- RECENT HEADLINES
- Interstellar visitor tracked with LT
- Liverpool Telescope project shortlisted for Research Project of the Year
- Spectacular pictures added to LT Picture Gallery
- New Filter for RISE
- Quicker Daily Data Flow and Weekend Data Releases
Animation of 'Oumuamua (dot, circled) moving against background stars, made from frames obtained by the Liverpool Telescope on 26 October 2017.
Credit: Alan Fitzsimmons.
The interstellar object currently exiting the Solar System has finally been named as ‘Oumuamua, Hawaiian for "reach out for" (‘Ou) and "very first/in advance of" (mua mua). Thus the name "reflects the way this object is like a scout or messenger sent from the distant past".
‘Oumuamua was first detected on 19th October by Robert Weryk at the Institute for Astronomy at the University of Hawaii using data from the Pan-STARRS telescope on Mauna Kea in Hawaii. After a few nights of routine observation, preliminary calculations showed it to be on an open-ended hyperbolic orbit, i.e. to have entered the Solar System from interstellar space. Moreover, it had already made its closest approach to the Sun some weeks earlier and was now receding rapidly from the inner solar system.
Previously, the only other interstellar emissaries known to exist were a handful of microscopic dust particles discovered in 2014 in an aerogel dust collector brought back to Earth by the comet sample return mission Stardust. ‘Oumuamua on the other hand is estimated to be approximately 160 metres in diameter.
As this object is the first interstellar visitor observed, and was also rapidly becoming fainter as days passed, it become a race against time to observe ‘Oumuamua as much as possible before it passed out of detection range forever.
Alerts were circulated around the global astronomical community in the early hours of 25th October. Later that day veteran LT user Alan Fitzsimmons of Queens University Belfast requested a priority observation via the LT's database, and that night the LT began observing ‘Oumuamua. The animated gif of Fitzsimmons' 26th October observations is at the top of this page. Below is imagery from the William Herschel Telescope taken by Fitzsimmons on 28th Oct.
|‘Oumuamua (dot, centre) tracked against background stars by the William Herschel Telescope on 28th October.
Credit: Alan Fitzsimmons.
As a result of the efforts of astronomers around the world, not only has the orbit been definitively pinned down, but also aspects of its physical nature have been revealed. It's approximately 160 metres in diameter (assuming it reflects 10% of the sunlight falling on it), has a spin rate of possibly 6 hours, and has no cometary activity, despite getting as close as 0.25 AU from the Sun. Spectra are featureless and show its colour is red like a Kuiper Belt Object. That plus the lack of comet activity imply ‘Oumuamua must have spent so much time in the inner warmer reaches of its home star system that all volatiles had already disappeared by the time it left for interstellar space.
‘Oumuamua is now leaving the Solar System in the direction of the constellation Pegasus. By the time it leaves the Sun's influence, it will still be moving at over 26 kilometres per second, faster than any human-built spacecraft currently exiting our solar system. Efforts to trace its original stellar system, and where it might be headed in aeons to come, have so far been unsuccessful (the tiny errors in trajectory remaining after such a short arc of observations build up dramatically over millions of years). Given how relatively uncrowded stars are this far from galactic centre, ours might be the first Solar System ‘Oumuamua has encountered since it left home, possibly billions of years ago.
Left: Blue crosshair denotes ‘Oumuamua's position in the sky as it entered the Solar system centuries ago. Centre: Trajectory of ‘Oumuamua through the inner Solar system. Right: Position of ‘Oumuamua in the sky when it leaves the Solar system centuries hence. Credits: Left and right: Sky Safari 5 Pro & J. Marchant, Centre: JPL/NASA.
Liverpool John Moores University (LJMU) is one of six institutions shortlisted for Research Project of the Year: STEM in this year's Times Higher Awards.
The nomination has been awarded for the use of the SPRAT spectrograph in the study of the unique recurrent nova M31N 2008-12a in the Andromeda Galaxy. SPRAT (SPectrograph for the Rapid Analysis of Transients) was designed and built in late 2014 by the LJMU telescope group. It uses volume phase holographic gratings to maximise efficiency and has proved to be a powerful tool for transient classification with minimal human intervention.
