A simulated image of NASA’s Nancy Grace Roman Space Telescope’s future observations toward the center of our galaxy, spanning less than 1 percent of the total area of Roman’s Galactic Bulge Time-Domain Survey. The simulated stars were drawn from the Besançon Galactic Model.
Exploring the Changing Universe with the Roman Space Telescope
The view from your backyard might paint the universe as an unchanging realm, where only twinkling stars and nearby objects, like satellites and meteors, stray from the apparent constancy. But stargazing through NASA’s upcoming Nancy Grace Roman Space Telescope will offer a front row seat to a dazzling display of cosmic fireworks sparkling across the sky.
Roman will view extremely faint infrared light, which has longer wavelengths than our eyes can see. Two of the mission’s core observing programs will monitor specific patches of the sky. Stitching the results together like stop-motion animation will create movies that reveal changing objects and fleeting events that would otherwise be hidden from our view.
Watch this video to learn about time-domain astronomy and how time will be a key element in NASA’s Nancy Grace Roman Space Telescope’s galactic bulge survey. Credit: NASA’s Goddard Space Flight Center
This type of science, called time-domain astronomy, is difficult for telescopes that have smaller views of space. Roman’s large field of view will help us see huge swaths of the universe. Instead of always looking at specific things and events astronomers have already identified, Roman will be able to repeatedly observe large areas of the sky to catch phenomena scientists can't predict. Then astronomers can find things no one knew were there!
One of Roman’s main surveys, the Galactic Bulge Time-Domain Survey, will monitor hundreds of millions of stars toward the center of our Milky Way galaxy. Astronomers will see many of the stars appear to flash or flicker over time.
This animation illustrates the concept of gravitational microlensing. When one star in the sky appears to pass nearly in front of another, the light rays of the background source star are bent due to the warped space-time around the foreground star. The closer star is then a virtual magnifying glass, amplifying the brightness of the background source star, so we refer to the foreground star as the lens star. If the lens star harbors a planetary system, then those planets can also act as lenses, each one producing a short change in the brightness of the source. Thus, we discover the presence of each exoplanet, and measure its mass and how far it is from its star. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab
That can happen when something like a star or planet moves in front of a background star from our point of view. Because anything with mass warps the fabric of space-time, light from the distant star bends around the nearer object as it passes by. That makes the nearer object act as a natural magnifying glass, creating a temporary spike in the brightness of the background star’s light. That signal lets astronomers know there’s an intervening object, even if they can’t see it directly.
This artist’s concept shows the region of the Milky Way NASA’s Nancy Grace Roman Space Telescope’s Galactic Bulge Time-Domain Survey will cover – relatively uncharted territory when it comes to planet-finding. That’s important because the way planets form and evolve may be different depending on where in the galaxy they’re located. Our solar system is situated near the outskirts of the Milky Way, about halfway out on one of the galaxy’s spiral arms. A recent Kepler Space Telescope study showed that stars on the fringes of the Milky Way possess fewer of the most common planet types that have been detected so far. Roman will search in the opposite direction, toward the center of the galaxy, and could find differences in that galactic neighborhood, too.
Using this method, called microlensing, Roman will likely set a new record for the farthest-known exoplanet. That would offer a glimpse of a different galactic neighborhood that could be home to worlds quite unlike the more than 5,500 that are currently known. Roman’s microlensing observations will also find starless planets, black holes, neutron stars, and more!
This animation shows a planet crossing in front of, or transiting, its host star and the corresponding light curve astronomers would see. Using this technique, scientists anticipate NASA’s Nancy Grace Roman Space Telescope could find 100,000 new worlds. Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA/GESTAR)
Stars Roman sees may also appear to flicker when a planet crosses in front of, or transits, its host star as it orbits. Roman could find 100,000 planets this way! Small icy objects that haunt the outskirts of our own solar system, known as Kuiper belt objects, may occasionally pass in front of faraway stars Roman sees, too. Astronomers will be able to see how much water the Kuiper belt objects have because the ice absorbs specific wavelengths of infrared light, providing a “fingerprint” of its presence. This will give us a window into our solar system’s early days.
This animation visualizes a type Ia supernova.
Roman’s High Latitude Time-Domain Survey will look beyond our galaxy to hunt for type Ia supernovas. These exploding stars originate from some binary star systems that contain at least one white dwarf – the small, hot core remnant of a Sun-like star. In some cases, the dwarf may siphon material from its companion. This triggers a runaway reaction that ultimately detonates the thief once it reaches a specific point where it has gained so much mass that it becomes unstable.
NASA’s upcoming Nancy Grace Roman Space Telescope will see thousands of exploding stars called supernovae across vast stretches of time and space. Using these observations, astronomers aim to shine a light on several cosmic mysteries, providing a window onto the universe’s distant past. Credit: NASA’s Goddard Space Flight Center
Since these rare explosions each peak at a similar, known intrinsic brightness, astronomers can use them to determine how far away they are by simply measuring how bright they appear. Astronomers will use Roman to study the light of these supernovas to find out how quickly they appear to be moving away from us.
By comparing how fast they’re receding at different distances, scientists can trace cosmic expansion over time. This will help us understand whether and how dark energy – the unexplained pressure thought to speed up the universe’s expansion – has changed throughout the history of the universe.
