ReportWire

Tag: Space Channel Featured Story TOP

  • The Crab Nebula Seen in New Light by NASA’s Webb

    The Crab Nebula Seen in New Light by NASA’s Webb

    Newswise — NASA’s James Webb Space Telescope has gazed at the Crab Nebula, a supernova remnant located 6,500 light-years away in the constellation Taurus. Since the recording of this energetic event in 1054 CE by 11th-century astronomers, the Crab Nebula has continued to draw attention and additional study as scientists seek to understand the conditions, behavior, and after-effects of supernovae through thorough study of the Crab, a relatively nearby example.

    Using Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument), a team led by Tea Temim at Princeton University is searching for answers about the Crab Nebula’s origins.

    “Webb’s sensitivity and spatial resolution allows us to accurately determine the composition of the ejected material, particularly the content of iron and nickel, which may reveal what type of explosion produced the Crab Nebula,” explained Temim.

    At first glance, the general shape of the supernova remnant is similar to the optical wavelength image released in 2005 from NASA’s Hubble Space Telescope: In Webb’s infrared observation, a crisp, cage-like structure of fluffy gaseous filaments are shown in red-orange. However, in the central regions, emission from dust grains (yellow-white and green) is mapped out by Webb for the first time.

    Additional aspects of the inner workings of the Crab Nebula become more prominent and are seen in greater detail in the infrared light captured by Webb. In particular, Webb highlights what is known as synchrotron radiation: emission produced from charged particles, like electrons, moving around magnetic field lines at relativistic speeds. The radiation appears here as milky smoke-like material throughout the majority of the Crab Nebula’s interior.

    This feature is a product of the nebula’s pulsar, a rapidly rotating neutron star. The pulsar’s strong magnetic field accelerates particles to extremely high speeds and causes them to emit radiation as they wind around magnetic field lines. Though emitted across the electromagnetic spectrum, the synchrotron radiation is seen in unprecedented detail with Webb’s NIRCam instrument.

    To locate the Crab Nebula’s pulsar heart, trace the wisps that follow a circular ripple-like pattern in the middle to the bright white dot in the center. Farther out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, outlining the structure of the pulsar’s magnetic field, which sculpts and shapes the nebula.

    At center left and right, the white material curves sharply inward from the filamentary dust cage’s edges and goes toward the neutron star’s location, as if the waist of the nebula is pinched. This abrupt slimming may be caused by the confinement of the supernova wind’s expansion by a belt of dense gas.

    The wind produced by the pulsar heart continues to push the shell of gas and dust outward at a rapid pace. Among the remnant’s interior, yellow-white and green mottled filaments form large-scale loop-like structures, which represent areas where dust grains reside.

    The search for answers about the Crab Nebula’s past continues as astronomers further analyze the Webb data and consult previous observations of the remnant taken by other telescopes. Scientists will have newer Hubble data to review within the next year or so from the telescope’s reimaging of the supernova remnant. This will mark Hubble’s first look at emission lines from the Crab Nebula in over 20 years, and will enable astronomers to more accurately compare Webb and Hubble’s findings.

    For more information, including a video image tour, and to download full-resolution images, visit https://webbtelescope.org/contents/news-releases/2023/news-2023-137.

    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 the Canadian Space Agency.

    Space Telescope Science Institute (STScI)

    Source link

  • Webb Detects Extremely Small Main Belt Asteroid

    Webb Detects Extremely Small Main Belt Asteroid

    Newswise — An asteroid roughly the size of Rome’s Colosseum — between 300 to 650 feet (100 to 200 meters) in length — has been detected by an international team of European astronomers using NASA’s James Webb Space Telescope. Their project used data from the calibration of the Mid-InfraRed Instrument (MIRI), in which the team serendipitously detected an interloping asteroid. The object is likely the smallest observed to date by Webb and may be an example of an object measuring under 0.6 miles (1 kilometer) in length within the main asteroid belt, located  between Mars and Jupiter. More observations are needed to better characterize this object’s nature and properties.

    “We — completely unexpectedly — detected a small asteroid in publicly available MIRI calibration observations,” explained Thomas Müller, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany. “The measurements are some of the first MIRI measurements targeting the ecliptic plane and our work suggests that many new objects will be detected with this instrument.”

    These Webb observations, published in the journal Astronomy and Astrophysics, were not designed to hunt for new asteroids — in fact, they were calibration images of the main belt asteroid (10920) 1998 BC1, which astronomers discovered in 1998. The observations were conducted to test the performance of some of MIRI’s filters, but the calibration team considered them to have failed for technical reasons due to the brightness of the target and an offset telescope pointing. Despite this, the data on asteroid 10920 were used by the team to establish and test a new technique to constrain an object’s orbit and to estimate its size. The validity of the method was demonstrated for asteroid 10920 using the MIRI observations combined with data from ground-based telescopes and ESA’s Gaia mission.

    In the course of the analysis of the MIRI data, the team found the smaller interloper in the same field of view. The team’s results suggest the object measures 100–200 meters, occupies a very low-inclination orbit, and was located in the inner main-belt region at the time of the Webb observations.

    “Our results show that even ‘failed’ Webb observations can be scientifically useful, if you have the right mindset and a little bit of luck,” elaborated Müller. “Our detection lies in the main asteroid belt, but Webb’s incredible sensitivity made it possible to see this roughly 100-meter object at a distance of more than 100 million kilometers.”

    The detection of this asteroid — which the team suspects to be the smallest observed to date by Webb and one of the smallest detected in the main belt — would, if confirmed as a new asteroid discovery, have important implications for our understanding of the formation and evolution of the solar system. Current models predict the occurrence of asteroids down to very small sizes, but small asteroids have been studied in less detail than their larger counterparts owing to the difficulty of observing these objects. Future dedicated Webb observations will allow astronomers to study asteroids smaller than 1 kilometer in size.

    What’s more, this result suggests that Webb will also be able to serendipitously contribute to the detection of new asteroids. The team suspects that even short MIRI observations close to the plane of the solar system will always include a few asteroids, most of which will be unknown objects.

    In order to confirm that the object detected is a newly discovered asteroid, more position data relative to background stars is required from follow-up studies to constrain the object’s orbit.
     
    “This is a fantastic result which highlights the capabilities of MIRI to serendipitously detect a previously undetectable size of asteroid in the main belt,” concluded Bryan Holler, Webb support scientist at the Space Telescope Science Institute in Baltimore, Maryland. “Repeats of these observations are in the process of being scheduled, and we are fully expecting new asteroid interlopers in those images.”

    The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe 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 the Canadian Space Agency.

    ###

    Space Telescope Science Institute (STScI)

    Source link