James Clerk Maxwell Telescope: 30 years later

12 September 2017

Interview with

Wayne Holland, UK Astronomy Technology Centre

Now what do you remember about the 1980s? Brick-sized mobile phones? The ability of the world to function without facebook? Apart from those more trivial things, the 1980s also marked the birth of one of a telescope that has helped to us to see our place in the Universe much more clearly. The James Clerk Maxwell Telescope is now celebrating 30 years of gazing skywards, and, beginning in the 1980s, Izzie Clarke’s been hearing what it’s helped scientists to see...

Izzie - In 1987, the Bangles had us Walking Like an Egyptian, we were Living on a Prayer with Bon Jovi, and Star Trek: Next Generation set out on their own mission to boldly go where no-one has gone before… and they weren’t the only ones...

Wayne - This is one of the very first telescopes that was ever built for this particular wavelength. The technology was difficult, and we were borrowing ideas from the optical and the radio, and almost like pushing them together to try and make the technology work.

Izzie - That’s Wayne Holland. He’s a Professor and astronomer for the UK Astronomy Technology Centre in Edinburgh. And this year, scientists are celebrating 30 years of the James Clerk Maxwell Telescope.

Wayne - It doesn’t look like a conventional telescope. It’s almost like sitting in a large hut on top of a mountaintop on the big island of Hawaii. The instruments that we had on the back of the telescope were very simplistic. We would painstakingly move this one pixel from point to point on the sky and then we would try and basically build up an image. It was almost like joining up the dots almost of the actual signals that we were seeing. It would take an incredibly long amount of time just to build up a very small image of a fairly compact source like a nearby star or something like that.

Izzie - The James Clerk Maxwell Telescope, known as JCMT for short, became the world’s most successful single dish telescope working at submillimetre wavelengths. This is a region that’s roughly between the infrared and the radio part of the electromagnetic spectrum.

Wayne - It allows us to basically study light that’s emitted from very cold regions of space. Regions, for example, where galaxies, stars and planets may be forming.

Izzie - Stars form in these dense clouds of dust and gas, and this was one of the key investigations for JCMT in the 80s and 90s. This project called UKT 14 set out to explore these star formations, mapping the sky one pixel at a time.

Wayne - We found a what became known as protostars. It’s a term that was coined in the late 70s, but protostars were never really observed until the late 1980s, early 1990s, and they just look like blobs on the sky. You can work out their characteristic temperature and, in some cases, some of the constituent chemical elements they’re made of so you can produce a spectrum.

As time went on we learnt more and more about these objects. What were able to do is to place them in an evolutionary sequence, so some of the very earliest star forming regions were called starless cores, and then they became protostars, and then more evolved stars and then, eventually, stars like our own Sun are called main sequence stars. These early observations made a real inroad into understanding the whole star formation process.

Izzie - But, after a while, it was time for upgrade and, in 1997 came SCUBA, the world’s first submillimetre camera. And whilst this camera created images with just 100 pixels, SCUBA brought about the submillimetre revolution in astronomy…

Wayne - It was necessary to really push the sensitivity limits beyond our own galaxy. The Hubble Space Telescope had been launched and it produced a wonderful picture called the Hubble Deep Field of some very early galaxies. So what we did, we pointed out telescope with a SCUBA camera on the back at this particular point of sky and what we found was another population of galaxies, so the galaxies that we were seeing didn’t coincide with the ones that Hubble was seeing.

What SCUBA and JMT discovered was a completely new population of distant luminous galaxies that were completely invisible to the optical telescopes. The stars in these galaxies are, again, are enshrouded in cold gas and dust, but they shine brightly, again, at longer wavelengths as a result of heating this material up. What we believed we were seeing at the time has gone on to be proved correct. We’re seeing these galaxies something like 10 billion years ago and so looking at these very early galaxies, again, tells us a great deal about galaxy evolution and how these galaxies evolved to be the galaxies that we can see today. The giant electrical galaxies that Hubble and other optical telescopes see.

Izzie - This was one of JCMT’s biggest discoveries, and these young active galaxies are now known as SCUBA galaxies. Although SCUBA has made so many pioneering findings, it was obvious that by the turn of the century an even-more-sensitive camera was required, something that could look at wider parts of the sky - SCUBA 2...

Wayne - Since the commissioning of SCUBA 2, which was about 6 or 7 years ago now, this new wide field camera, it’s mainly been carrying out surveys, so large areas of sky. The first generation surveys that ran from 2012 till 2015 were surveying galaxy clusters, star formation regions. Also, a survey that I was involved in was looking at discs around nearby stars and looking for evidence of whether solar systems similar to our own are actually present around nearby stars. The range of astronomy that we can do with this telescope is immense.

Izzie - Potentially, do you think you could see the beginning of another solar system similar to our own forming?

Wayne - There’s been lots of work recently over the last decade on extrasolar planets. But what I’m interested in is actually seeing if the architecture of our own solar system: the 8 planets, the comets, asteroids, and that kind of thing, whether that kind of architecture can exist around other stars other than our own sun, and answer the question just how typical is our solar system around other stars.

You can do that by looking at evidence of discs and belts, and we’ve detected and imaged a number of these around nearby stars, some quite famous stars like Vega for example. And that gives you an idea as to what kind of environments there are around these stars. You can’t see the planets directly by any means, but you can infer their presence by looking at structures within the discs that we see as well. So it’s quite an exciting area of astronomy that’s been developing over the last few years.

Add a comment