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Superflares From Young Red Dwarf Stars Imperil Planets
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Hubble Space Telescope Home NASA’s Hubble Finds… Hubble Space Telescope Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts E-books Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More Online Activities 5 Min Read NASA’s Hubble Finds Sizzling Details About Young Star FU Orionis
An artist’s concept of the early stages of the young star FU Orionis (FU Ori) outburst, surrounded by a disk of material. Credits:
NASA-JPL, Caltech In 1936, astronomers saw a puzzling event in the constellation Orion: the young star FU Orionis (FU Ori) became a hundred times brighter in a matter of months. At its peak, FU Ori was intrinsically 100 times brighter than our Sun. Unlike an exploding star though, it has declined in luminosity only languidly since then.
Now, a team of astronomers has wielded NASA’s Hubble Space Telescope‘s ultraviolet capabilities to learn more about the interaction between FU Ori’s stellar surface and the accretion disk that has been dumping gas onto the growing star for nearly 90 years. They find that the inner disk touching the star is extraordinarily hot — which challenges conventional wisdom.
The observations were made with the telescope’s COS (Cosmic Origins Spectrograph) and STIS (Space Telescope Imaging Spectrograph) instruments. The data includes the first far-ultraviolet and new near-ultraviolet spectra of FU Ori.
“We were hoping to validate the hottest part of the accretion disk model, to determine its maximum temperature, by measuring closer to the inner edge of the accretion disk than ever before,” said Lynne Hillenbrand of Caltech in Pasadena, California, and a co-author of the paper. “I think there was some hope that we would see something extra, like the interface between the star and its disk, but we were certainly not expecting it. The fact we saw so much extra — it was much brighter in the ultraviolet than we predicted — that was the big surprise.”
A Better Understanding of Stellar Accretion
Originally deemed to be a unique case among stars, FU Ori exemplifies a class of young, eruptive stars that undergo dramatic changes in brightness. These objects are a subset of classical T Tauri stars, which are newly forming stars that are building up by accreting material from their disk and the surrounding nebula. In classical T Tauri stars, the disk does not touch the star directly because it is restricted by the outward pressure of the star’s magnetic field.
The accretion disks around FU Ori objects, however, are susceptible to instabilities due to their enormous mass relative to the central star, interactions with a binary companion, or infalling material. Such instability means the mass accretion rate can change dramatically. The increased pace disrupts the delicate balance between the stellar magnetic field and the inner edge of the disk, leading to material moving closer in and eventually touching the star’s surface.
This is an artist’s concept of the early stages of the young star FU Orionis (FU Ori) outburst, surrounded by a disk of material. A team of astronomers has used the Hubble Space Telescope’s ultraviolet capabilities to learn more about the interaction between FU Ori’s stellar surface and the accretion disk that has been dumping gas onto the growing star for nearly 90 years. They found that the inner disk, touching the star, is much hotter than expected—16,000 kelvins—nearly three times our Sun’s surface temperature. That sizzling temperature is nearly twice as hot as previously believed. NASA-JPL, Caltech
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The enhanced infall rate and proximity of the accretion disk to the star make FU Ori objects much brighter than a typical T Tauri star. In fact, during an outburst, the star itself is outshined by the disk. Furthermore, the disk material is orbiting rapidly as it approaches the star, much faster than the rotation rate of the stellar surface. This means that there should be a region where the disk impacts the star and the material slows down and heats up significantly.
“The Hubble data indicates a much hotter impact region than models have previously predicted,” said Adolfo Carvalho of Caltech and lead author of the study. “In FU Ori, the temperature is 16,000 kelvins [nearly three times our Sun’s surface temperature]. That sizzling temperature is almost twice the amount prior models have calculated. It challenges and encourages us to think of how such a jump in temperature can be explained.”
To address the significant difference in temperature between past models and the recent Hubble observations, the team offers a revised interpretation of the geometry within FU Ori’s inner region: The accretion disk’s material approaches the star and once it reaches the stellar surface, a hot shock is produced, which emits a lot of ultraviolet light.
Planet Survival Around FU Ori
Understanding the mechanisms of FU Ori’s rapid accretion process relates more broadly to ideas of planet formation and survival.