NASA’s Nancy Grace Roman Space Telescope will survey the same areas of the sky every few days. Researchers will mine this data to identify kilonovas – explosions that happen when two neutron stars or a neutron star and a black hole collide and merge. When these collisions happen, a fraction of the resulting debris is ejected as jets, which move near the speed of light. The remaining debris produces hot, glowing, neutron-rich clouds that forge heavy elements, like gold and platinum. Roman’s extensive data will help astronomers better identify how often these events occur, how much energy they give off, and how near or far they are.
And since this survey will repeatedly observe the same large vista of space, scientists will also see sporadic events like neutron stars colliding and stars being swept into black holes. Roman could even find new types of objects and events that astronomers have never seen before!
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5 Years, 8 Discoveries: NASA Exoplanet Explorer Sees Dancing Stars & a Star-Shredding Black Hole
This all-sky mosaic was constructed from 912 Transiting Exoplanet Survey Satellite (TESS) images. Prominent features include the Milky Way, a glowing arc that represents the bright central plane of our galaxy, and the Large and Small Magellanic Clouds – satellite galaxies of our own located, respectively, 160,000 and 200,000 light-years away. In the northern sky, look for the small, oblong shape of the Andromeda galaxy (M 31), the closest big spiral galaxy, located 2.5 million light-years away. The black regions are areas of sky that TESS didn’t image. Credit: NASA/MIT/TESS and Ethan Kruse (University of Maryland College Park)
On April 18, 2018, we launched the Transiting Exoplanet Survey Satellite, better known as TESS. It was designed to search for planets beyond our solar system – exoplanets – and to discover worlds for our James Webb Space Telescope, which launched three years later, to further explore. TESS images sections of sky, one hemisphere at a time. When we put all the images together, we get a great look at Earth’s sky!
In its five years in space, TESS has discovered 326 planets and more than 4,300 planet candidates. Along the way, the spacecraft has observed a plethora of other objects in space, including watching as a black hole devoured a star and seeing six stars dancing in space. Here are some notable results from TESS so far:
During its first five years in space, our Transiting Exoplanet Survey Satellite has discovered exoplanets and identified worlds that can be further explored by the James Webb Space Telescope. Credit: NASA/JPL-Caltech
1. TESS’ first discovery was a world called Pi Mensae c. It orbits the star Pi Mensae, about 60 light-years away from Earth and visible to the unaided eye in the Southern Hemisphere. This discovery kicked off NASA's new era of planet hunting.
2. Studying planets often helps us learn about stars too! Data from TESS & Spitzer helped scientists detect a planet around the young, flaring star AU Mic, providing a unique way to study how planets form, evolve, and interact with active stars.
Located less than 32 light-years from Earth, AU Microscopii is among the youngest planetary systems ever observed by astronomers, and its star throws vicious temper tantrums. This devilish young system holds planet AU Mic b captive inside a looming disk of ghostly dust and ceaselessly torments it with deadly blasts of X-rays and other radiation, thwarting any chance of life… as we know it! Beware! There is no escaping the stellar fury of this system. The monstrous flares of AU Mic will have you begging for eternal darkness. Credit: NASA/JPL-Caltech
3. In addition to finding exoplanets on its own, TESS serves as a pathfinder for the James Webb Space Telescope. TESS discovered the rocky world LHS 3844 b, but Webb will tell us more about its composition. Our telescopes, much like our scientists, work together.
4. Though TESS may be a planet-hunter, it also helps us study black holes! In 2019, TESS saw a ‘‘tidal disruption event,’’ otherwise known as a black hole shredding a star.
When a star strays too close to a black hole, intense tides break it apart into a stream of gas. The tail of the stream escapes the system, while the rest of it swings back around, surrounding the black hole with a disk of debris. Credit: NASA's Goddard Space Flight Center
5. In 2020, TESS discovered its first Earth-size world in the habitable zone of its star – the distance from a star at which liquid water could exist on a planet’s surface. Earlier this year, a second rocky planet was discovered in the system.
You can see the exoplanets that orbit the star TOI 700 moving within two marked habitable zones, a conservative habitable zone, and an optimistic habitable zone. Planet d orbits within the conservative habitable zone, while planet e moves within an optimistic habitable zone, the range of distances from a star where liquid surface water could be present at some point in a planet’s history. Credit: NASA Goddard Space Flight Center
6. Astronomers used TESS to find a six-star system where all stars undergo eclipses. Three binary pairs orbit each other, and, in turn, the pairs are engaged in an elaborate gravitational dance in a cosmic ballroom 1,900 light-years away in the constellation Eridanus.
7. Thanks to TESS, we learned that Delta Scuti stars pulse to the beat of their own drummer. Most seem to oscillate randomly, but we now know HD 31901 taps out a beat that merges 55 pulsation patterns.
Sound waves bouncing around inside a star cause it to expand and contract, which results in detectable brightness changes. This animation depicts one type of Delta Scuti pulsation — called a radial mode — that is driven by waves (blue arrows) traveling between the star's core and surface. In reality, a star may pulsate in many different modes, creating complicated patterns that enable scientists to learn about its interior. Credit: NASA’s Goddard Space Flight Center
8. Last is a galaxy that flares like clockwork! With TESS and Swift, astronomers identified the most predictably and frequently flaring active galaxy yet. ASASSN-14ko, which is 570 million light-years away, brightens every 114 days!
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