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    • By NASA
      Hubble Space Telescope Home NASA’s Hubble, Webb… 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   6 Min Read NASA’s Hubble, Webb Probe Surprisingly Smooth Disk Around Vega
      Teams of astronomers used the combined power of NASA’s Hubble and James Webb space telescopes to revisit the legendary Vega disk. Credits:
      NASA, ESA, CSA, STScI, S. Wolff (University of Arizona), K. Su (University of Arizona), A. Gáspár (University of Arizona) In the 1997 movie “Contact,” adapted from Carl Sagan’s 1985 novel, the lead character scientist Ellie Arroway (played by actor Jodi Foster) takes a space-alien-built wormhole ride to the star Vega. She emerges inside a snowstorm of debris encircling the star — but no obvious planets are visible.
      It looks like the filmmakers got it right.
      A team of astronomers at the University of Arizona, Tucson used NASA’s Hubble and James Webb space telescopes for an unprecedented in-depth look at the nearly 100-billion-mile-diameter debris disk encircling Vega. “Between the Hubble and Webb telescopes, you get this very clear view of Vega. It’s a mysterious system because it’s unlike other circumstellar disks we’ve looked at,” said Andras Gáspár of the University of Arizona, a member of the research team. “The Vega disk is smooth, ridiculously smooth.”
      The big surprise to the research team is that there is no obvious evidence for one or more large planets plowing through the face-on disk like snow tractors. “It’s making us rethink the range and variety among exoplanet systems,” said Kate Su of the University of Arizona, lead author of the paper presenting the Webb findings.
      [left] A Hubble Space Telescope false-color view of a 100-billion-mile-wide disk of dust around the summer star Vega. Hubble detects reflected light from dust that is the size of smoke particles largely in a halo on the periphery of the disk. The disk is very smooth, with no evidence of embedded large planets. The black spot at the center blocks out the bright glow of the hot young star.
      [right] The James Webb Space Telescope resolves the glow of warm dust in a disk halo, at 23 billion miles out. The outer disk (analogous to the solar system’s Kuiper Belt) extends from 7 billion miles to 15 billion miles. The inner disk extends from the inner edge of the outer disk down to close proximity to the star. There is a notable dip in surface brightness of the inner disk from approximately 3.7 to 7.2 billion miles. The black spot at the center is due to lack of data from saturation. NASA, ESA, CSA, STScI, S. Wolff (University of Arizona), K. Su (University of Arizona), A. Gáspár (University of Arizona)
      Download this image

      Webb sees the infrared glow from a disk of particles the size of sand swirling around the sizzling blue-white star that is 40 times brighter than our Sun. Hubble captures an outer halo of this disk, with particles no bigger than the consistency of smoke that are reflecting starlight.
      The distribution of dust in the Vega debris disk is layered because the pressure of starlight pushes out the smaller grains faster than larger grains. “Different types of physics will locate different-sized particles at different locations,” said Schuyler Wolff of the University of Arizona team, lead author of the paper presenting the Hubble findings. “The fact that we’re seeing dust particle sizes sorted out can help us understand the underlying dynamics in circumstellar disks.”
      The Vega disk does have a subtle gap, around 60 AU (astronomical units) from the star (twice the distance of Neptune from the Sun), but otherwise is very smooth all the way in until it is lost in the glare of the star. This shows that there are no planets down at least to Neptune-mass circulating in large orbits, as in our solar system, say the researchers.
      Hubble acquired this image of the circumstellar disk around the star Vega using the Space Telescope Imaging Spectrograph (STIS). NASA, ESA, CSA, STScI, S. Wolff (University of Arizona), K. Su (University of Arizona), A. Gáspár (University of Arizona)
      Download this image

