based, and our ideas are driven by observations.” —Moritz Heimpel

“The average citizen can now pick up a backyard telescope and see the structures that we write about today. However, even in the present age with the Cassini spacecraft orbiting Saturn and the Juno craft approaching Jupiter, there is considerable debate about the dynamics of the atmospheres of the giant planets.” Heimpel notes that despite 350 years of observation, the origin and dynamics of planetary jet streams and vortices or planetary storms remain debated.

Shallow weather layer simulations have struggled to adequately reproduce the jet streams on Jupiter and Saturn, and previous deep-flow models have not reproduced vortices. Heimpel and his colleagues have taken this challenge to the next level, using fluid dynamics equations and supercomputers to produce more realistic simulations that give insight into the origin of both features. 

 

“One of the big questions we have is how deep these structures go,” says Heimpel. “These storms are embedded in these jet streams, and there’s no solid surface to stop them. Our simulations imply that the jet streams plunge deep into the interior, while the storms are rather shallow.” 

Unlike great storms on Earth, which eventually lose steam after encountering land mass, planetary storms can continue for centuries.

Where to find the 'Chrismas Comet' Catalina 20 - 29 December

Comet Catalina is now moving out of Virgo and into the adjacent constellations of Bootes (The Herdsman) and heading for it’s New Years day close approach to the bright star Arcturus.

Northern sky mapped in the light of Neutral Hydrogen

Radio astronomers from Bonn University and the Max-Planck-institute fur Radio astronomy have reached a scientific milestone with their publication in the January issue of the international science journal Astronomy & Astrophysics.

 

One of the world's largest fully steerable radio telescopes, the Effelsberg 100-m dish, sun/eyed the entire northern sky in the light of the neutral hydrogen (HI) 21-cm line. This effort, led by Jurgen Kerp (Argelander Institute for Astronomy) and Benjamin Winkel (Max Planck-institute fur Radio astronomy), began in 2008 and has culminated today in the initial data release of the Effelsberg-Bonn HI Survey (EBHIS). Funded by the German Research Foundation (Deutsche Forschungsgemeinschaft - DFG), the EBHIS data base is now freely accessible for all scientists around the world. In addition to the now released Milky Way data, the EBHIS project also includes unique information about HI in external galaxies out to a distance of about 750 million light years from Earth. Hydrogen is THE ELEMENT of the universe. Consisting of a single proton and an electron it is the simplest and most abundant element in space.

 

One could almost consider the universe as a pure hydrogen universe, albeit with some minor "pollution" by heavier elements, among these carbon, the fundamental component of all organisms on Earth. The 21-cm line is a very faint but characteristic emission line of neutral atomic hydrogen (or HI). It is not only feasible to detect the weakest signals from distant galaxies with the 100-m Effelsberg antenna, but also to determine their motion relative to Earth with high precision.

 

A special receiver was required in order to enable the EBHIS project. With seven receiving elements observing the sky independently from each other, it was possible to reduce the necessary observing time from decades to about five years only.

 

Field Programmable Gate Array (FPGA) spectrometers were developed within the course of the EBHIS project, allowing real time processing and storage of about 100 million individual HI spectra with consistently good quality.

 

The individual HI spectra were combined using high-performance computers into a unique map of the entire northern sky and provide unsurpassed richness in detail of the Milky Way Galaxy gas.

 

Astronomy students at Bonn University had unique access to the pre-release EBHIS data. In 2013 the European Space Agency (ESA) signed a memorandum of understanding with the Bonn HI radio astronomers. ESA was granted exclusive access to EBHIS data for their Planck satellite mission and, in return, Bonn students were given unique access to Planck data for their thesis projects. Twelve Bachelor, nine Master, and five Doctoral thesis projects have been successfully completed since 2008.

The Star of Bethlehem

 

(C) BBC TV

Some planetary conjunctions can be a wonderful sight. On the morning of 9 January 2016 Venus will be just 1 degree south of Saturn in the dawn sky; something to look forward too. There have been others previously of course, and there will be actual planetary Occultations to come.

