Only 22 light-years away, and orbiting a small red dwarf star, a team of astronomers was able to measure a nearby world, using the Hubble Space Telescope, that has already been observed in 2022. The result is that it is the same size as Earth. It’s called LTT 1445 Ac, its diameter is practically the same as Earth’s (1.07 times), and it’s the closest known exoplanet with a size similar to our universe. The data was published in a recent article by “Astronomical Journal”.
However, the similarities end there, because the LTT 1445 Ac is too hot to support life. However, its mere presence near us makes it an ideal candidate for learning what makes a planet similar to our own evolve so differently.
It was discovered a year ago
NASA discovered the small world in 2022 thanks to the TESS satellite, but the limited accuracy of its instruments did not allow astronomers to confirm its properties. This is now possible thanks to Hubble’s capabilities. The exoplanet also orbits a star (LTT 1445A) and is part of a “triple” system, meaning it consists of three stars orbiting each other, which is very unusual.
Typically, astronomers search for planets by measuring the precise dimming of the host star’s brightness that occurs when a planet passes in front of it. This is known as the “crossover method.” But in binary systems (made up of two stars) or triples, as the case may be, stars also affect the light of their companions, which can confuse scientists.
So, even though LTT 1445 Ac is only 22 light-years away, it is difficult for astronomers to know the details of what they are seeing. Unless the instruments they use have extraordinary capabilities, as is the case with Hubble.
A world “almost” like ours
In fact, observations made with the veteran telescope have paid off, showing that the planet is making a regular transit around the star and is only 1.07 times the size of Earth. Which means it’s a rocky world, like ours, and has the same surface gravity.
But the difference lies in the temperature, which is about 260 degrees Celsius. It is too hot for life as we know it to develop. However, just being able to find data from LTT 1445 Ac means astronomers will now have an excellent opportunity to study its atmosphere as well, which will help understand how Earth-like worlds form and evolve in the future. Systems with such different architectures.
“Transiting planets – says Emily Bass, from the Harvard-Smithsonian Center for Astrophysics and lead author of the article – are interesting because we can describe their atmospheres using spectroscopy, not only with Hubble but also with the James Webb Space Telescope. Our measurements are important because they tell us that they are likely “We hope to make subsequent observations that will allow us to better understand the diversity of planets around other stars.”
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