Skip to main content
  1. Home
  2. Space
  3. News

Exoplanet with eccentric orbit discovered in the habitable zone of a red dwarf

Georgina Torbet
By

Astronomers have found a planet in the habitable zone of a red dwarf star, but its orbit is so elongated that it would have wildly variable temperatures and likely couldn’t support life.

The planet, named TOI-2257 b, was first spotted using data from NASA’s planet-hunting telescope TESS (Transiting Exoplanet Survey Satellite) and then observed in more detail using the Las Cumbres Observatory Global Telescope and the SAINT-EX telescope in Mexico. Using the SAINT-EX observations, the researchers were able to confirm that a planet was orbiting the red dwarf star every 35 days.

The SAINT-EX telescope.
The SAINT-EX telescope Institute of Astronomy, UNAM / E. Cadena

As red dwarf stars are smaller and cooler than our sun, the habitable zone around them, or the area in which liquid water could exist on the surface of an orbiting planet, is also different. Planets orbiting red dwarf stars could have liquid water even if they orbit much closer than the Earth orbits the sun. And having the planet close to the star also makes it easier to detect.

Related

However, even though TOI-2257 b is in the habitable zone, don’t make any plans to move there just yet. The first issue with habitability is that the planet has a radius 2.2 times that of Earth, meaning it is large and likely gaseous with high atmospheric pressure. The second and most intriguing fact about this planet is that it has a highly eccentric orbit, meaning that its orbit traces an elliptical or oval shape rather than a circle. Sometimes the planet is close to its star, and other times it is further away.

Recommended Videos

In fact, it has the most eccentric orbit of a planet around a cool star discovered to date. And that has a big effect on surface temperatures there.

“We found that TOI-2257 b does not have a circular, concentric orbit,” lead researcher Nicole Schanche explained in a statement. “In terms of potential habitability, this is bad news. While the planet’s average temperature is comfortable, it varies from -80°C to about 100°C depending on where in its orbit the planet is, far from or close to the star.”

The researchers are curious as to why the planet’s orbit is so eccentric, which could be due to a giant planet in the same system affecting this planet’s orbit. To learn more, the researchers hope that the planet could be studied further using the James Webb Space Telescope.

Editors' Recommendations

Topics
Georgina Torbet
Georgina Torbet
Space Writer
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
How James Webb peers into the atmospheres of far-off exoplanets
Illustration of a planet on a black background. The planet is large and rocky. Roughly two-thirds of the planet is lit, while the rest is in shadow.

We are entering a new period of exoplanet astronomy, with a recent announcement that the James Webb Space Telescope has detected its first exoplanet. The promise of Webb is that it will be able to not only spot exoplanets but also study their atmospheres, which would mark a major step forward in exoplanet science.

Studying exoplanets is extremely challenging because they are generally far too far away and too small to be observed directly. Very occasionally, a telescope is able to directly image an exoplanet, but most of the time researchers have to infer that a planet is present by looking at the star around which it orbits. There are several methods for detecting planets based on their effects on a star, but one of the most commonly used is the transit method, in which a telescope observes a star and looks for a very small dip in brightness which happens when a planet passes between the star and us. This is the method Webb used to detect its first exoplanet, named LHS 475 b.

Read more
James Webb gets most detailed look yet at an exoplanet’s atmosphere
New observations of WASP-39b with the JWST have provided a clearer picture of the exoplanet, showing the presence of sodium, potassium, water, carbon dioxide, carbon monoxide and sulfur dioxide in the planet's atmosphere. This artist's illustration also displays newly detected patches of clouds scattered across the planet.

One of the big advances promised by the James Webb Space Telescope is the ability to investigate exoplanets in greater detail than ever before. Webb has already imaged its first exoplanet and made the first detection of carbon dioxide in an exoplanet atmosphere, but now astronomers have used the telescope to get the most in-depth look yet at the atmosphere of planet WASP-39 b.

Webb uses instruments called spectrometers which break light down into different wavelengths to see which ones have been absorbed by various molecules in an atmosphere. This allows researchers to see spectra of the planet's atmosphere, telling them what elements are present, which the researchers describe as a "game changer" for the study of exoplanets.

Read more
Strangely chonky exoplanet has astronomers puzzled
Artist’s conception of a gas giant exoplanet orbiting around a Sun-like star. The young exoplanet HD 114082 b revolves around its Sun-like star within 110 days at a distance of 0.5 astronomical units.

Astronomers recently discovered a hefty exoplanet orbiting a star similar to our sun. At just 15 million years old, this chunky planet is a baby by galactic standards, old, but it has researchers puzzled due to its tremendous density.

The planet, called HD 114082 b, is similar in size to Jupiter, but seems to have eight times its mass. It's common for astronomers to discover gas giants similar to or larger than Jupiter, but it's very unusual to discover a planet this dense and heavy.  “Compared to currently accepted models, HD 114082 b is about two to three times too dense for a young gas giant with only 15 million years of age,” said lead author Olga Zakhozhay in a statement.

Read more