      “We’re seeing in detail how much variety there is among circumstellar disks, and how that variety is tied into the underlying planetary systems. We’re finding a lot out about the planetary systems — even when we can’t see what might be hidden planets,” added Su. “There’s still a lot of unknowns in the planet-formation process, and I think these new observations of Vega are going to help constrain models of planet formation.”
      Disk Diversity
      Newly forming stars accrete material from a disk of dust and gas that is the flattened remnant of the cloud from which they are forming. In the mid-1990s Hubble found disks around many newly forming stars. The disks are likely sites of planet formation, migration, and sometimes destruction. Fully matured stars like Vega have dusty disks enriched by ongoing “bumper car” collisions among orbiting asteroids and debris from evaporating comets. These are primordial bodies that can survive up to the present 450-million-year age of Vega (our Sun is approximately ten times older than Vega). Dust within our solar system (seen as the Zodiacal light) is also replenished by minor bodies ejecting dust at a rate of about 10 tons per second. This dust is shoved around by planets. This provides a strategy for detecting planets around other stars without seeing them directly – just by witnessing the effects they have on the dust.
      “Vega continues to be unusual,” said Wolff. “The architecture of the Vega system is markedly different from our own solar system where giant planets like Jupiter and Saturn are keeping the dust from spreading the way it does with Vega.”
      Webb acquired this image of the circumstellar disk around the star Vega using the Mid-Infrared Instrument (MIRI). NASA, ESA, CSA, STScI, S. Wolff (University of Arizona), K. Su (University of Arizona), A. Gáspár (University of Arizona)
      Download this image

      For comparison, there is a nearby star, Fomalhaut, which is about the same distance, age and temperature as Vega. But Fomalhaut’s circumstellar architecture is greatly different from Vega’s. Fomalhaut has three nested debris belts.
      Planets are suggested as shepherding bodies around Fomalhaut that gravitationally constrict the dust into rings, though no planets have been positively identified yet. “Given the physical similarity between the stars of Vega and Fomalhaut, why does Fomalhaut seem to have been able to form planets and Vega didn’t?” said team member George Rieke of the University of Arizona, a member of the research team. “What’s the difference? Did the circumstellar environment, or the star itself, create that difference? What’s puzzling is that the same physics is at work in both,” added Wolff.
      First Clue to Possible Planetary Construction Yards
      Located in the summer constellation Lyra, Vega is one of the brightest stars in the northern sky. Vega is legendary because it offered the first evidence for material orbiting a star — presumably the stuff for making planets — as potential abodes of life. This was first hypothesized by Immanuel Kant in 1775. But it took over 200 years before the first observational evidence was collected in 1984. A puzzling excess of infrared light from warm dust was detected by NASA’s IRAS (Infrared Astronomy Satellite). It was interpreted as a shell or disk of dust extending twice the orbital radius of Pluto from the star.
      In 2005, NASA’s infrared Spitzer Space Telescope mapped out a ring of dust around Vega. This was further confirmed by observations using submillimeter telescopes including Caltech’s Submillimeter Observatory on Mauna Kea, Hawaii, and also the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, and ESA’s (European Space Agency’s) Herschel Space Telescope, but none of these telescopes could see much detail. “The Hubble and Webb observations together provide so much more detail that they are telling us something completely new about the Vega system that nobody knew before,” said Rieke.
      Two papers (Wolff et al. and Su et. al.) from the Arizona team will be published in The Astrophysical Journal.
      The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
      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, Colorado, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, Maryland, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
      Explore More:

      Finding Planetary Construction Zones


      The science paper by Schuyler Wolff et al., PDF (3.24 MB)


      The science paper by Kate Su et al., PDF (2.10 MB)

      Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Facebook logo @NASAWebb @NASAWebb Instagram logo @NASAWebb Media Contacts:
      Claire Andreoli (claire.andreoli@nasa.gov), Laura Betz (laura.e.betz@nasa.gov)
      NASA’s Goddard Space Flight Center, Greenbelt, MD
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      Space Telescope Science Institute, Baltimore, MD
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      Last Updated Nov 01, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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      Preparations for Next Moonwalk Simulations Underway (and Underwater)
      A SWOT data visualization shows water on the northern side of Greenland’s Dickson Fjord at higher levels than on the southern side on Sept. 17, 2023. A huge rockslide into the fjord the previous day led to a tsunami lasting nine days that caused seismic rumbling around the world. NASA Earth Observatory Data from space shows water tilting up toward the north side of the Dickson Fjord as it sloshed from south to north and back every 90 seconds for nine days after a 2023 rockslide.
      The international Surface Water and Ocean Topography (SWOT) satellite mission, a collaboration between NASA and France’s CNES (Centre National d’Études Spatiales), detected the unique contours of a tsunami that sloshed within the steep walls of a fjord in Greenland in September 2023. Triggered by a massive rockslide, the tsunami generated a seismic rumble that reverberated around the world for nine days. An international research team that included seismologists, geophysicists, and oceanographers recently reported on the event after a year of analyzing data.
      The SWOT satellite collected water elevation measurements in Dickson Fjord on Sept. 17, 2023, the day after the initial rockslide and tsunami. The data was compared with measurements made under normal conditions a few weeks prior, on Aug. 6, 2023.
      In the data visualization (above), colors toward the red end of the scale indicate higher water levels, and blue colors indicate lower-than-normal levels. The data suggests that water levels at some points along the north side of the fjord were as much as 4 feet (1.2 meters) higher than on the south.
      “SWOT happened to fly over at a time when the water had piled up pretty high against the north wall of the fjord,” said Josh Willis, a sea level researcher at NASA’s Jet Propulsion Laboratory in Southern California. “Seeing the shape of the wave — that’s something we could never do before SWOT.”
      In a paper published recently in Science, researchers traced a seismic signal back to a tsunami that began when more than 880 million cubic feet of rock and ice (25 million cubic meters) fell into Dickson Fjord. Part of a network of channels on Greenland’s eastern coast, the fjord is about 1,772 feet (540 meters) deep and 1.7 miles (2.7 kilometers) wide, with walls taller than 6,000 feet (1,830 meters).
      Far from the open ocean, in a confined space, the energy of the tsunami’s motion had limited opportunity to dissipate, so the wave moved back and forth about every 90 seconds for nine days. It caused tremors recorded on seismic instruments thousands of miles away.
      From about 560 miles (900 kilometers) above, SWOT uses its sophisticated Ka-band Radar Interferometer (KaRIn) instrument to measure the height of nearly all water on Earth’s surface, including the ocean and freshwater lakes, reservoirs, and rivers.
      “This observation also shows SWOT’s ability to monitor hazards, potentially helping in disaster preparedness and risk reduction,” said SWOT program scientist Nadya Vinogradova Shiffer at NASA Headquarters in Washington.
      It can also see into fjords, as it turns out.
      “The KaRIn radar’s resolution was fine enough to make observations between the relatively narrow walls of the fjord,” said Lee-Lueng Fu, the SWOT project scientist. “The footprint of the conventional altimeters used to measure ocean height is too large to resolve such a small body of water.”
      More About SWOT
      Launched in December 2022 from Vandenberg Space Force Base in California, SWOT is now in its operations phase, collecting data that will be used for research and other purposes.
      The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA’s Jet Propulsion Laboratory, managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations. CSA provided the KaRIn high-power transmitter assembly. NASA provided the launch vehicle and the agency’s Launch Services Program, based at Kennedy Space Center in Florida, managed the associated launch services.
      To learn more about SWOT, visit:
      https://swot.jpl.nasa.gov
      News Media Contacts
      Jane J. Lee / Andrew Wang
      Jet Propulsion Laboratory, Pasadena, Calif.
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      Last Updated Oct 31, 2024 Related Terms
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      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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      Claire Andreoli
      NASA’s Goddard Space Flight Center, Greenbelt, MD
      claire.andreoli@nasa.gov
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      Last Updated Oct 10, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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      Image Credit: NASA/Wanmei Liang, USGS
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