Astrophysicist proposes a new definition of a Planet. At present, there’s confusion regarding whether the biggest planets really are planets.
Kevin Schlaufman, an astrophysicist at Johns Hopkins University, has brought up a new definition in a paper published in the Astrophysical Journal on Monday.
He suggests there’s a better way to define maximum planet size. The astrophysicist also proposes an update to the definition based on how planets form.
“Objects more massive than (around 10 times the mass of Jupiter) should not be thought of as planets,” he writes in the study.
He based his idea on the fact that Jupiter-sized planets seem to prefer stars with a lot of metal, such as our sun. He notes that bigger objects don’t care about how much metal is on the disk. Thus, form from collapsing under their own gravity.
“The maximum mass at which celestial bodies no longer preferentially orbit metal-rich solar-type dwarf stars can, therefore, be used to separate massive planets from brown dwarfs and establish the mass of the largest objects that can be formed through core accretion,” he writes.
His definition will help distinguish between two “suspects:” a giant planet and a celestial object called a brown dwarf. Brown dwarfs are more massive than planets but less massive than the smallest stars.
The astrophysicist calculated a more accurately upper limit of what can be a planet. So, scientists can more accurately narrow their search for exoplanets and avoid mislabeling objects, like brown dwarfs, as planets.
“The official [International Astronomical Union] IAU definition of a ‘planet’ adopted in 2006 is meant to apply only in our Solar System,” Schlaufman, tells Inverse in an email. “There is no official IAU definition of what should be called an ‘exoplanet’ or ‘extrasolar planet’. In 2003, the IAU Working Group on Extrasolar Planets adopted a working definition.”
What’s a planet? A dwarf planet? What about a brown dwarf? Astronomers are struggling in precisely defining these kinds of celestial bodies, and things might change in the years to come.
However, as the astrophysicist, Neil deGrasse Tyson says: “The Universe is under no obligation to make sense to you.” So, there are trillions of trillions of trillions of celestial objects up there and it is our job to name and categorize them.