 

So with the four bright planets Venus, Mars and Jupiter on view in the morning sky, its inevitable that the Sky at Night team, Prof. Chris Lintott and Dr Maggie Aderin-Pocock should make a program about the ‘Star of Bethlehem.’ The program will not be broadcast until 27 December, and there will be no program in January due to BBC Stargazing Live, so the program will not return in until mid March 2016.

 

This program from the BBC archives takes a look at all the evidence for the cause of ‘The Star of Bethlehem.’

 

There was a triple conjunction of Jupiter and Saturn in 146 -145 BC, in Cancer. There are no surviving observations of it, but it must have been interesting to watch. The closest approach took place on 18 October 146 BC when the two were separated by 11 minutes of arc, which is around one-third the apparent diameter of the full Moon. The next approach, on 10 December, brought the two within 15 minutes of arc of each other; during the third, on 4 May BC 145, they were a mere 10 minutes of arc apart - nearly, though not quite, close enough for the two to fuse into one object from the viewpoint of the naked-eye observer.

 David Hugh's notes that during the triple conjunction of 7 BC, the only one which falls within our ‘star of Bethlehem’ period, the two planets were in Pisces, the Fishes. On 27 May 7 BC, they were one degree from each other, so that they were well separated. Then they moved apart, to approach each other again during October; on the 6th of that month they were again one degree apart. Another separation, and a final approach on 7 December, again at a range of just over one degree. After that they moved apart relatively quickly.

 

It is evident that this triple conjunction was less spectacular than that of 145 BC, and in fact it was not spectacular at all. Jupiter is always brilliant, but Saturn was more or less at its faintest, with a magnitude of+0.5, slightly inferior to the star Procyon in Canis Minor (the Little Dog) and two whole magnitudes fainter than Sirius.

Antique Telescopes : Manchester Astronomical Society

9 December: ESA and Airbus Defence Space sign contract to build JUICE

Lecture by Dr Leigh Fletcher, University of Oxford

The JUICE (JUpiter ICy moons Explorer) was selected in May 2012 as the first Large-class mission within ESA's Cosmic Vision 2015–25 programme, and is planned for launch in 2022 to arrive at the giant planet in 2030.

The Jupiter Icy Moons Explorer (JUICE), ESA’s first large-class mission within the Cosmic Vision Program 2015-2025, was formally adopted in November 2014. The overarching theme for JUICE is the emergence of habitable worlds around gas giants. The mission will perform detailed investigations of Jupiter and its system with particular emphasis on Ganymede as a planetary body and potential habitat. At Ganymede, the mission will characterize in detail the ocean layers; provide topographical, geological and compositional mapping of the surface; study the physical properties of the icy crust; characterize the internal mass distribution, investigate the exosphere; study Ganymede’s intrinsic magnetic field and its interactions with the Jovian magnetosphere. For Europa, the focus will be on the non-ice chemistry, understanding the formation of surface features and subsurface sounding of the icy crust over recently active regions. Callisto will be explored as a witness to the bombardment history of the early solar system.

People from left to right:
Vincent Poinsignon, JUICE Project Manager, Airbus Defence and Space;
Eric Béranger, Head of Programmes Space Systems, Airbus Defence and Space;
Alvaro Giménez, Director of Science Programmes, European Space Agency;
Michael Menking, Director of Earth Observation, Navigation & Science, Airbus Defence and Space;
Giuseppe Sarri, JUICE Project Manager, European Space Agency.

20 Years of Exoplanets

Not a single confirmed planet outside the Solar System had been detected before the year 1990. But, remarkably, we now know of thousands and have studied many in surprising detail. This ESOcast takes a look at how ESO’s observatories in Chile have been at the forefront of this enormous expansion in knowledge, and how their state-of-the-art instruments are continuing to discover and study the extraordinary diversity of exoplanets.

15 December BBC 1: Stargazing Live

Join Brian Cox and Dara O Briain on 15 December as British astronaut Tim Peake launches to the International Space Station. On 12 January Stargazing returns to Jodrell Bank for a new series.

