Infant Gas Giant Exoplanet Weighed By ESA’s GAIA For The First Time


Data from the ESA’s GAIA missions, the European Space Agency’s star-mapping spacecraft, and the retired Hipparcos satellite helped scientists weigh an infant gas giant planet for the first time. The planet, called Beta Pictoris b and found in 2008 by the Very Large Telescope at the European Southern Observatory in Chile, is a Super-Jupiter.

Beta Pictoris b, which is about 13 times more massive than Jupiter, and its host star are approximately 20 million years old, meaning they are 225 times younger than our Solar System.

“In the Beta Pictoris system, the planet has essentially just formed. Therefore we can get a picture of how planets form and how they behave in the early stages of their evolution. On the other hand, the star is very hot, rotates fast, and it pulsates,” explained Ignas Snellen, a researcher from the Leiden University, the Netherlands.

To measure its mass, astronomers needed to study the infant gas giant exoplanet’s influence on the trajectory of its host star. To achieve that, observing the star’s trajectory deviations on the long-term was needed.

ESA astronomers weighed an infant gas giant exoplanet for the first time, helped by data from GAIA and Hipparcos

“We are looking at the deviation from what you expect if there was no planet and then we measure the mass of the planet from the significance of this deviation. The more massive the planet, the more significant the deviation,” explained Anthony Brown, also from the Leiden University.

The ESA’s GAIA mission, which has the purpose of observing more than one billion stars in the Milky Way, recorded the Beta Pictoris star for approximately thirty times. However, that was not enough, so the astronomers had to combine the new observations with those of the retired Hipparcos satellite which recorded Beta Pictoris for 111 times between 1990 and 1993.

“By combining data from Hipparcos and Gaia, which have a time difference of about 25 years, you get a very long term proper motion. Now, by combining Gaia and Hipparcos and looking at the difference in the long term and the short term proper motion, we can see the effect of the planet on the star,” said Anthony Brown.


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