(ORDO NEWS) — The red dwarf, only 105 light-years away, may have at least one habitable world.
In close orbit around a cold, dim star, scientists have discovered and confirmed the presence of two rocky exoplanets, one of which is quite comfortable. at a great distance from the star, known as the habitable zone.
More observations will be needed to further determine its nature, but the discovery is exciting, suggesting there may be more such worlds. waiting to be discovered in the vicinity of the Sun.
Even if an exoplanet is uninhabitable, worlds in the habitable zone are relatively rare, especially rocky ones.
So, in any case, this discovery is an important data point for characterizing the population of these exoplanets.
These two exoplanets were discovered as a result of observations from NASA’s TESS Exoplanet Search Telescope.
As he looked at a small red dwarf called LP 890-9 (aka TOI-4306) he caught faint, regular dips in starlight that are characteristic of the exoplanet’s orbit. between us and the star, passages known as transits, within 2.7 days.
Transit data can tell us a lot about exoplanets. First, the fact of its existence. Then there is the orbital period. And based on how much starlight dims, scientists can also infer the exoplanet’s diameter.
But to confirm the discovery and get more data on exoplanets, more observations are needed using different instruments.
“This extension,” explains astronomer Laetitia Delres from the University of Liège in Belgium, “is especially important in the case of relatively cool stars like TOI-4306, which emit most of their light in the near infrared, and for which TESS has a rather limited sensitivity.” .
She and her team used telescopes from the SPECULOOS (Search for Habitable Planets That Eclipse Supercool Stars) consortium that are sensitive to near-infrared waves emitted by TOI-4306. Transit data from these observations confirmed the existence of an exoplanet named LP 890-9b.
The team then looked for exoplanets that might have been missed by TESS – and found a second world slightly further from the star than LP 890-9b. The exoplanet, named LP 890-9c, has an orbital period of 8.4 days.
Other data, including radial velocity measurements that determine the gravitational pull of an exoplanet to a star and thus determine their mass, allowed the team to characterize the two exoplanets in detail.
Although the two masses were not measured, the radial velocity data gave scientists an upper mass limit for both exoplanets.
LP 890-9b is about 1.32 times the Earth’s diameter and up to 13 times its mass.
LP 890-9c is about 1.37 times the Earth’s diameter and up to 25 times its mass.
These measurements are consistent with the density of rocky worlds such as Earth, Mars and Venus, rather than gaseous or icy worlds such as Jupiter or Neptune.
This means that exoplanets can be classified as super-Earths. – rocky worlds that are larger than the Earth and smaller than Neptune.
Where they orbit the star – in particular, the outer exoplanet LP 890-9c – it hits. interesting.
This is one of the first things scientists look at when assessing the potential habitability of an alien world. An exoplanet too close or too far from its star will be too hot or too cold, respectively, for life as we know it.
But there is a temperate or habitable zone near the orbit of each star. in which liquid water could comfortably sit on the surface of the planet.
LP 890-9c may be in close orbit to its star compared to Earth, but that star is much, much colder and dimmer than the Sun.
In its orbital position, the exoplanet is within the conservative habitable zone of its star, receiving the same levels of stellar radiation as Earth.
After the TRAPPIST system, it is the second most promising potentially habitable planet. The researchers said that the world has not yet been discovered.
“But we must not get ahead of ourselves. The right location does not guarantee a palm beach,” says astronomer Robert Wells from the University of Bern in Germany.
“Our neighboring planet Venus, which is a carbon dioxide-rich pressure cooker with a temperature of about 500 degrees Celsius, so to speak, is also next to it, which is why it is called the habitable zone around the Sun.”
LP 890-9c is very close to the point where a young planet could be swept up in a runaway greenhouse effect like Venus, but we don’t know for sure what’s going on there.
A second group of scientists, including some of the authors of LP 890-9, have already submitted a preprint exploring this mystery, but we probably won’t know until we get observations of an exoplanet’s atmosphere, if it has one.
The James Webb Space Telescope has already proven effective in this. The telescope, as you understand, is in great demand, so we may have to wait a while with observations.
On the other hand, a target as promising as LP 890-9c may require effort, whatever the outcome, we have a lot to learn.
“It is important,” says astronomer Amory Trio of the University of Birmingham in the UK, “to find as many temperate terrestrial worlds as possible in order to study the diversity of exoplanet climates and, ultimately, be able to measure how often biology appeared in space.”
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