Explore

James Webb Space Telescope Reveals Early Galaxies Larger Than Previously Thought Due to Hidden Stars

James Webb Space Telescope Reveals Early Galaxies Larger Than Previously Thought Due to Hidden Stars

The James Webb Space Telescope (JWST) has made a significant discovery regarding the early universe, revealing that the first galaxies were much larger and more massive than previously estimated. By studying nine early galaxies that have completed their intense star formation periods, astronomers found a much greater proportion of small, faint stars compared to modern galaxies like the Milky Way. This finding challenges previous assumptions that the proportion of stars of different masses remained constant throughout cosmic history. The JWST's sensitivity allowed researchers to detect these previously 'hidden stars,' which were overshadowed by more massive, brighter stars in earlier observations. This means that the total mass of these early galaxies is considerably higher than what was calculated based on their overall light spectrum, which is typically dominated by the most massive stars.

Descubren GJ 523b, una mega-Tierra que desconcierta a científicos

Descubren GJ 523b, una mega-Tierra que desconcierta a científicos

La mega-Tierra GJ 523b tiene 23 veces la masa de la Tierra, pero apenas 2.5 veces su diámetro. Su aparente falta de gas desconcierta a los científicos.

Stellar Spin Explains Dimming Flares from Black Hole Interactions

Stellar Spin Explains Dimming Flares from Black Hole Interactions

Astrophysicists at Syracuse University have proposed a new explanation for why repeated flares from stars interacting with supermassive black holes grow progressively dimmer. These events, known as repeating partial tidal disruption events (rpTDEs), occur when a star makes multiple close passes to a black hole, losing some of its mass and producing a flare of light each time. Previous theoretical models struggled to explain the observed dimming of successive flares. The new study, published in The Astrophysical Journal, suggests that a star's rapid initial spin, prior to its first encounter with the black hole, is the crucial 'new ingredient.' This rapid initial spin prevents the star from being significantly spun up during subsequent close encounters, which in turn keeps the timescale for material fallback relatively constant. As less material is lost with each encounter, the peak fallback rate and thus the flare's brightness decline.

Hubble Space Telescope Provides Definitive Evidence of Ancient Dwarf Galaxy Merger with Milky Way

Hubble Space Telescope Provides Definitive Evidence of Ancient Dwarf Galaxy Merger with Milky Way

The Hubble Space Telescope, a collaborative project between ESA and NASA, has provided definitive evidence of a dwarf galaxy merging with the young Milky Way galaxy in the earliest phases of its evolution. This discovery extends the known history of our galaxy by 1.8 billion years. Researchers utilized Hubble to examine globular clusters, which are vast, spherical collections of stars, some of the oldest in the Milky Way. These clusters serve as 'cosmic archaeological sites,' preserving stars from other galaxies that the Milky Way has absorbed over time. The study, published in Nature Astronomy, identified a third population of globular clusters in the inner regions of our galaxy, distinct from those formed within the Milky Way or collected during the Gaia-Sausage-Enceladus merger 10 billion years ago. These newly identified clusters are older than those from the Gaia-Sausage-Enceladus merger but younger than the Milky Way's original clusters, indicating they originated from an even earlier merger. This dw...

Hubble and Gaia Telescopes Reveal Milky Way's Earliest Galactic Merger 11.8 Billion Years Ago

Hubble and Gaia Telescopes Reveal Milky Way's Earliest Galactic Merger 11.8 Billion Years Ago

Scientists, utilizing data from the Hubble and Gaia orbiting telescopes, have uncovered evidence that the Milky Way galaxy underwent its earliest known galactic merger approximately 11.8 billion years ago. This event occurred when the universe was less than 15% of its current age. The research, published in the journal Nature Astronomy, indicates that the Milky Way absorbed a smaller dwarf galaxy, which has been named Low-energy-Kraken-Heracles (LKH). At the time of the merger, the LKH dwarf galaxy contained stars with a mass equivalent to 500 million times that of the sun, making it about a quarter the size of the Milky Way. Researchers studied stellar clusters within the Milky Way's innermost 20,000 light-years, analyzing their age, chemical composition, and trajectory to reconstruct this ancient cosmic event. This discovery sheds light on the Milky Way's growth, demonstrating that it expanded not only through its own star formation but also by integrating smaller galaxies caught in its gravitational pul...

Hubble and James Webb Telescopes Collaborate to Capture 'Black Eye Galaxy' Image

Hubble and James Webb Telescopes Collaborate to Capture 'Black Eye Galaxy' Image

The Hubble Space Telescope and the James Webb Space Telescope (JWST) have collaborated to produce a composite image of the 'Black Eye Galaxy,' also known as Messier 64. This spiral galaxy is situated 17 million light-years from Earth in the constellation Coma Berenices. The galaxy is notable for its unique internal motion, where the gas in its outer regions rotates in the opposite direction to the gas and stars closer to its core. To create this detailed image, astronomers combined observations from JWST, which captured near and mid-infrared wavelengths, with Hubble's data from ultraviolet, visible, and near-infrared wavelengths. This joint effort showcases the complementary capabilities of these powerful space observatories.

