New space data serves as ‘complete step change’ in understanding of our Universe



Space scientists have today announced the discovery of a ‘super Jupiter’ orbiting a white dwarf, the first detected using direct observations with the European Space Agency (ESA)’s Gaia mission.

The discovery forms part of a treasure trove of data made available in Gaia’s Data Release 3, which provides the most detailed survey of our galactic neighbourhood to date.

Observations made by the Gaia observatory, which orbits a point in space about 1.5 million km from Earth, will allow astronomers to create the most accurate and complete multi-dimensional map of the Milky Way and better understand our place in the Universe.

Martin Barstow, Professor of Astrophysics and Space Science at the University of Leicester and Director of Strategic Partnerships for Space Park Leicester, is part of the Gaia collaboration to have co-authored multiple papers using the new data.

Other highlights of Data Release 3 include description of ‘starquakes’, stellar DNA and a new binary star catalogue of more than 800,000 binary systems. Before Gaia launched in 2013, only around 30,000 binaries were known in our galaxy.

Professor Barstow said: “Gaia data has been moving through astronomy like a tidal wave. It’s the most productive observatory we have available to use right now, and it’s transforming both astronomy and our understanding of the Universe.

“This Data Release 3 is a complete step change. All the data we have catalogued using spectra – stellar distances, ages, composition, and more – adds an extra dimension to what we know about the stars in our galaxy, and represents a huge leap forward.”

Data reveals a ‘super Jupiter’ companion

Observations of exoplanets orbiting white dwarfs is notoriously difficult. White dwarfs are the core remnant of stars not massive enough to become a black hole or neutron star.

However, by analysing the motion of the metal-rich white dwarf WD 0141-675 and noting a ‘wobble’ in its orbit, researchers inferred the existence of a companion object with a mass around nine times that of Jupiter. Too small to be a star, this must be an exoplanet.

This ‘super Jupiter’ is only the third known exoplanet to orbit a white dwarf, and makes WD 0141-675 the closest white dwarf to Earth to host a planet.

Stars in their eyes: Gaia more than doubles number of known binaries
Gaia’s Data Release 3 also expands astronomers’ understanding of binary systems, where two stars are gravitationally bound to one another. Sirius, the brightest star visible from Earth (after our Sun), is a binary system comprising a main sequence star, Sirius A, and a faint white dwarf companion, Sirius B.

These new datasets both refine the stellar catalogue of known binaries and add many more new such systems, bringing the total of known binary systems from around 300,000 before Data Release 3 to more than 800,000. Researchers detect binaries using Gaia’s radial velocity spectrometer and a variety of techniques;

1. astrometry: by detecting the motion of source objects which are not uniform and are observed to ‘wobble’ or otherwise change direction from what would otherwise be expected;

2. photometry: when aligned with Gaia’s line of sight, where one star is observed to pass in front of another and periodically ‘eclipse’ its companion;

3. and spectroscopy: these binaries have a radial velocity that varies periodically, depending on whether a star approaches or recedes from our viewpoint at Earth.

Professor Barstow continued: “We have so much more data on binaries with this release and, crucially, that data is so much more precise than what has gone before.

“Once you have more precise data about a binary system you can work out all sorts of things such as ages and composition: all aspects we haven’t had information on before.

“And by answering those questions, we can start to understand more of the fundamentals about how our Universe works, including how stars live and die.”

‘Gaia Data Release 3: Stellar multiplicity, a teaser for the hidden treasure ’ and ‘Gaia Data Release 3: The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra ’ are among the papers published in the journal Astronomy & Astrophysics.  




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