A look at the Beta Pictoris system with the 3.6 meter telescope of the European Southern Observatory and the NACO instrument on ESO's 8.2 meter Very Large Telescope, the hosts the youngest ever-weighed exoplanet. The planet, Beta Pictoris b, is 226 times younger than the solar system at 20 million years old
Credit: ESO / A-M. Lagrange et al.
Astronomers have measured the mass of a very young alien planet for the first time, thanks to more than two decades of data collected from two European Space Agency star-mapping satellites.
The exoplanet ̵
As this star is still very young, it shows how planets evolve and develop. However, as the star still forms and pulsates with activity, it is a challenge for astronomers to accurately measure the radial velocity of the star (velocity as the star moves toward and away from the earth). This is a method commonly used to estimate the mass of exoplanets. [Beta Pictoris b in Pictures: An Alien Planet Image Gallery]
Instead, the weight of Beta Pictoris b was calculated based on the position and motion of its star in the sky over a long period of time, according to a statement by ESA.
"The star is moving for several reasons," said Ignas Snellen, lead author of the study and astronomer from Leiden University, Netherlands, in the statement. "First, the star revolves around the center of the Milky Way, just like the Sun, which appears from Earth as a linear motion projected onto the sky, we call it self-motion, and then there's the parallax effect, that's We See That Star during the year from different angles. "
"tiny wobble" in the motion of the star, meaning that the star deviates from its expected course due to the gravitational force of Beta Pictoris b, the statement says.
"We look at the deviation from what you expect [would] when there is no planet, and then we measure the mass of the planet from the importance of this deviation," Anthony Brown, co-author of the study and researcher of Leiden University in the Netherlands, said in the statement. "The more massive the planet is, the more significant the deviation is."
However, to accurately estimate the mass of Beta Pictoris b, researchers had to gather observations over a long period of time. This required the combination of Gaia spacecraft data (launched in 2013) and ESA's Hipparcos satellite, which investigated Beta Pictoris 111 times between 1990 and 1993. The measurements of the two space probes showed that the exoplanet infant is nine to thirteen times more massive Jupiter, according to the statement.
"By combining data from Hipparcos and Gaia, which have a time difference of about 25 years, you get a very long-term self-motion," said Brown. "Hipparcos alone would not have been able to find this planet because it would look like a normal single star if we had not measured it much longer."
The results were published on August 20 in the journal Nature Astronomy.