Astronomers Bear Witness To The First Planet Birth

Astronomers are abuzz over what could be our very first glimpse of a planet being born in the dust surrounding a young star some 350 light-years away from Earth, but don't start passing out cigars just yet.

The star T Chamaeleontis (T Cha) is only a faint dot in the small southern constellation of Chameleon to us, but to astronomers it is a goldmine of information. T Cha is much like our own sun, only younger and sexier. At a mere seven million years old, it's no wonder astronomers like it better. Let's hope the interest holds up now that T Cha might be a parent.

Like many young stars, T Cha is surrounded by a ring of dust known as a protoplanetary disc. It's from this dust that objects like planets, trans-Neptunian objects (stupid Pluto), and other bits of solar system debris are formed. Up until now astronomers haven't been able to study activity in these young dust rings. The Very Large Telescope, powerful array of four optical telescopes located in Chile, has changed all that.

"Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form," notes Johan Olofsson (Max Planck Institute for Astronomy, Heidelberg, Germany), one of the lead authors of two papers in the journal Astronomy & Astrophysics that describe the new work. "But this star is quite distant and the full power of the Very Large Telescope Interferometer (VLTI) was needed to resolve very fine details and see what is going on in the dust disc."

Astronomers first viewed T Cha using the AMBER instrument (Astronomical Multi-BEam combineR), which combines the light from all four telescopes into one cohesive image. That's when they noticed the gap. There's an inner dust ring some 20 million kilometers from the star, followed by a gap, which is in turn followed by the majority of the dust disk, stretching some 1.1 billion kilometers from the star. Mind the gap, it might be a planet.

Nuria Huélamo (Centro de Astrobiología, ESAC, Spain), the lead author of the second paper takes up the story: "For us the gap in the dust disc around T Cha was a smoking gun, and we asked ourselves: could we be witnessing a companion digging a gap inside its protoplanetary disc?"

From there astronomers tacked on a special NACO adaptive optics instrument to the European Southern Observatory's Very Large Telescope, allowing very dim objects to be seen more clearly alongside very bright objects. Analysis of the new imagery discovered the signature of an object much smaller than T Cha itself one billion kilometers from the star - about the same distance as Jupiter sits from our sun.

Astronomers still need to determine if the object is a brown dwarf star (boring) or an actual planet (hooray!), but either way this is an exciting moment for space science.

Huélamo concludes: "This is a remarkable joint study that combines two different state-of-the-art instruments at ESO's Paranal Observatory. Future observations will allow us to find out more about the companion and the disc, and also understand what fuels the inner dusty disc."

Planet Formation in Action? [European Southern Observatory]


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