NASA Planet Hunter Finds Earth-Size Habitable-Zone World (Photo Credit: NASA's Goddard Space Flight Center)
Using Transiting Exoplanet Survey Satellite (TESS), the National Aeronautics and Space Administration (NASA) has discovered an Earth-sized, habitable planet orbiting around a star in the range of distances where conditions could allow for the presence of liquid water on the planet’s surface.
According to a statement of NASA, scientists confirmed the find, called TOI 700 d, using NASA's Spitzer Space Telescope. NASA further stated that TOI 700 d is one of only a few Earth-size planets discovered in a star's habitable zone so far. “Others include several planets in the TRAPPIST-1 system and other worlds discovered by NASA's Kepler Space Telescope,” NASA added.
The US Space agency further said, “TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It's roughly 40 per cent of the Sun's mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission's first year, and scientists caught multiple transits by its three planets.”
“The star was originally misclassified in the TESS database as being more similar to our Sun, which meant the planets appeared larger and hotter than they really are. Several researchers, including Alton Spencer, a high school student working with members of the TESS team, identified the error,” it added.
"When we corrected the star's parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone," said Emily Gilbert, a graduate student at the University of Chicago.
"Additionally, in 11 months of data we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions," she added.
The modeling work was funded through the Sellers Exoplanet Environments Collaboration at Goddard, a multidisciplinary collaboration that brings together experts to build comprehensive and sophisticated computer models to better analyze current and future exoplanet observations. In the meantime, astrophysics division director at NASA Headquarters Paul Hertz said, “TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars.”
“Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet’s size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January,” he added.
It is worth mentioning here that the TESS satellite monitors sectors of the sky for 27 days at a time, allowing the satellite to track changes in the brightness of a star caused by an orbiting planet crossing in front of it.