Young exoplanet found nestled close to its star

Scientists have found one of the youngest exoplanets ever, huddling close to a star that is just 2 million years old. Located 450 light-years from Earth in the constellation Taurus, the star is so young that it still has its baby fat — it is surrounded by the disk of gas and dust from which it formed.

The planet, CI Tau b, is hefty for an infant —  tipping the scales at 11 times the mass of Jupiter, say astronomer Christopher Johns-Krull of Rice University in Houston and colleagues in a paper posted May 25 on arXiv.org. It’s surprising, the researchers say, that such a large planet could have formed in just 2 million years — peanuts on cosmic timescales.

Such baby-faced exoplanets have been spotted before (SN: 12/26/15, p. 14), but they’ve lingered farther from their stars. This fledgling planet shows that such behemoths can form quickly and snuggle close to their stars. Scientists still don’t know whether star-hugging planets form far away and migrate inwards, or whether they are birthed close to their stars. The new planet could shed light on that process.

The scientists used a variety of optical and infrared telescopes to reveal periodic variations in the frequency of the star’s light, caused by the planet’s gravitational pull. CI Tau b tugs its star back and forth as it swings around in a tight orbit that it completes every nine days, the researchers determined. Hints of the planet showed up in both optical and infrared light, ruling out spurious signals caused by sunspots or other variability within the young and active star.

Editor’s note: Science News astronomy writer Christopher Crockett is a coauthor on the paper, which incorporates work he did as an astronomer at Lowell Observatory in Flagstaff, Ariz., prior to joining Science News.