Best ever image of red hypergiant star VY Canis Majoris

A team of astronomers using ESO’s Very Large Telescope (VLT) has captured the most detailed images ever of the hypergiant star VY Canis Majoris. These observations show how the unexpectedly large size of the particles of dust surrounding the star enable it to lose an enormous amount of mass as it begins to die. This process, understood now for the first time, is necessary to prepare such gigantic stars to meet explosive demises as supernovae.

VY Canis Majoris is a stellar goliath, a red hypergiant, one of the largest known stars in the Milky Way. It is 30–40 times the mass of the Sun and 300 000 times more luminous. In its current state, the star would encompass the orbit of Jupiter, having expanded tremendously as it enters the final stages of its life.

The new observations of the star used the SPHERE instrument on the VLT. The adaptive optics system of this instrument corrects images to a higher degree than earlier adaptive optics systems. This allows features very close to bright sources of light to be seen in great detail [1]. SPHERE clearly revealed how the brilliant light of VY Canis Majoris was lighting up clouds of material surrounding it.

And by using the ZIMPOL mode of SPHERE, the team could not only peer deeper into the heart of this cloud of gas and dust around the star, but they could also see how the starlight was scattered and polarised by the surrounding material. These measurements were key to discovering the elusive properties of the dust.

Careful analysis of the polarisation results revealed these grains of dust to be comparatively large particles, 0.5 micrometres across, which may seem small, but grains of this size are about 50 times larger than the dust normally found in interstellar space.

Throughout their expansion, massive stars shed large amounts of material — every year, VY Canis Majoris sees 30 times the mass of the Earth expelled from its surface in the form of dust and gas. This cloud of material is pushed outwards before the star explodes, at which point some of the dust is destroyed, and the rest cast out into interstellar space. This material is then used, along with the heavier elements created during the supernova explosion, by the next generation of stars, which may make use of the material for planets.

Until now, it had remained mysterious how the material in these giant stars’ upper atmospheres is pushed away into space before the host explodes. The most likely driver has always seemed to be radiation pressure, the force that starlight exerts. As this pressure is very weak, the process relies on large grains of dust, to ensure a broad enough surface area to have an appreciable effect [2].

“Massive stars live short lives,” says lead author of the paper, Peter Scicluna, of the Academia Sinica Institute for Astronomy and Astrophysics, Taiwan. “When they near their final days, they lose a lot of mass. In the past, we could only theorise about how this happened. But now, with the new SPHERE data, we have found large grains of dust around this hypergiant. These are big enough to be pushed away by the star’s intense radiation pressure, which explains the star’s rapid mass loss.”

The large grains of dust observed so close to the star mean that the cloud can effectively scatter the star’s visible light and be pushed by the radiation pressure from the star. The size of the dust grains also means much of it is likely to survive the radiation produced by VY Canis Majoris’ inevitable dramatic demise as a supernova [3]. This dust then contributes to the surrounding interstellar medium, feeding future generations of stars and encouraging them to form planets.

Comet Catalina ‘The Christmas Comet’: Where to see it

On 1st December comet Catalina lies in the SE sky before sunrise and may first be glimpsed on 9 December when it lies a little to the left of Iota Virginis with a magnitude of +4.8. Iota is also of the 4^th magnitude. ‘the Christmas comet’ continues to grow brighter as it moves up through Virgo into Bootes (the herdsman) during the month The best photo-opportunity will be on New Year’s Eve when comet Catalina will be very close to Arcturus, the brightest star in Bootes. Its magnitude will be 4.8 so it will be visible to the unaided-eye at this stage.

Catalina continues to climb higher into the northern sky, and reaches its second photo opportunity on 15 January 2016 when the 5 mag comet will be a little left of the bright star Benetnash, the bottom star of the ‘Plough’ in Ursa Major the great bear. On the evening of the 31 January Catalina will be to the right of Polaris in the zenith. The comet’s brightness will then have faded to +6 below naked-eye visibility.

Small telescopes will now be need to show the comet well. Catalina passes down through the fainter constellation Camalopardalis, fading all the time, and moves into Perseus when its magnitude will be +9.

