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  • This work finds a systematic offset of 5.5 ± 1.1 Myr between estimates of the ages of stars made with two popular techniques: isochronal fitting and dynamical traceback. This offset is proposed to represent the time a young star remains bound to its parental cloud before dispersing and could help to improve stellar evolutionary models.

    • Núria Miret-Roig
    • João Alves
    • Ralf Konietzka
    Article
  • Synchrotron and inverse-Compton emission provide evidence for a reverse-shock origin of the high-energy emission from a gamma-ray burst, GRB 180720B. The polarization of the optical emission originating from the reverse shock suggests a turbulent shock that is amplified by the magnetic field in the relativistic ejecta.

    • Makoto Arimoto
    • Katsuaki Asano
    • Soebur Razzaque
    Article
  • Prolonged radio emissions above a sunspot, akin to those auroral emissions previously seen in the polar regions of planets and certain stars, have been detected using the Very Large Array. This detection could potentially provide support for an alternative mechanism for the origin of some stellar radio bursts.

    • Sijie Yu
    • Bin Chen
    • Marina Battaglia
    Article
  • Extremely low-mass stars, much less massive than the Sun, lack radiative cores—something that could affect their magnetic dynamos. This study reveals that these stars can have magnetic fields that are up to 30% stronger than those of Sun-like stars, implying fundamental differences in their internal magnetic structures.

    • Yuxi (Lucy) Lu
    • Victor See
    • Sean P. Matt
    Article
  • The altered and thermally metamorphosed CY chondrites are shown to be the meteoritic analogue of asteroid Phaethon. This suggests that Phaethon’s activity is driven by gas released from the decomposition of near-surficial material heated at perihelion, whereas the interior is kept relatively unaltered and hydrated.

    • Eric MacLennan
    • Mikael Granvik
    Article
  • Juno’s close flyby of Ganymede on 7 June 2021 allowed the infrared mapping spectrometer JIRAM to observe the surface at unprecedented spatial resolution. JIRAM’s detailed spectroscopic characterization reveals past extensive aqueous alteration on the moon, possibly together with hydrothermal activity.

    • Federico Tosi
    • Alessandro Mura
    • Diego Turrini
    Article
  • Venus’s atmosphere is linked to its interior and can be used to infer the planet’s evolution. Observed atmospheric N2, CO2 and surface pressures are best explained by an early phase of plate tectonics, operating for at least 1 billion years.

    • Matthew B. Weller
    • Alexander J. Evans
    • Alexandria V. Johnson
    Article
  • Space interferometry reveals the hidden and filamentary internal structure of the relativistic jet in 3C 279 at microarcsecond angular resolution. These details challenge previous assumptions on the morphology and radio variability of blazars.

    • Antonio Fuentes
    • José L. Gómez
    • Tuomas Savolainen
    Article
  • Using NASA’s Juno mission measurements, researchers obtain a new high-precision map of Jupiter’s gravity field and confirm that the planet’s observed strong east–west jet streams penetrate inwards in a direction parallel to the planet’s spin axis.

    • Y. Kaspi
    • E. Galanti
    • S. J. Bolton
    Article
  • New northern aurora emissions on Uranus in the infrared spectrum are detected after a 30-year search. The emissions, observed close to equinox, are most likely caused by the 88% increase in upper atmosphere column density.

    • Emma M. Thomas
    • Henrik Melin
    • Steve Miller
    ArticleOpen Access
  • A rare perfect alignment between two galaxies in the young Universe has been captured by the James Webb Space Telescope. The further (z ≈ 3) galaxy is curved into an Einstein ring due to the bending of space around the nearer (z ≈ 2) galaxy, which is massive and compact—representative of the pristine core of a present-day galaxy.

    • Pieter van Dokkum
    • Gabriel Brammer
    • Charlie Conroy
    ArticleOpen Access
  • The repeating fast radio burst (FRB) source FRB 20121102A emits ultra-FRBs that last for only microseconds. These bursts are thousands of times shorter than typical for such astronomical radio flashes and indicate that there is a population of FRBs that has been missed previously.

    • M. P. Snelders
    • K. Nimmo
    • V. Gajjar
    Article