If you have any trouble logging in, please contact admins via email. tankathaf *at* gmail.com orrecusantathaf *at* gmail.com
Started by Tank, December 29, 2015, 05:13:42 PM
Quote from: Tank on August 26, 2023, 11:09:08 AMJWST does it again!
Quote from: Ecurb Noselrub on July 25, 2013, 08:18:52 PMIn Asmo's grey lump, wrath and dark clouds gather force.Luxembourg trembles.
QuoteThis side-by-side comparison of the Crab Nebula as seen by the Hubble Space Telescope in optical light (left) and the James Webb Space Telescope in infrared light (right) reveals different details. By studying the recently collected Webb data, and consulting previous observations of the Crab taken by other telescopes like Hubble, astronomers can build a more comprehensive understanding of this mysterious supernova remnant.Hubble Image: NASA, ESA, J. Hester, A. Loll (Arizona State University); Webb Image: NASA, ESA, CSA, STScI, T. Temim (Princeton University)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 allow 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.[Continues . . .]
QuoteThe second- and fourth-most distant galaxies ever seen (UNCOVER z-13 and UNCOVER z-12) have been confirmed using the James Webb Space Telescope's Near-Infrared Camera (NIRCam). The galaxies are located in Pandora's Cluster (Abell 2744), shown here as near-infrared wavelengths of light that have been translated to visible-light colors. The scale of the main cluster image is labelled in arcseconds, which is a measure of angular distance in the sky. The circles on the black-and-white images, showing the galaxies in the NIRCam-F277W filter band onboard JWST, indicate an aperture size of 0.32 arcsec. Image Credit: Cluster image: NASA, UNCOVER (Bezanson et al., DIO: 10.48550/arXiv.2212.04026). Insets: Nasa, UNCOVER (Wang et al., 2023). Composition: Dani Zemba/Penn State.The second- and fourth-most distant galaxies ever observed have been discovered in a region of space known as Pandora's Cluster, or Abell 2744, using data from NASA's James Webb Space Telescope (JWST). Following up on a deep field image of the area, an international team led by Penn State researchers confirmed the distance of these ancient galaxies and inferred their properties using new spectroscopic data — information about light emitted across the electromagnetic spectrum — from JWST. At nearly 33 billion light years away, these incredibly distant galaxies offer insights into how the earliest galaxies might have formed.Unlike other galaxies confirmed at this distance that appear in images as red dots, the new galaxies are larger and appear like a peanut and a fluffy ball, according to the researchers. A paper describing the galaxies appears today (Nov. 13) in the journal Astrophysical Journal Letters."Very little is known about the early universe, and the only way to learn about that time and to test our theories of early galaxy formation and growth is with these very distant galaxies," said first author Bingjie Wang, postdoctoral scholar in the Penn State Eberly College of Science and a member of the JWST UNCOVER (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) team that conducted the research. "Prior to our analysis, we knew of only three galaxies confirmed at around this extreme distance. Studying these new galaxies and their properties has revealed the diversity of galaxies in the early universe and how much there is to be learned from them."[Continues . . .]
QuoteAbstract:Observations of high-redshift galaxies provide a critical direct test to the theories of early galaxy formation, yet to date, only three have been spectroscopically confirmed at z > 12. Due to strong gravitational lensing over a wide area, the galaxy cluster field A2744 is ideal for searching for the earliest galaxies. Here we present JWST/NIRSpec observations of two galaxies: a robust detection at zspec = 12.393, and a plausible candidate at zspec = 13.079. The galaxies are discovered in JWST/NIRCam imaging and their distances are inferred with JWST/NIRSpec spectroscopy, all from the JWST Cycle 1 UNCOVER Treasury survey. Detailed stellar population modeling using JWST NIRCam and NIRSpec data corroborates the primeval characteristics of these galaxies: low mass (∼108M⊙), young, rapidly assembling, metal-poor, and star-forming. Interestingly, both galaxies are spatially resolved, having lensing-corrected rest-UV effective radii on the order of 300–400 pc, which are notably larger than other spectroscopically confirmed systems at similar redshifts. The observed dynamic range of z ≳ 10 sizes spans over 1 order of magnitude, implying a significant scatter in the size–mass relation at early times. Deep into the epoch of reionization, these discoveries elucidate the emergence of the first galaxies.