7/8 December | Catalina photo opportunity

On the morning of 7/8 December comet Catalina will be close to the faint galaxy NGC 5534 | RA 14h 17m 40.258s Dec -07 25’ 03.02”

 

 

 

 

Pluto update: the Mountainous Shoreline of Sputnik Planum

In this highest-resolution image from NASA’s New Horizons spacecraft, great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright. Several sheer faces appear to show crustal layering, perhaps related to the layers seen in some of Pluto’s crater walls. Other materials appear crushed between the mountains, as if these great blocks of water ice, some standing as much as 1.5 miles high, were jostled back and forth. The mountains end abruptly at the shoreline of the informally named Sputnik Planum, where the soft, nitrogen-rich ices of the plain form a nearly level surface, broken only by the fine trace work of striking, cellular boundaries and the textured surface of the plain’s ices (which is possibly related to sunlight-driven ice sublimation). This view is about 50 miles wide. The top of the image is to Pluto’s northwest.

Credit: NASA/JHUAPL/SwRI

Last Updated: Dec. 4, 2015

Mt Etna Eruption lights up Sicilian sky

Taken on December 3 by Sicilian photographer Marco Restivo, 29, these incredible pictures show Europe's tallest active volcano spitting fire and sending plumes of smoke into the air.

This is the first eruption to reach the surface of Etna's Voragine crater in two years.

Snapper Marco used photo editing software to overlap five images to create one single picture which shows volcano lighting under a cloud of dense smoke.

The Italian also created a time-lapse video of the eruption using 60 images which were taken at an altitude of 1,800 metres He said: “The eruption column, which is made up of hot volcanic ash, was very high and powerful and created the phenomena of lightning.

“On Etna you are surrounded by a primeval environment and you can feel the earth alive - it's a really amazing experience.

“People have been fascinated by the size of the eruption and many do not believe it when they see my pictures.”

Look out for Saturn in the ‘Dawn sky’ this Christmas

Dated 27 September, this wonderful image of Saturn is by Australian astrophotographer Trevor Barry using a Newtonian 16 inch telescope.

Saturn was in conjunction with the Sun on 30 November, and will now slowly begin to reappear in the morning sky from 14 December.

15 December 2015  RA: 16h 30.7m Dec –20 12’ Magnitude +0.5. Equatorial diameter 15.2” arc seconds. System I: 25.8 degrees.

24 December 2015  RA 16h 35.5m Dec –20 22’ Mag +0.5 System I: 187.8 degrees.

Jan 3 2016   RA 16h40.2m Dec –20 31’ Mag +0.5 System I: 349.9 degrees.

Image © Trevor Barry

 

 

South > Top. North > Bottom.

West > Left. East> Right.

 

Eta Carinae: a very large ‘Hadron collider’

ETA (η) Carinae is the colliding wind binary with the highest mass-loss rate in our Galaxy and the only one in which hard X-ray emission has been detected.

η Carinae is therefore a primary candidate to search for particle acceleration by probing its gamma-ray emission.

A bright gamma-ray source is detected at the position of η Carinae. Its flux at a few 100 MeV can be modelled by an extrapolation of the hard X-ray spectrum towards higher energies. The spectral energy distribution features two distinct components. The first one extends from the keV to GeV energy range, and features an exponential cut-off at ∼ 1 GeV. It can be understood as inverse Compton scattering of ultraviolet photons by electrons accelerated up to γ ∼ 10**4 in the colliding wind region. The expected synchrotron emission is compatible with the existing upper limit to the non-thermal radio emission. The second component is a hard gamma-ray tail detected above 20 GeV. It could be explained by π0 -decay of accelerated hadrons interacting with the dense stellar wind. The ratio of the fluxes of the π0 to inverse Compton components is roughly as predicted by simulations of colliding wind binaries. This hard gamma-ray tail can only be understood if emitted close to the wind collision region. The energy transferred to the accelerated particles (∼ 5% of the collision mechanical energy) is comparable to that of the thermal X-ray emission.

The electron spectrum responsible for the keV to GeV emission was modelled and the observed emission above 20 GeV strongly suggests hadronic acceleration in η Carinae. These observations are thus in good agreement with the colliding wind scenario proposed for η Carinae.