“Our revised model based on the Hubble data is not strictly bad news for planet evolution, it’s sort of a mixed bag,” explained Carvalho. “If the planet is far out in the disk as it’s forming, outbursts from an FU Ori object should influence what kind of chemicals the planet will ultimately inherit. But if a forming planet is very close to the star, then it’s a slightly different story. Within a couple outbursts, any planets that are forming very close to the star can rapidly move inward and eventually merge with it. You could lose, or at least completely fry, rocky planets forming close to such a star.”
Additional work with the Hubble UV observations is in progress. The team is carefully analyzing the various spectral emission lines from multiple elements present in the COS spectrum. This should provide further clues on FU Ori’s environment, such as the kinematics of inflowing and outflowing gas within the inner region.
“A lot of these young stars are spectroscopically very rich at far ultraviolet wavelengths,” reflected Hillenbrand. “A combination of Hubble, its size and wavelength coverage, as well as FU Ori’s fortunate circumstances, let us see further down into the engine of this fascinating star-type than ever before.”
These findings have been published in The Astrophysical Journal Letters.
The observations were taken as part of General Observer program 17176.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Last Updated Nov 21, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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By NASA
On Nov. 6, 2024, NASA Night brought cosmic excitement to the Toyota Center, where Johnson Space Center employees joined 16,208 fans who interacted with NASA as they watched the Houston Rockets claim victory over the San Antonio Spurs.
Energy soared as International Space Station Program Manager Dana Weigel stepped up to take the first shot.
International Space Station Program Manager Dana Weigel takes the first shot on Nov. 6, 2024, as the Houston Rockets go up against the San Antonio Spurs at Toyota Center.NASA/Helen Arase Vargas The ceremonial first shot also gave back to the community, with Rockets owner Tilman Fertitta donating $1,000 to the Clutch City Foundation to support underserved youth through education, sports, and disaster relief.
Throughout the game, Johnson employees kept the crowd engaged with NASA trivia, creating a “launch countdown” energy that had fans cheering. The arena lit up as Adam Savage narrated a video showcasing the International Space Station’s groundbreaking contributions to science. From unlocking discoveries impossible on Earth to testing critical technologies for our return to the Moon, the orbiting laboratory plays a vital role in advancing medical and social breakthroughs that enhance life on our planet.
The Artemis II crew also appeared on the jumbotron, reminding everyone of NASA’s mission to establish a long-term presence on the Moon for scientific discovery, economic benefits, and to inspire a new generation of explorers.
Dana Weigel, center, shows off a Rockets jersey on the court with Rockets mascot Clutch, left, and NASA mascot Cosmo.NASA/Helen Arase Vargas In the Sky Court area of the stadium concourse, Johnson volunteers held “mission control” with an interactive exhibit that drew fans in like a gravitational pull. From exploring a Space Launch System model and handling a spacesuit helmet and glove to touching a 3.4-billion-year-old Moon rock collected during Apollo 17, NASA’s booth offered attendees a glimpse into space exploration.
Visitors had the chance to ask questions and bring home mission pins, stickers, and hands-on activities, provided by the International Space Station Program and the Artemis campaign. Seventy-five “Lucky Row” fans also received bags filled with NASA outreach materials, courtesy of the Johnson Public Engagement team.
NASA’s Johnson Space Center volunteers connect with fans at the game through an interactive exhibit.NASA The Orion Flight Simulator, with its realistic switches and displays, provided an immersive experience that allowed fans to dock the Orion spacecraft to humanity’s first lunar space station, Gateway.
More than 600 fans eagerly lined up to experience NASA’s mobile exhibit trailer in the Toyota Center parking lot—drawing lines as long as those at the box office.
Fans engage with the Orion Flight Simulator at NASA’s booth. NASA/Helen Arase Vargas Fans also tested their skills with a crew assembly activity focused on science, technology, engineering, and mathematics, simulating the challenges astronauts face in orbit. NASA’s inflatable mascot, Cosmo, joined the action on the court, posing for photos and adding galactic fun to events like the T-shirt giveaway.
