Hubble measures the size of the closest transiting Earth twin

2023-11-16 18:28:08

MADRID, 16 Nov. (EUROPA PRESS) –

The Hubble Space Telescope has measured the size of the closest Earth-sized exoplanet passing through the face of a neighboring star.

This alignment, called a transit, opens the door to further studies to see what type of atmosphere, if any, could have the rocky world.

The tiny planet, LTT 1445Ac, was first discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) in 2022. But the geometry of the planet’s orbital plane relative to its star as seen from Earth was uncertain because TESS does not have the required optical resolution. This means that the detection could have been a so-called grazing transit, where a planet only grazes a small portion of the parent star’s disk. This would result in an inaccurate lower limit of the planet’s diameter.

“There was a possibility that this system had an unfortunate geometry, and if that were the case, we would not measure the correct size. But with Hubble’s capabilities we were able to determine its diameter,” he said. it’s a statement Emily Pass of the Harvard and Smithsonian Center for Astrophysics.

Hubble observations show that the planet makes a normal transit completely through the star’s disk, yielding an actual size of only 1.07 times the diameter of Earth. This means that the planet is a rocky world, like Earth, with approximately the same surface gravity. But at a surface temperature of about 260 degrees Celsius, It’s too hot for life as we know it.

The planet orbits the star LTT 1445A, which is part of a triple system of three red dwarf stars located 22 light years away, in the constellation Eridanus. The star has two other planets reported to be larger than LTT 1445Ac. A pair of two other dwarf stars, LTT 1445B and C, are located about 5 billion kilometers away from LTT 1445A, also resolved by Hubble. The alignment of the three stars and the edge-on orbit of pair B and C suggests that everything in the system is coplanar, including known planets.

“Transiting planets are interesting because we can characterize their atmospheres using spectroscopy, not only with Hubble but also with the James Webb Space Telescope. Our measurement is important because it tells us that this is probably a very close terrestrial planet. We look forward to follow-up observations will allow us to better understand the diversity of planets around other stars“Pass said.

This research has been accepted for publication in The Astronomical Journal.