Custom-built robot will study a very special star

When you need 200 consecutive days to observe a special star like Beta Pictoris, it helps to be able to build your own telescope, as UCT and South African Astronomical Observatory (SAAO) PhD fellow Blaine Lomberg and his collaborators have done.

The custom-built instrument, called bRing (short for Beta Pictoris b Ring), is now nestled on the plateau near the Southern African Large Telescope (SALT) in Sutherland.

From 1 April 2017 to January 2018, Lomberg and his collaborators from Leiden Observatory, Netherlands, will study Beta Pictoris, a white dwarf star that is 63.4 light years away in the constellation Pictoris.

Beta Pictoris can be seen with the naked eye in the southern skies. With a luminosity nine times greater than the Sun, it’s almost twice as massive. But in cosmic evolutionary terms, it’s a mere two-month-old baby compared with our middle-aged Sun.

This team of researchers is hoping to find more evidence of a giant, ringed planet orbiting Beta Pictoris. Because of geometry, the giant planet can’t be seen. However, astronomers know there’s something large there from the effects on the disc of debris around Beta Pictoris.

Dust provides the clues

An important chapter in this story began in 1981 when astronomers noticed that the brightness of Beta Pictoris had diminished. Early observations showed a warp of the dust disc, a secondary inclined disc and comets falling onto the star – all tell-stale signs of a massive planet nearby.

Observations in 2003, 2008 and 2009 proved that there was indeed a large presence near Beta Pictoris, and astronomers believed that it was this huge object that had passed in front of the star, diminishing its brightness.

The 200 days of study coming up are significant because it’s anticipated that during this time the massive planet will pass almost directly between Beta Pictoris and the Earth.

A star encircled by dusty discs is interesting, says Lomberg.

“Imagine a newborn star forming from a giant cloud of gas and dust. When the cloud collapses under its own gravity, the star starts forming while rotating around itself in a specific direction. From the debris of the cloud, a disc of gas and dust forms around the star.”

Dust discs are associated with quite young stars, and this matter, pushed together, is how planets are sculpted.

“So we’re doing a survey of something that’s quite young in astronomically evolutionary stages. We’re excited because [Beta] Pictoris could be an ideal laboratory to look at how the universe evolved.”

If there are any changes to the brightness of Beta Pictoris, the information will be relayed in real-time to the bRing team, who will trigger a host of observations using larger aperture telescopes like SALT and more advanced instrumentation to study the ring system in-depth.

A few seconds’ glimpse at the chemical composition of the rings is all that’s needed, says Lomberg.

“I can do a complete chemical analysis of what those are composed of: how it’s formed and what the matter is and perhaps we could find exo-comets or moons to tell us how the system is forming. This will give us further understanding of our own solar system.”

Lone star study

The problem was asking an observatory to dedicate 200 days for the team to look at just one star.

“That’s just wasn’t going to happen,” said Lomberg.

For unprecedented monitoring of just one star, the solution was to build their own telescope – and Lomberg just happens to be handy in this field. He studied physics at the University of the Western Cape and then studied and worked in the UK and had a stint at the Large Hadron Collider at CERN (the European Organisation for Nuclear Research).

“My interest has always been building things,” he said.

As technology in astronomy advanced, he became more and more interested in using and building instruments – and then doing the science. When he interviewed for a PhD project at UCT/SAAO, he knew he wanted to build an optical device, “taking the technology of the everyday and using it to do science”.

In this, Lomberg was part of a team lead by Leiden astronomer Matthew Kenworthy that included Remko Stuik, John Bailey and Patrick Dorval from Leiden University and Steve Crawford, Lomberg’s PhD supervisor at SAAO.

“bRing is a little silver box, a robotic, self-operating telescope. The two parts that move with bRing are its two shutters, or eyelids. It looks a bit like an owl,” he quipped fondly.

The team built bRing from everyday materials, but the design itself is very customised.

“Every part inside has been built by the bRing consortium – roughly six months to build with a lot of intensive work to get it done on time.”

Importantly it houses a “very fancy, customised software system”.

“As for the data, everything bRing gives us will be our responsibility to interpret,” said Lomberg. “bRing can store up to 124 gigabytes of raw data a night, so the volume is quite large.”

The instrument will provide Lomberg with a constant flow of information when it’s looking at the night sky.

“So suppose the brightness of Beta Pictoris changes; bRing will send an email in real time saying, ‘Hey, wake up, something interesting is happening to the star!’ ”

Monitoring night conditions

bRING finally installed at Sutherland. Photo Remko Stuik.

In addition to monitoring Beta Pictoris, bRing will also provide regular monitoring of the southern sky and the conditions of the night sky at the Sutherland observatory. The data will be available to local astronomers, allowing them to search for new phenomena and to monitor the performance of their own observations.

“It’s an exciting time for me,” said Lomberg. “I recently did some observations of Beta Pictoris with the SALT high resolution spectrograph and I hope to analyse this data to get a good baseline of the star. We know the star’s chemical composition right now and if anything passes by it, we’ll know that any new chemicals detected will be associated with whatever matter is passing the star.”