Sistema Solar

JWST reveals the ‘boring’ Galilean moon Callisto is chemically alive

New JWST observations led by Maria Camarca (Caltech), accepted in The Planetary Science Journal, reveal that Callisto — Jupiter's quietest Galilean moon — hides a surprisingly active surface chemistry. Using NIRSpec to map its trailing hemisphere, the Asgard basin, and Valhalla (the solar system's largest multi-ring impact structure), the team charted water ice, frozen CO2 anti-correlated with that ice, a faint patchy CO2 atmosphere, and a carbon-nitrogen signature stronger than on any other Galilean moon — with the JUICE mission set to look closer in the 2030s.

Nuevos

Why a black hole’s repeat flares keep fading: the answer was the star’s spin all along

When a star strays close to a supermassive black hole but isn't destroyed outright, it can survive to make repeated passes, flaring each time...

ALMA finds sulfur around a rare dying supergiant — and a chemical fingerprint once thought unique to Earth’s rocks

Astronomers have uncovered a chemically rich shroud of sulfur-bearing molecules around the rare massive star HD 87643, including the first ever detection of sulfur...

Cosmología

Exploración Espacial

Curiosity descubre un vasto campo de polígonos en Marte que podría datar de cuando el planeta era como la Tierra

El rover Curiosity de la NASA ha enviado imágenes de un extenso campo de polígonos con textura de panal de abejas en el cráter Gale, la primera vez que el rover se topa con estas formaciones a nivel del suelo. Se plantea como hipótesis que son grietas de barro talladas por ciclos de humedad y sequía durante la transición Noaciano-Hesperiano, hace unos 3.700 millones de años — el período en que Marte pudo haber exhibido un clima parecido al de la Tierra.
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Radioastronomía

Vida extraterrestre

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    El SETI Institute confirma que el cometa interestelar 3I/Atlas no porta tecnología alienígena

    El SETI Institute rastreó cerca de 74 millones de señales de radio provenientes del cometa interestelar 3I/Atlas y no encontró ninguna tecno-firma. El objeto, estimado entre 440 m y 5.6 km y posiblemente de 11 mil millones de años, es completamente natural.

    Física

    The early universe’s giant galaxies are hiding their true weight in small stars

    Using the James Webb Space Telescope, an international team led by Leiden University has, for the first time, reliably measured the mix of tiny and giant stars in nine massive early galaxies — finding their stellar populations are bottom-heavy, packed with far more low-mass stars than galaxies like the Milky Way. As a result, these cosmic titans may be much more massive than thought; one, formed less than 1.5 billion years after the Big Bang, may be up to four times heavier than previous estimates. Published in Nature Astronomy.

    Un grumo invisible de materia oscura podría haber curvado el chorro de un blázar emisor de neutrinos

    Astrónomos liderados por Silke Britzen (Instituto Max Planck de Radioastronomía) han encontrado indicios de que un grumo invisible de materia oscura curvó gravitacionalmente el chorro del blázar PKS 2233-148, una de las pocas fuentes candidatas de neutrinos cósmicos. Combinando radio, rayos gamma y rayos X, detectaron un desplazamiento súbito del chorro junto a un destello ultrarrápido que podría ser la primera firma de subestructura de materia oscura detectada de esta forma. Publicado en MNRAS.

    Turning the cosmic web into a detector: first limits set on dark matter decaying into gravitons

    A team led by David Dunsky (New York University) has set the first observational limits on the exotic possibility that dark matter decays into gravitons. Using the magnetic fields of the cosmic web as a natural detector, gravitons crossing these filaments could convert into gamma-ray photons via the Gertsenshtein effect — a faint glow absent from Fermi-LAT data, which constrains the decay rate across a wide range of dark matter masses. Published in Physical Review D.

    Galaxy spins retain a measurable fingerprint from the universe’s first moments

    A team led by Ming-Jie Sheng (Xiamen University) has found the clearest evidence yet that galaxy rotation carries an imprint from the universe's first moments. By reconstructing the primordial distribution of matter with the ELUCID project and comparing it to measured galaxy spins, they detected the signature of primordial tidal torques with high statistical confidence — strongest in the gas of massive elliptical galaxies — confirming a decades-old prediction and opening a possible new probe of cosmic neutrinos.

    A minority of «leaky» galaxies may have reionized the early universe, JWST spectra suggest

    A team led by Emma Giovinazzo (University of Geneva) has analyzed JWST/NIRSpec spectra of 1,428 galaxies at redshift 5 to 10 and found that cosmic reionization may have been driven by a minority of "strong leaker" galaxies. Though only about 20% of galaxies let more than 10% of their ionizing radiation escape, these produced roughly 87% of the photons that reached the intergalactic medium — enough to account for nearly all reionization by z ≈ 5.8.

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