Jupiter exoplanet around baby star

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The uncertainty of science: Astronomers have discovered a Jupiter-class exoplanet orbiting a very young star, something their models of planetary formation told them shouldn’t happen.

“For decades, conventional wisdom held that large Jupiter-mass planets take a minimum of 10 million years to form,” said Christopher Johns-Krull, the lead author of a new study about the planet, CI Tau b, that will be published in The Astrophysical Journal. “That’s been called into question over the past decade, and many new ideas have been offered, but the bottom line is that we need to identify a number of newly formed planets around young stars if we hope to fully understand planet formation.”

CI Tau b is at least eight times larger than Jupiter and orbits a 2 million-year-old star about 450 light years from Earth in the constellation Taurus.

In other words, a planet that, according to the present models for planetary formation, supposedly needs 10 million years to form is orbiting a star only 2 million years old. In other words, the models are wrong. We simply don’t know enough yet about planetary formation to create any reliable models.


  • Dick Eagleson

    I’m not sure I see a contradiction here. The “baby star” may have been ignited only 2 million years ago, but it must, itself, have had a lengthy accretion history before reaching a mass required to support ignition. The same is doubtless true of the trans-Jovian exoplanet. In essence, there were two proto-stars in a drag race with each other to see which would ignite first. The “baby star” won this race about 2 million years ago. It’s light pressure and emitted particle flux then either swept away gas which might otherwise have continued to accrete on the exoplanet – in which case the exoplanet will never graduate to, itself, being a star – or the current gas giant exoplanet is still accumulating mass and may someday become the junior part of a binary pair. Binary pairs are common and it seems highly improbable that both stars in a pair typically ignite at precisely the same time. We may just be witnessing half of what will, at some future point, become just another ho-hum, common-as-dirt binary star system and not some allegedly anomalous singularity. My guess is that other systems like this will be found and that the proto-binary pair explanation will apply to many of them as well.

  • Wayne

    Dick Eagleson:
    Very intriguing & well thought out explanation!

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