NASA’s Hubble Telescope has precisely measured LTT 1445Ac, an Earth-sized exoplanet in a nearby triple star system. First discovered by TESS, this rocky planet is similar in size to Earth, but much hotter. This research deepens our knowledge of exoplanets and their atmospheres. Credit: ESA/Hubble (M. Kohnmesser & LL Christensen)
Hubble telescope confirms size similar to Earth exoplanet LTT 1445Ac provides new insights into its composition and potential for further atmospheric research.
Many of the planets around nearby stars cannot be seen directly. Instead, they are discovered as they briefly pass in front of their parent star. This is an event called a transit. During their passage, they block some of the light from the star, essentially casting a shadow on Earth observers.
Astronomers learn a lot from these temporary events. They can measure the planet’s orbital period, study its atmosphere, and estimate its size. The complication is that the planet may simply graze the edge of the star during its passage, making measurements of its diameter inaccurate.
One such nearby exoplanet, LTT 1445Ac, is located just 22 light-years away and was the first to be identified. NASATransiting Exoplanet Survey Satellite (Tess). However, TESS lacks the optical resolution needed to refine the orbit across the star’s surface and determine the exact diameter of the planet.
Hubble also came along with its keen vision and accurately measured the diameter of the planet to be only 1.07 times the diameter of Earth. This makes it a cousin of Earth in terms of size. But all similarities end there. LTT 1445Ac is a red dwarf star too close to the Sun to be habitable.Surface temperature is approximately 500 degrees Fahrenheit – Temperature inside the pizza oven.
![Exoplanet LTT 1445Ac](https://scitechdaily.com/images/Exoplanet-LTT-1445Ac-777x437.jpg)
This is an artist’s concept for the nearby exoplanet LTT 1445Ac, which is about the same size as Earth. This planet orbits a red dwarf star. The star is in a triple system, and her two closely orbiting red dwarfs can be seen in the upper right. The black dot in front of the bright pale red sphere in the center of the image is the planet LTT 1445Ac passing through the star’s surface. The planet’s surface temperature is about 500 degrees Fahrenheit. In the lower left of the foreground is another planet in this system, LTT 1445Ab. This view looks back at the Sun, the bright dot in the lower right, from 22 light years away. Some of the stars in the background are part of the constellation Boes. Credit: NASA, ESA, Leah Hustak (STScI)
Hubble Space Telescope measures the size of the closest Earth-sized planet passing by
NASA’s Hubble Space Telescope has measured the size of the closest Earth-sized exoplanet to pass through the surface of a neighboring star. This sequence, called a transit, opens the door to subsequent studies to see what kind of atmosphere exists in the rocky world.
This small planet, LTT 1445Ac, was first discovered in 2022 by NASA’s Transiting Exoplanet Survey Satellite (TESS). However, because TESS lacks the necessary optical resolution, the geometry of the planet’s orbital plane relative to the star as seen from Earth was uncertain. .This is because the detection is called Grazing transport, the planet only skims a small part of its parent star’s disk. This can lead to inaccurate lower bounds on planet diameters.
“This system may have an unlucky shape, in which case we cannot measure its correct size. But using Hubble’s capabilities, we were able to determine its diameter,” said the Center for Astrophysics. Emily Pass said. Harvard University and the Smithsonian Institution in Cambridge, Massachusetts.
Hubble observations show that the planet is making a normal transit that completely traverses the star’s disk, and its actual size is only 1.07 times the diameter of Earth. This means that the planet is a rocky world, similar to Earth, and has approximately the same surface gravity. However, the surface temperature is approximately 500 degrees Fahrenheit, which is too hot for life as we know it.
![Comparison of transit routes](https://scitechdaily.com/images/Comparison-of-Transit-Paths-777x437.jpg)
This diagram compares two scenarios of how an Earth-sized exoplanet could pass in front of its host star. The bottom path shows the planet grazing the star. Studying the light from such transits can inaccurately estimate the planet’s size, making it appear smaller than it really is. The path above shows the optimal geometry for the planet to pass through the entire disk of the star. The Hubble Space Telescope’s precision allows it to distinguish between these two scenarios and accurately measure the planet’s diameter. Credit: NASA, ESA, Elizabeth Wheatley (STScI)
The planet orbits the star LTT 1445A, part of a triple system of three red dwarf stars located 22 light-years away in the constellation Eridanus. This star has two other planets reported to be larger than LTT 1445Ac. Two of his other dwarf stars, a close pair of LTT 1445B and C, are located about 3 billion miles away from LTT 1445A and were also resolved by Hubble. The alignment of the three stars and the side-by-side orbits of the BC pair suggest that everything in this system, including the known planets, is coplanar.
“Transiting planets are interesting because spectroscopy using Hubble as well as the James Webb Space Telescope can reveal atmospheric features. Our measurements suggest that this could be a very nearby terrestrial planet. “It’s important because it shows that it’s very high. We look forward to future observations that will allow us to better understand the diversity of planets around other stars,” Paz said.
This research astronomical journal.
References: “HST/WFC3 Light Curve Supports a Terrestrial Composition for the Closest Exoplanet to Transit an M Dwarf” Emily K. Pass, Jennifer G. Winters, David Charbonneau, Aurelia Balkanski, Nikole Lewis, Maura Lally, Jacob L. Bean, Ryan Cloutier and Jason D. Eastman, September 25, 2023 astronomical journal.
DOI: 10.3847/1538-3881/acf561
of hubble space telescope This is an international cooperation project between NASA and ESA. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, operates Hubble science. STScI is operated for NASA by the Association of Universities for Astronomical Research in Washington, DC.