Record-Breaking Star S301 Offers New Insights into Milky Way's Supermassive Black Hole Spin

Record-Breaking Star S301 Offers New Insights into Milky Way's Supermassive Black Hole Spin

Astronomers have discovered a new record-breaking star, S301, which is the closest known star to the Milky Way's supermassive black hole, Sagittarius A*. Reported on August 19 in Nature, S301 reaches speeds of 25,000 kilometers per second, approximately 8% the speed of light. Its extreme proximity to Sagittarius A* makes it a unique tool for measuring the black hole's elusive characteristic: spin. Stefan Gillessen, an astronomer at the Max Planck Institute for Extraterrestrial Physics, highlighted the star's potential for understanding black hole physics. S301, about 50% larger than the sun, was first observed in 2023 by the GRAVITY+ collaboration using the European Southern Observatory’s Very Large Telescope Interferometer. By combining two subsequent years of observations with historical data dating back to 2017, astronomers mapped its 8.7-year, highly elongated orbit, which brings it within 1.7 billion kilometers of Sagittarius A*. This close orbit is crucial because the black hole's spin is expected to...

James Webb Space Telescope Reveals Distant Galaxies More Massive Than Previously Estimated

James Webb Space Telescope Reveals Distant Galaxies More Massive Than Previously Estimated

An international team of researchers, led by scientists at Leiden University, has utilized the James Webb Space Telescope (JWST) to discover that the most massive galaxies in the early universe contain a significantly higher proportion of small stars than previously assumed. This finding suggests that these distant galaxies are much more massive than initial measurements indicated, challenging existing models of galaxy formation. The team studied nine massive, mature galaxies that had ceased forming stars billions of years ago, combining deep JWST spectra with observations from the Very Large Telescope. By analyzing subtle differences in the light spectrum, they were able to reliably determine the proportions of tiny, faint stars and giant, bright stars within these galaxies for the first time. This research, published in Nature Astronomy, indicates that a large population of low-mass stars was previously concealed by the more luminous, massive stars.

Fastest-known star zooms under Milky Way black hole's influence

Fastest-known star zooms under Milky Way black hole's influence

WASHINGTON, Aug 19 (Reuters) - Scientists have detected the fastest-known star, a stellar speedster that is zooming around the supermassive black hole residing at the center of our galaxy and might hold the key to measuring the spin of this celestial beast for the first time.

Telescope spies the fastest star in the Milky Way zipping around a black hole

Telescope spies the fastest star in the Milky Way zipping around a black hole

A telescope has spotted the fastest known star in the Milky Way

New Research Reveals Shorter, More Dynamic Afterlife for Black Hole Jets in Dying Radio Galaxies

New Research Reveals Shorter, More Dynamic Afterlife for Black Hole Jets in Dying Radio Galaxies

Recent research published in the journal Monthly Notices of the Royal Astronomical Society indicates that the afterlife of black hole jets in dying radio galaxies is shorter and more dynamic than previously understood. Scientists utilized multifrequency observations from surveys like MeerKAT MIGHTEE and uGMRT superMIGHTEE, along with data from LOFAR, GMRT, and the Jansky Very Large Array, to study 14 candidate remnant radio galaxies in the XMM–Newton Large-Scale Structure (XMM–LSS) field. These remnant galaxies represent the final stage of radio-galaxy evolution where the central active galactic nucleus (AGN) jets have ceased to replenish the radio lobes with energetic particles. The study confirmed 12 of the 14 candidates as genuine remnant radio galaxies, with two reclassified as active sources. A key finding is the relatively young age of these remnants, ranging from approximately 8 to 42 million years, with a median age of about 12 million years, suggesting a population of short-lived remnants that wer...

Astronomers Discover Rocky 'Mega-Earth' Exoplanet GJ 523b, Challenging Planetary Formation Models

Astronomers Discover Rocky 'Mega-Earth' Exoplanet GJ 523b, Challenging Planetary Formation Models

Astronomers have identified a new exoplanet, GJ 523b, which is approximately 23.5 times the mass of Earth but only 2.55 times its radius. This high density suggests that GJ 523b is predominantly rocky with a relatively small amount of gas in its atmosphere, leading researchers to informally categorize it as a 'mega-Earth.' The planet orbits its star in 17.75 days, and its system is estimated to be nearly 170 million years old. The exoplanet candidate was initially detected by NASA’s TESS satellite, which observes periodic dips in stellar brightness caused by transiting planets. Subsequent observations using the ground-based 3.5-meter WIYN telescope at Kitt Peak Observatory in Arizona allowed scientists to measure the planet’s gravitational influence on its star. The parameters of GJ 523b, particularly its mass exceeding the threshold where gas giants typically accumulate massive gas envelopes, present a significant challenge to current planetary formation models.