A young planet whirling closely around a red dwarf star is changing in unpredictable ways
with each orbit.
NASA’s Hubble Space Telescope observations initially showed the planet wasn’t losing
its atmosphere to its parent star.
One and a half years later, Hubble observations revealed clear signs that the star’s torrential
blasts of energy, called a stellar wind, were stripping the planet’s hydrogen atmosphere.
These extreme changes between orbits, and over such a short period of time, shocked
astronomers.
Red dwarfs are the most abundant stars in our Milky Way galaxy, and they likely host
most of our galaxy’s planets, but can these planets be hospitable to life?
These new Hubble results suggest that this particular red dwarf may have sudden and extremely
variable outbursts.
Under these intense conditions, planets forming within the first 100 million years of the
red dwarf star’s birth should experience the greatest loss of their atmosphere, possibly
stripping it away completely.
One possible explanation for the vastly different Hubble observations is that the torrential
stellar wind shapes the planet’s atmospheric loss, sometimes making it observable and at
other times not.
It may even cause some of the outflow to “hiccup” out ahead of the planet itself.
Stellar models predict this hiccup, but Hubble provided the first observational evidence
of it happening and to an extreme degree.
Thanks to Hubble, we’re learning more about how planets form and survive around stars
very different from our own, helping us uncover the mysteries of the universe.
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