Astronomers drool at new map of Milky Way

The first data from the Gaia satellite was published on Wednesday. Astronomers from the University of Groningen's Kapteyn Astronomical Institute couldn't wait to get their teeth into it.

‘This is a very special day for me,’ says University of Groningen Professor of Astronomy Amina Helmi. She is giving a delayed lunchtime presentation for a group of colleagues on the first observations of the Gaia satellite, which has measured with great precision the colour, intensity and movement of a billion stars in the Milky Way. Helmi has been working on Gaia since the end of the 1990s: first planning the mission , then supervising the satellite’s construction and finally verifying the quality of the first observations. Now she can finally set to work – once she’s got the presentation out of the way that is.

An hour beforehand in the coffee corner of the Kapteyn Astronomical Institute – named after astronomer J.C. Kapteyn, the originator of one of the first maps of the Milky Way almost a century ago – Helmi and her research group sit watching a livestream by the European Space Agency (ESA), which built Gaia and is responsible for the data. The hour-long livestream is supposed to culminate in the publication of the first Gaia observations at 12:30 on the dot. But there are problems with the live YouTube connection and the programme is delayed.

Nerves

ESA has chosen an unusual approach. The institutions that fund a satellite usually have first dibs on the data, the rest of the world following later. ‘But Gaia was funded in full by the European Space Agency, ESA’, Helmi explains. ESA therefore decided to release its data immediately. ‘What is being published online now is some of the data from the first eighteen months of the Gaia mission’, says Helmi. ‘This means observations of more than a billion stars.’

Various speakers explain the mission. This is nothing new for the watching astronomers, whose nerves rise as 12:30 approaches. Nearly all of them have their laptops at the ready. At just after 12:30 the database doesn’t seem to be accessible. Will ESA wait until the live programme has finished? Then someone cries ‘it’s open!’ and all interest in the TV screen disappears.

A terabyte of files is downloaded and studied. How does it all work exactly? Analysis software has already been written, so the first data is imported. Images appear on the screen. There is rapid discussion on what can be seen. Then it’s time for Helmi to give her speech while the others begin the analysis.

Helmi studies how the Milky Way assumed its current form. From the path of stars, she can work out their origins and which ones come from the same ‘maternity ward’ – astronomers believe that stars are born in groups from gigantic dust clouds. ‘I’ll keep it brief today, because I want to get to work’, she says in her speech. She leaves the room, heading for her office. When does she expect the first results? She smiles. ‘I hope to know a bit more about the origin of certain stars tomorrow already.’