Novae are binary systems consisting of a white dwarf that is accreting material from its companion star. The build-up of material on the surface of the white dwarf eventually leads to a thermonuclear explosion. Some so-called recurrent novae show repeated nova eruptions, but until recently the fastest recurrence timescales were in the tens of years, with the typical timescale being much longer. M31N 2008-12a has a nova eruption every year — an unprecedented recurrence timescale. The research team at LJMU's Astrophysics Research Institute, along with their collaborators, have demonstrated this is due to the combination of a huge companion star and the most massive white dwarf ever detected in such a system, leading to an extremely rapid mass transfer rate. The high cadence spectroscopy from SPRAT has been crucial in understanding the nature of this object, and it is predicted to be the first of a whole new class of "rapid recurrent novae". Since the nova event does not completely eject the accreted material, the white dwarf continues to increase in mass, with a catastrophic Supernova Ia event being its eventual fate. The conservative upper limit on the timescale for this event is 20,000 years.
A small sample of the 70+ LT images submitted to the Gallery. © 2017 Göran Nilsson and Wim van Berlo.
The pictures were made by taking archived greyscale IO:O data that had been observed through effectively red, green and blue filters, and combining them in various ways to produce colour images. Most of the original data had been requested over the years by UK schools via the National Schools' Observatory
This skilful post-processing was performed by Swedish amateur astrophotographers Göran Nilsson and Wim van Berlo.
Göran is a professor in animal physiology at the University of Oslo, and Wim is a physics and mathematics teacher in Stockholm. Both have been interested in astronomy and astrophotography for some time; Göran even built his own observatory in the Swedish countryside in 2014.
Living so far north has its drawbacks however when it comes to astrophotography in the summer. "During a four month period, from May through August, the sun hardly sets below the horizon, and it doesn’t get dark," says Wim. Göran, situated even further north, has the same experience: "The long light summer nights make astrophotography impossible for several months," he says.
To have something astronomy-related to do during this time, the two decided to use their growing astrophotography skills to process exposures that were freely available from the Liverpool Telescope's Data Archive. Together they sifted through all available data for each of the objects they chose, stacking and combining the frames. Göran used the program Nebulosity for stacking, following up with Adobe Photoshop for final contrast enhancements that reveal hitherto unseen fine detail. Wim performed the same tasks entirely with the single package PixInsight.
The result is over seventy stunning full-colour pictures of famous and some not-so-famous astronomical objects. We are certainly delighted with the pictures, and thank Göran and Wim for allowing us to host their work on our website.
[UPDATE (26 July): The filter has now been changed. See the RISE instrument page for further details.]
The RISE fast-readout camera is having its "V+R" filter replaced with a 720 nm long-pass filter on 26th July 2017. This is being done to enhance the capabilities of the camera with regard to measurement of exoplanet transits around late-type, red dwarf stars.
More details of the filter switch can be found in the filter section of the RISE instrument page here.
© Tomas Castelazo, www.tomascastelazo.com / Wikimedia Commons /
CC BY-SA 4.0
Regular telescope users may have noticed their daily data releases are coming a little earlier than in the past. Our data handling procedures have been updated to speed things up. Though the LT is designed to all be fully automated, to date we have deliberately inserted one manual break-point in the data flow such that after all the data are pipeline processed they are not released to you until one of us has had a look through all the night’s data as a quality assurance check. Experience has shown however that for the few occasions when this procedure has identified an instrument failure there are very many cases where we were unnecessarily delaying distribution of time sensitive data. Our new policy therefore is to release all data into the science archive as soon as possible each morning.
All science data are now typically available in both the Recent Data and searchable science archives between 09:30 and 10:30 UTC on the morning after they were observed. You will continue, as now, to get an email as soon as the data are available. Having removed the human interaction from the process, the data releases are now also being made seven days a week.
Those who use RISE at a high frame rate over several hours to generate large data sets may find their data arrive a little later than the estimate above. This is simply limited by the bandwidth from La Palma back to Liverpool. The data will be released as soon as the entire night’s observations have been transferred.
We are only here talking about the final science-ready archived data reductions. Quicklook continues to operate as before for those who need real-time, intra-night access to the data as soon as they are observed.
Besides better serving the time domain astrophysics community, there is one very obvious side effect to this change. We in the LT operations team will no longer see every frame taken and there is greater risk of telescope or instrument faults going un-noticed. The LT has a very wide array of in-house developed, automated telemetry processes that continually monitor system performance for us from hydraulic oil temperatures, through on-sky pointing residuals, instrument amplifier read noise and final archive image quality. These autonomous systems are effective at alerting us to many possible error states, but they will not detect everything. We are therefore now becoming much more dependent on you, the telescope users, to help run the observatory efficiently. We encourage all observers to routinely look at their new data and contact us about any problems you see. This is not only about technical faults. We have in the past been able to alert observers to mistakes in their phase 2 configurations that were revealed by poor data quality. Now the responsibility for ensuring that the data match expectations rests more heavily on all observers for their own data. We are always happy to advise on how best to exploit the telescope facilities if you get in touch to discuss your science objectives.