Starlight study illuminates Earth-like traits of a neighboring rocky exoplanet
A rocky planet with Earth-like temperatures just 11 light years away caused quite a stir when it was discovered last year. Its close proximity and potential to harbor alien life made Ross 128 b a good candidate for further study, and scientists continuing to poke around this pocket of the universe are continuing to unravel its mysteries, with new findings shedding further light on its Earth-like composition.
Ross 128 b was discovered last November by researchers using the European Southern Observatory's High Accuracy Radial Velocity Planet Searcher in Chile. Their immediate conclusions described an Earth-like world orbiting the red dwarf star Ross 128, at around one twentieth of the distance between the Earth and our Sun.
Luckily for Ross 128 b, its parent star is a lot smaller and cooler than our own, which means that despite its tight orbit surface temperatures are estimated to be somewhat hospitable, in the range of -60 to 20 °C (-76 to 68 °F).
Another factor working in favor of possible life forms is that this red dwarf appears to be relatively inactive when it comes to emitting solar flares that can strip nearby planets of their atmospheres, the kind that seriously harm the chances of life on another much-hyped exoplanet, Proxima b.
It is through the characteristics of the red dwarf Ross 128 that scientists continue to learn more about the exoplanet Ross 128. Scientists from Carnegie Mellon University and Brazil's Observatório Nacional turned the Sloan Digital Sky Survey's APOGEE spectroscopic instrument towards the star, and using newly developed techniques, were able to analyze its near-infrared light.
From this, the team was able to deduce the concentrations of chemical elements like carbon, oxygen, magnesium, aluminum, potassium, calcium, titanium and iron in the star. The elements can offer clues about nearby rocky planets, because those bodies are formed from the disks of gas and dust that spin around the parent star in its early years, and the star's chemistry is factor in the makeup of those disks.
So by extension, this chemistry can impact the makeup of the planet's mineralogy, but it doesn't stop there. Because elements like magnesium, iron and silicon in a planet influence the mass ratio of its core and mantle, the star's chemistry can also offer clues as to its interior structure and how Earth-like it might be.
The team's research found that the iron levels of Ross 128 to be similar to that of our Sun, and that its ratio of iron to magnesium suggests that the core of planet Ross 128 b is larger than Earth's. The new findings also enabled the team to estimate the planet's radius which, when combined with estimates of temperature, allowed it to determine how much starlight is reflecting off the surface, another indicator of the climate.
"It's exciting what we can learn about another planet by determining what the light from its host star tells us about the system's chemistry," said Observatório Nacional's Diogo Souto, lead author on the new paper. "Although Ross 128 b is not Earth's twin, and there is still much we don't know about its potential geologic activity, we were able to strengthen the argument that it's a temperate planet that could potentially have liquid water on its surface."
The research was published in The Astrophysical Journal Letters.
Source: Carnegie Mellon University