Tour: NASA Finds Young Stars Dim in X-rays Surprisingly Quickly
(Credit: NASA/CXC/A. Hobart)
[Runtime: 03:16]

With closed-captions (at YouTube)

Scientists have found that young stellar cousins of our Sun are calming down and dimming in their X-ray output more quickly than previously thought, according to a new study using NASA’s Chandra X-ray Observatory.

Unlike in the new movie “Project Hail Mary,” this quieting of young stars is a benefit for the prospects for life on orbiting planets around these stars — not a threat.

Astronomers used Chandra and other telescopes to monitor how powerful radiation from young stars — often in the form of dangerous X-rays — can pummel planets surrounding them. They did not know, however, how long this high-energy barrage continued.

This latest study looked at eight clusters of stars between the ages of 45 million and 750 million years old. The researchers found that Sun-like stars older than about 100 million years in these clusters unleashed only about a quarter to a third of the X-rays they expected. For context, our Sun is about 4.6 billion years old, so significantly older than the stellar cousins in this study.

While science fiction — like the microbes in Project Hail Mary — imagines alien life that dims stellar output by consuming its energy, these real observations reveal a natural ‘quieting’ of young Sun-like stars in X-rays. The researchers found this real-life quieting is not from outside force is consuming their light, but because the generation of magnetic fields inside the stars becomes less efficient.

In fact, this calming could be a boon to the formation of life on planets around stars that are younger versions of our own Sun. This is because large amounts of X-rays can erode a planet’s atmosphere and prevent formation of molecules necessary for organic life as we know it. On average, three million year old stars with a mass equal to the Sun produce about a thousand times more X-rays than today's Sun. Meanwhile, 100 million year old solar-mass stars are about 40 times brighter in X-rays than the present Sun.

The scientists in this new study suggest it’s possible that humans owe our existence to our Sun quieting down several billion years ago. This real-world dimming echoes the dramatic stellar change in fiction, but it may be even more fascinating because it highlights our own Sun's actual history.

We can only see our Sun at this current snapshot in time, so to really understand its past we must look to other stars with about the same mass. By studying X-rays from stars that are hundreds of millions of years old, we have filled in a large gap in our understanding of their evolution.

As described in our latest press release, this result has implications for the prospects of life developing and surviving on planets in orbit around these stars.

Trumpler 3 and NGC 2353 are so-called open clusters that contains hundreds of young stars. These stars are tied to each other through gravity, having been formed from the same clouds of gas. Many of these stars have masses that are similar to our Sun, but are much younger. In these new composite images of Trumpler 3 and NGC 2353, X-rays from Chandra (purple) have been combined with an optical image from the PanSTARRS telescope in Hawaii (red, green, and blue). Another star clusters from the new Chandra study, NGC 2301 is shown in the same color schemes with the X-ray and optical data.

Quick Look: NASA Finds Young Stars Dim in X-rays Surprisingly Quickly
(Credit: NASA/CXC/A. Hobart)
[Runtime: 00:46]

With narration (video above with voiceover)

Younger versions of the Sun are quieter and dimmer than scientists thought.

This new study has a parallel to the new “Project Hail Mary” book and movie.

Unlike in the fictional story, this natural dimming likely helps life thrive on planets.

This study from NASA’s Chandra fills in an important gap in our own Sun’s history.