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This Young Star Is a Window Into the Sun’s Past

Astronomers glimpse the innermost region of a developing star.
Concept drawing of planet forming around HD 100546. Image: ESO/L. Calçada

For the first time ever, astronomers have glimpsed the innermost parts of a solar system in its earliest stages of formation. The results, published this week in the Monthly Notices of the Royal Astronomical Society, reveal the interactions between an embryonic star called HD 100546 and a fledgling planet forming in its protoplanetary disk.

This system is fascinating on its own merits, but it also happens to be a great analogue for studying the origins of our solar system. At the tender age of only ten million, HD 100546 is about 1,000 times younger than the Sun, but scientists expect that it will eventually evolve into a Sun-like star. In this way, HD 100546 provides astronomers with an opportunity to watch the mechanisms of solar system formation unfold, which in turn sheds light on how our cosmic neighborhood may have appeared some 4.5 billion years ago.

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"With our observations of the inner disk of gas in the HD 100546 system, we are beginning to understand the earliest life of planet-hosting stars on a scale that is comparable to our solar system," said study co-author Rene Oudmaijer in a statement.

Concept drawing of HD 100546 system. Image: David Cabezas Jimeno/SEA

Oudmaijer and his colleagues were able to study the HD 100546 system in detail using the Very Large Telescope Interferometer (VLTI) instrument in Chile. The facility can achieve incredibly sharp images by combining the resolution of eight separate telescopes. This kind of sensitivity was exactly what the team needed in order to peer deeply into the so-called "amniotic sac" of star and planet formation represented by the HD 100546 system.

"Considering the large distance that separates us from the star (325 light-years), the challenge was similar to trying to observe something the size of a pinhead from 100 kilometers away," said Oudmaijer.

The data captured by the VLTI not only confirmed that HD 100546 has a large planet forming in its inner reaches, it also detected new details about the warped circumstellar disk of gas and dust surrounding the young star. Incredibly, this disk extends around the burgeoning system at a distance equivalent to about ten times the distance between the Sun and Pluto.

Sophisticated new telescopes and instruments like the VLTI have brought the mysteries of solar system formation into sharper focus than ever before. By studying rare young stars like HD 100546, astronomers are not only unlocking the mysteries of alien systems, they are contextualizing the origins of our own.