Does a nearby star host an Earth-like planet?
The European Southern Observatory's (ESO) Atacama Large Millimeter/submillimeter Array (ALMA) has made some stunning and insightful observations since its inauguration in 2013, including looks at galaxy formation in the early Universe and snaps of the Milky Way's largest known stellar womb. The telescope's latest effort is one of its most impressive yet, providing us with the best-ever look at a planet-forming disc.
TW Hydrae is a particularly interesting target for study, as it's the closest known protoplanetary disc to Earth, meaning that it provides one of our best opportunities to get a good look at how planets form. Located some 175 light-years away, the infant star is just 10 million years old and has a face-on orientation, meaning we can clearly view the structure from Earth.
Previous studies of the star confirmed the presence of the planet-forming disc, but the new imagery from ALMA provides a much closer look, revealing the presence of gaps in the material that strongly indicate the presence of infant planets, formed as particles came together and swept through the expanse of dust and gas.
The data was gathered by looking at radio emissions from the tiny, millimeter-sized particles of dust in the disc. The project was possible thanks to wide separation of ALMA's dishes, which are as much as 15 km (9.3 miles) apart, providing extremely high spatial resolution.
The most intriguing of the gaps in the disc was found at a similar distance to that of the Earth from the Sun – some 150 million km (93 million miles) – indicating that the planet that formed it could have some properties similar to Earth. Other notable gaps in the disc are located three and six billion kilometers from the star, putting the presumed planets in orbits similar to Uranus and Pluto.
Broadly speaking, the findings indicate that TW Hydrae could be fairly similar to our own solar system, only in an infant state. Studying it in greater detail could well reveal new secrets about how planets like Earth form. Looking forward, the researchers plan to scour the night sky for similar planet-forming discs, looking to determine how common the features found around TW Hydrae are, and how they develop over time, and are affected by different conditions.
The new observations aren't the first time that ALMA has turned its gaze towards the mysteries of planet formation. Back in 2015, it helped astronomers spot the fingerprints of huge planets sweeping through the clouds of dust and gas surrounding young stars.
The research was published in the Astrophysical Journal Letters.