The chances of finding extraterrestrial life have improved slightly after NASA announced that its Hubble Space Telescope has confirmed the size of an Earth-sized exoplanet only 22 light-years from Earth, the nearest that passes in front of its star.
Located in the constellation of Eridanus, the exoplanet LTT 1445Ac didn't seem much to write home about. It orbits LTT 1445A, which is one of the three red dwarf stars that make up the triple system of LTT 1445. When it was first discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) in 2022, it was just another of thousands of exoplanets that have become so common in recent years that their discovery long ago went from sensational to routine.
Then the question arose as to exactly how big LTT 1445Ac really is. Such planets are usually discovered when they transit their parent star – that is, they pass in front of the star. As they do so, they cause the light from the star to dip. If this happens often enough, astronomers can not only confirm the presence of the exoplanet, they can also deduce its orbit and size as well as other properties.
In the case of LTT 1445Ac, they had a bit of a problem. If it passed cleanly in front of its star, then it might be about the size of the Earth, which is intensely interesting to scientists because it's so close to us. On the other hand, if the planet only grazes the disc of the star, it could be the size of a super Jupiter because only part of the planet would obstruct the disc.
The aggravating thing was that TESS couldn't resolve this dilemma due to it not having a high enough resolution. To remedy this, scientists turned to NASA's Hubble Space Telescope, which may be almost 30 years older than TESS, but has much higher resolution.
By analyzing the Hubble data, the researchers were able to determine that LTT 1445Ac did make a clean transit of its star and is only 1.07 times the size of the Earth. That may seem like a close match, but don't pack your bags just yet. The surface temperature is about 500 °F (260 °C).
The good news is that since LTT 1445Ac is so close to us, it may be possible to learn more about its atmosphere, which could provide useful information for the search for life.
"Transiting planets are exciting since we can characterize their atmospheres with spectroscopy, not only with Hubble but also with the James Webb Space Telescope," said Emily Pass of the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts. "Our measurement is important because it tells us that this is likely a very nearby terrestrial planet. We are looking forward to follow-on observations that will allow us to better understand the diversity of planets around other stars."
The research will be published in The Astronomical Journal.
Source: NASA