The Houston Rockets mascot Clutch and NASA mascot Cosmo team up on the court at Toyota Center in Houston.NASA/Helen Arase Vargas NASA’s presence brought together the excitement of sports with the wonder of space exploration, inspiring fans to keep shooting for the stars.
View more images from the event below.
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By NASA
X-ray: NASA/CXC/SAO/J. Drake et al, IR: NASA/JPL-Caltech/Spitzer; Image Processing: NASA/CXC/SAO/N. Wolk Most stars form in collections, called clusters or associations, that include very massive stars. These giant stars send out large amounts of high-energy radiation, which can disrupt relatively fragile disks of dust and gas that are in the process of coalescing to form new planets.
A team of astronomers used NASA’s Chandra X-ray Observatory, in combination with ultraviolet, optical, and infrared data, to show where some of the most treacherous places in a star cluster may be, where planets’ chances to form are diminished.
The target of the observations was Cygnus OB2, which is the nearest large cluster of stars to our Sun — at a distance of about 4,600 light-years. The cluster contains hundreds of massive stars as well as thousands of lower-mass stars. The team used long Chandra observations pointing at different regions of Cygnus OB2, and the resulting set of images were then stitched together into one large image.
The deep Chandra observations mapped out the diffuse X-ray glow in between the stars, and they also provided an inventory of the young stars in the cluster. This inventory was combined with others using optical and infrared data to create the best census of young stars in the cluster.
In this new composite image, the Chandra data (purple) shows the diffuse X-ray emission and young stars in Cygnus OB2, and infrared data from NASA’s now-retired Spitzer Space Telescope (red, green, blue, and cyan) reveals young stars and the cooler dust and gas throughout the region.
In these crowded stellar environments, copious amounts of high-energy radiation produced by stars and planets are present. Together, X-rays and intense ultraviolet light can have a devastating impact on planetary disks and systems in the process of forming.
Planet-forming disks around stars naturally fade away over time. Some of the disk falls onto the star and some is heated up by X-ray and ultraviolet radiation from the star and evaporates in a wind. The latter process, known as “photoevaporation,” usually takes between 5 and 10 million years with average-sized stars before the disk disappears. If massive stars, which produce the most X-ray and ultraviolet radiation, are nearby, this process can be accelerated.
The researchers using this data found clear evidence that planet-forming disks around stars indeed disappear much faster when they are close to massive stars producing a lot of high-energy radiation. The disks also disappear more quickly in regions where the stars are more closely packed together.
For regions of Cygnus OB2 with less high-energy radiation and lower numbers of stars, the fraction of young stars with disks is about 40%. For regions with more high-energy radiation and higher numbers of stars, the fraction is about 18%. The strongest effect — meaning the worst place to be for a would-be planetary system — is within about 1.6 light-years of the most massive stars in the cluster.
A separate study by the same team examined the properties of the diffuse X-ray emission in the cluster. They found that the higher-energy diffuse emission comes from areas where winds of gas blowing away from massive stars have collided with each other. This causes the gas to become hotter and produce X-rays. The less energetic emission probably comes from gas in the cluster colliding with gas surrounding the cluster.
Two separate papers describing the Chandra data of Cygnus OB2 are available. The paper about the planetary danger zones, led by Mario Giuseppe Guarcello (National Institute for Astrophysics in Palermo, Italy), appeared in the November 2023 issue of the Astrophysical Journal Supplement Series, and is available here. The paper about the diffuse emission, led by Juan Facundo Albacete-Colombo (University of Rio Negro in Argentina) was published in the same issue of Astrophysical Journal Supplement, and is available here.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
JPL managed the Spitzer Space Telescope mission for NASA’s Science Mission Directorate in Washington until the mission was retired in January 2020. Science operations were conducted at the Spitzer Science Center at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. Data are archived at the Infrared Science Archive operated by IPAC at Caltech. Caltech manages JPL for NASA.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a composite image of the Cygnus OB2 star cluster, which resembles a night sky blanketed in orange, purple, and grey clouds.
