Neil deGrasse Tyson may have helped DC Comics in the search for Superman’s homeworld Krypton, but one can’t help but wonder what kind of superhero would live on a newly discovered “super-Jupiter” orbiting the star Kappa Andromedae.
As announced by scientists using the High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) and the Infrared Camera and Spectrograph (IRCS) mounted on the Japanese Subaru Telescope atop Mauna Kea, Hawaii, this newly discovered exoplanet is likely a little exotic. Weighing-in at a whopping 13 Jupiter masses, there is some ambiguity as to whether it’s a massive planet or a small, failed star — although spectroscopic analysis of the light it generates suggests it is composed of similar gases as other gas giant exoplanets orbiting other stars.
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Failed stars, commonly known as brown dwarfs, are the runts of the stellar litter. They may be big, but they’re not big enough to sustain nuclear fusion in their cores. A star can’t shine without fusion, so these celestial oddballs are often considered to be the “bridge” between planets and stars.
But that’s not to say that brown dwarfs don’t shine their own special kind of light.
During formation, heat is trapped inside the body of brown dwarfs and released as infrared radiation. Larger brown dwarfs may even generate heat from low levels of deuterium fusion in their cores. Therefore, infrared-sensitive instruments like Subaru’s IRCS are needed to directly image them.
Kappa Andromedae — located in the constellation of Andromeda, some 170 light-years away — is also an interesting star. It is 2.5 times the mass of our sun and is very bright and young. Astronomers estimate Kappa Andromedae at only 30 million years old (the sun is geriatric in comparison — 5 billion years old). This means that Kappa Andromedae b (as the exoplanet is called) is also very young.
Some theories suggest that stars that are young and massive, like Kappa Andromedae, are unlikely to produce planets from their protoplanetary disks (the disks of dusty material that form around young stars). But the very existence of Kappa Andromedae b in an orbit a little larger than the solar system’s Neptune makes this the largest planetary body in orbit around such a massive star to be directly imaged.
Whether the world is big enough to be considered to be a massive exoplanet or brown dwarf, it appears that it was spawned from the protoplanetary disk of Kappa Andromedae, making exoplanetary formation theories even more complex as they are fascinating.
As per the National Astronomical Observatory of Japan (NAOJ) press release:
In recent years some observers and theoreticians have argued that large stars like Kappa Andromedae are likely to have large planets, perhaps conforming to a simple scaled-up model of our own solar system. Other experts suggest that there are limits to extrapolating from our own solar system; if a star is too massive, its powerful radiation may disrupt the “normal” planet formation process that would otherwise occur in the disk surrounding a star, its circumstellar disk. The discovery of the super-Jupiter around Kappa Andromedae demonstrates that stars as large as 2.5 solar masses are still fully capable of producing planets within their circumstellar disks.
As for which superhero might live on Kappa Andromedae, he or she would need to have a high heat tolerance, would have to live in a plasma-like state and enjoy being crushed under intense gravity. But they would also be a little confused as to whether their homeworld is a massive planet, or dinky star. I, for one, would rather live on Krypton.
Image: A false-color, near-infrared (1.2 – 2.4 microns) image of the Kappa Andromedae system. The colored speckles represent starlight left over after removal of light from the host star. Credit: NAOJ