Image:

Composite image shows portraits of the massive star system Eta Carinae as seen in low-energy gamma rays (left), visible light (middle) and high-energy gamma rays (right). The highest energy gamma rays are believed to be generated when protons accelerated in the star system’s winds collide with charged atoms in the wind, in something like a scaled-up version of the Large Hadron Collider.
Credits: ISDC/Walter, NASA, Fermi, INTEGRAL

Comets on show in 2016

2013 US10 (Catalina) may be at its brightest in early January, having continued to approach the Earth after perihelion in 2015 November. It is well placed, reaching within 10° of Polaris at the end of January, though by then it is fading rapidly. It passes just over a degree from 9th magnitude globular NGC 5466 over January 5/6; two degrees from galaxy M101 over January 15/16 and is close to open cluster NGC 1502 on February 22/23.

 

 

 

9P/Tempel was first observed in 1867, but was lost between 1879 and 1967 following an encounter with Jupiter in 1881, which increased the perihelion distance from 1.8 to 2.1 au. Further encounters in 1941 and 1953 put q back to 1.5 au and calculations by Brian Marsden allowed Elizabeth Roemer to recover it in 1967. Alternate returns are favourable, but an encounter with Jupiter in 2024 will once again increase the perihelion distance to 1.8 au. It was the target for the Deep Impact mission, with the Stardust spacecraft subsequently passing by the comet. The comet could come into visual range in March, and remains visible for UK observers until June. It could be at its brightest around 11th magnitude in early July, when it passes south of the celestial equator, and Southern Hemisphere observers will be able to follow it as it fades.

 

29P/Schwassmann-Wachmann is an annual comet that has outbursts, which over the last decade seem to have become more frequent. The comet had one of its strongest outbursts yet recorded in early 2010. Richard Miles has developed a theory that suggests that these outbursts are in fact periodic, and arise from at least four independent active areas on the slowly rotating nucleus. The activity of the active areas evolves with time. The comet is an ideal target for those equipped with CCDs and it should be observed at every opportunity. The comet is at a southern declination, reaching opposition in Scorpius in June and passing through solar conjunction at the end of December.

 

 

45P/Honda-Mrkos-Pajdusakova has had several close encounters with Jupiter, the most recent in 1983 which made dramatic changes to ω and Ω. The perihelion distance has steadily decreased and is close to the smallest it has been for the last 200 years, though is now increasing again. It can approach quite closely to the Earth and did so at the last return in 2011 (0.06 au) and is on its way to another close approach post perihelion, in 2017 (0.08 au). At present the MPC only lists eight approaches closer than 0.06 au out of 20 passes closer than 0.1 au, and nine of these are by five periodic comets. It can also pass close to Venus and passed at 0.085 au in 2006, getting even closer in 2092. The comet brightens rapidly in November, but it is well south of the celestial equator. For northern observers there may be a short period when it might be visible at the close of the year, when it is at perihelion and perhaps 7th magnitude.

 

252P/LINEAR is an earth approaching comet and makes a very close approach on March 21 when it passes 0.036 au from our planet. This is the fifth closest cometary approach on record, and it is by virtue of this that this otherwise faint comet might come within visual range for a few weeks. It races north after closest approach, and for northern observers there is an observing window of about a week from March 30 when it might be seen, as the peak magnitude is predicted at 10 and it fades very quickly.

2013 X1 (PanSTARRS) could be 10th magnitude at the beginning of the year and well placed in the evening sky for northern hemisphere observers. It is rapidly moving south however, and after mid February will be lost to view. After solar conjunction Southern Hemisphere observers will be able to observe it from around April until September, with the comet brightest at around 7th magnitude in June.

The December 2015 issues of Astrophography Ezine

The new magazine is now available which is full of tips and advice for amateur astronomers looking to image the best sights in the night sky. Highly recommended.

Europe’s LISA Pathfinder (LPF) spacecraft set for December launch

The countdown is on for the launch of Europe’s LISA Pathfinder (LPF) spacecraft.

"Due for launch on the Vega Rocket in early December 2015, launch VV06 will be a landmark event for the UK Space community.

LPF is the first scientific spacecraft to have been led and launched by the UK Space industry since Giotto was launched in 1985.

