Now in its fifth year in space, NASA TESS (Transiting Exoplanet Survey Satellite) continues to be a resounding success. TESS cameras have mapped more than 93% of the entire sky, discovered 329 new worlds and thousands more candidatesand provided new insights into a wide range of cosmic phenomena, from stellar pulsations and exploding stars to supermassive black holes.
Using its four cameras, TESS monitors large swaths of the sky called sectors for about a month at a time. Each sector measures 24 by 96 degrees, about the width of a person's hand at arm's length, and extends from the horizon to the zenith. The cameras capture a total of 192 million pixels in each full frame image. During its primary mission, TESS captured one of these images every 30 minutes, but this torrent of data has increased over time. Cameras now record each sector every 200 seconds.
"The volume of high-quality TESS data now available is quite impressive," said Knicole Colón, project scientist for the mission at NASA Goddard Space Flight Center in Greenbelt, Maryland. “We have over 251 terabytes just for one major data product, called full-frame images. That's the equivalent of streaming 167,000 movies in Full HD."
"TESS extracts parts of each full-frame image to clip around specific cosmic objects (more than 467,000 at this time) and together they create a detailed record of each one's brightness changes," said Christina Hedges, TESS Director. . Office of the Investigator General and scientific investigator both in the University of Maryland, Baltimore County and Godard. "We use these files to produce light curves, a product that graphically shows how the brightness of a source alters over time."
To find exoplanets, or worlds beyond our solar system, TESS looks for the telltale dimming of a star that occurs when an orbiting planet passes in front of it. But stars also change brightness for other reasons: exploding like supernovaeerupting in sudden eruptions, dark star spots on their rotating surfaces, and even slight changes due to oscillations driven by internal sound waves. TESS's rapid and regular observations allow for a more detailed study of these phenomena.
Some stars give TESS a trifecta of brightness-changing behavior. An example is AU Microscopii, thought to be about 25 million years old, a young rogue less than 1% the age of our Sun. Spotted regions on the surface of AU Mic grow and shrink, and the rotation of the star carries them in and out of sight. The stormy star also erupts with frequent flares. With all this going on, TESS, with the help of the now retired NASA Spitzer Space Telescope, discovered a planet about four times the size of Earth orbiting the star every 8.5 days. Then, in 2022, scientists announced that TESS data revealed the presence of another, smaller world, one nearly three times the size of Earth and orbiting every 18.9 days. These discoveries have made the system a touchstone for understanding how stars and planets form and evolve.
Here are some more of the greatest mission successes:
- TESS has observed hundreds of supernovae and thousands of other short-lived or transient candidate events so far.
- TOI 700 d was the first planet TESS found to orbit within its star's habitable zone. That is the range of orbital distances where liquid water could potentially exist on the planet's surface. In January, astronomers announced this The Earth-sized world joined another, TOI 700 e, which also orbits in the habitable zone or "Goldilocks" of the star.
- The active galaxy ESO 253-3 hosts a 78 million solar mass black hole that flares up every 114 days, the first supermassive black hole shown to flare regularly. To understand why, the astronomers combined ground-based observations of the flares with data from NASA's TESS. Fast and nuSTAR telescopes and the XMM-Newton satellite operated by ESA (European Space Agency). The most likely answer, they say, is that a giant star passes close enough to the monstrous black hole once in each orbit that the black hole's gravity removes some stellar gas. This material falls inward, creating a flare when it hits the vast disk of gas surrounding the black hole.
- TESS discovered a trio of hot worlds larger than Earth orbiting a much younger version of our Sun called TOI 451, located about 400 light-years away. The system was found in a newly discovered "river" of stars called the Piscis-Eridanus stream, which stretches across a third of the sky. TESS showed that many of the revealed stars had starspots and rotated rapidly. – clear evidence that the stream was only 120 million years old, or one-eighth of the age of previous estimates.
New discoveries are expected within the enormous volume of data that TESS has already captured. This is a library of observations that astronomers will explore for years to come, but there is much more to come.
“We are celebrating the fifth anniversary of TESS at work, and we wish you the best of luck!” Columbus said.
TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Falls Church, Va.-based Northrop Grumman; the NASA Ames Research Center in Silicon Valley in California; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; the MIT Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories around the world are participating in the mission.
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