The center of the square image is dominated by purple haze. This haze represents diffuse X-ray emissions, and young stars, detected by the Chandra X-ray observatory. Surrounding the purple haze is a mottled, streaky, brick orange cloud. Another cloud resembling a tendril of grey smoke stretches from our lower left to the center of the image. These clouds represent relatively cool dust and gas observed by the Spitzer Space Telescope.
Although the interwoven clouds cover most of the image, the thousands of stars within the cluster shine through. The lower-mass stars present as tiny specks of light. The massive stars gleam, some with long refraction spikes.
News Media Contact
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Chandra X-ray Center
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617-496-7998
mwatzke@cfa.harvard.edu
Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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By NASA
Mars: Perseverance (Mars 2020) Perseverance Home Mission Overview Rover Components Mars Rock Samples Where is Perseverance? Ingenuity Mars Helicopter Mission Updates Science Overview Objectives Instruments Highlights Exploration Goals News and Features Multimedia Perseverance Raw Images Images Videos Audio More Resources Mars Missions Mars Sample Return Mars Perseverance Rover Mars Curiosity Rover MAVEN Mars Reconnaissance Orbiter Mars Odyssey More Mars Missions The Solar System The Sun Mercury Venus Earth The Moon Mars Jupiter Saturn Uranus Neptune Pluto & Dwarf Planets Asteroids, Comets & Meteors The Kuiper Belt The Oort Cloud 2 min read
Red Rocks with Green Spots at ‘Serpentine Rapids’
NASA’s Mars Perseverance rover acquired this image, a nighttime mosaic of the Malgosa Crest abrasion patch at “Serpentine Rapids,” using its SHERLOC WATSON camera, located on the turret at the end of the rover’s robotic arm. The diameter of the abrasion patch is 5 centimeters (about 2 inches) and the large green spot in the upper center left of the image is approximately 2 millimeters (about 0.08 inch) in diameter. Mosaic source images have been debayered, flat-fielded, and linearly color stretched. This image was acquired on Aug. 19, 2024 (sol 1243, or Martian day 1,243 of the Mars 2020 mission) at the local mean solar time of 19:45:30. NASA/JPL-Caltech After discovering and sampling the “leopard spots” of “Bright Angel,” it became apparent that Perseverance’s journey of discovery in this region was not yet finished. Approximately 20 sols (Martian days) after driving south across Neretva Vallis from Bright Angel, the rover discovered the enigmatic and unique red rocks of “Serpentine Rapids.”
At Serpentine Rapids, Perseverance used its abrading bit to create an abrasion patch in a red rock outcrop named “Wallace Butte.” The 5-cm diameter abrasion patch revealed a striking array of white, black, and green colors within the rock. One of the biggest surprises for the rover team was the presence of the drab-green-colored spots within the abrasion patch, which are composed of dark-toned cores with fuzzy, light green rims.
On Earth, red rocks — sometimes called “red beds” — generally get their color from oxidized iron (Fe3+), which is the same form of iron that makes our blood red, or the rusty red color of metal left outside. Green spots like those observed in the Wallace Butte abrasion are common in ancient “red beds” on Earth and form when liquid water percolates through the sediment before it hardens to rock, kicking off a chemical reaction that transforms oxidized iron to its reduced (Fe2+) form, resulting in a greenish hue. On Earth, microbes are sometimes involved in this iron reduction reaction. However, green spots can also result from decaying organic matter that creates localized reducing conditions. Interactions between sulfur and iron can also create iron-reducing conditions without the involvement of microbial life.
Unfortunately, there was not enough room to safely place the rover arm containing the SHERLOC and PIXL instruments directly atop one of the green spots within the abrasion patch, so their composition remains a mystery. However, the team is always on the lookout for similar interesting and unexpected features in the rocks.
The science and engineering teams are now dealing with incredibly steep terrain as Perseverance ascends the Jezero Crater rim. In the meantime, the Science Team is hanging on to the edge of their seats with excitement and wonder as Perseverance makes the steep climb out of the crater it has called home for the past two years. There is no shortage of wonder and excitement across the team as we contemplate what secrets the ancient rocks of the Jezero Crater rim may hold.
Written by Adrian Broz, Postdoctoral Scientist, Purdue University/University of Oregon
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Last Updated Oct 25, 2024 Related Terms
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