The aim of the mission is to perform in orbit testing of cutting edge technology designed to enable detection of gravitational waves in space. While the spacecraft won’t actually perform this detection, it is paving the way for a future mission enabling scientists to expand their understanding of the universe and to prove whether the predictions made by Einstein about gravitational waves are indeed true. To do this, LPF will be attempting to control the relative positions of two small gold and platinum test masses effectively levitating within the spacecraft.

The spacecraft itself has been designed, built and tested by the UK’s own Airbus Defence & Space (formally Astrium) at the company’s Stevenage base in Hertfordshire. The UK led team has included contributions from both industry and academia (University of Birmingham, University of Glasgow and Imperial College London) and contributions from around the globe including Europe and the US.

The original contract for LPF was signed by Airbus Defence & Space and the European Space Agency back in 2004 with an original launch date of 2009. However, as with many cutting edge developments, the mission has faced its fair share of hurdles along the way including late changes to the technologies behind the micro-propulsion subsystem and the launch restraint of the test masses.

Back to 2015 and it has been all systems go for the LPF team a number of who have spent much of the year living and working away from home and family in order to see the launch achieved. The spacecraft recently completed the final test campaign at the IABG facility in Munich, Germany during which it underwent space environment testing (or thermal test to those in the business) followed by a simulation of the conditions it will face during the launch within the rocket housing (known as an acoustic test). In addition the final pieces of the jigsaw were put in place with the integration of the main science instrument (the LISA Technology Package) containing the two gold test masses which form the beating heart of the technology demonstration.

The spacecraft has now arrived at the launch site, Guiana Space Centre, in Kourou, French Guiana. Arriving in style on board the enormous Antonov AN-124 aircraft, the spacecraft departed from London’s Stanstead Airport on the evening of October 7th and arrived in the early hours at Cayenne after a brief refuelling stop in the Azores. Final preparations for the upcoming launch are now well under way.

Following the launch, the spacecraft, which is formed of two parts; the main scientific spacecraft and a propulsion module, will make its way to a place known as L1, some 1.5 million km from the Earth. The journey to L1 will take approximately 50 days. Once there, the two halves of the spacecraft will separate from one another, the propulsion module having served its purpose to propel the science spacecraft from the 1540km elliptical parking orbit that the Vega rocket delivered it to and into orbit around the L1 point. The nominal mission is relatively short, 6 months of technology demonstration in orbit and potentially a further 6 months of mission extension should there be a need to perform further tests. Following the results from LPF, the Space community is expected to forge ahead with plans for the full LISA mission, expected to comprise three spacecraft flying in a giant triangular formation creating the largest Space based interferometer ever seen."

Vicki Lonnon, LISA Quality Assurance Engineer | Ian Honstvet, Project Manager.

Carbon Exchange and Loss Processes on Mars

This graphic depicts paths by which carbon has been exchanged between Martian interior, surface rocks, polar caps, waters and atmosphere, and also depicts a mechanism by which carbon is lost from the atmosphere with a strong effect on isotope ratio.

Carbon dioxide (CO2) to generate the Martian atmosphere originated in the planet's mantle and has been released directly through volcanoes or trapped in rocks crystallized from magmas and released later. Once in the atmosphere, the CO2 can exchange with the polar caps, passing from gas to ice and back to gas again. The CO2 can also dissolve into waters, which can then precipitate out solid carbonates, either in lakes at the surface or in shallow aquifers.

Carbon dioxide gas in the atmosphere is continually lost to space at a rate controlled in part by the sun's activity. One loss mechanism is called ultraviolet photodissociation. It occurs when ultraviolet radiation (indicated on the graphic as "hv") encounters a CO2 molecule, breaking the bonds to first form carbon monoxide (CO) molecules and then carbon (C) atoms. The ratio of carbon isotopes remaining in the atmosphere is affected as these carbon atoms are lost to space, because the lighter carbon-12 (12C) isotope is more easily removed than the heavier carbon-13 (13C) isotope. This fractionation, the preferential loss of carbon-12 to space, leaves a fingerprint: enrichment of the heavy carbon-13 isotope, measured in the atmosphere of Mars today.

NASA Press Release: 24 November 2015