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Astronomers at NASA’s Hubble Space Telescope and the Atacama Large Millimeter/Submillimeter Array (ALMA) have discovered at least six early galaxies, massive in size, which were “dead” when the universe was about 3 billion years old. These galaxies had run out of cold hydrogen, something necessary for the formation of stars. With no fuel to form stars, the galaxies were running “empty”, NASA said.   

Lead author Kate Whitaker said that at this point in the universe — 3 billion years after the Big Bang — all galaxies should be forming lots of stars, adding that it’s the “peak epoch” of star formation. So what happened to all the cold gas in these galaxies so early on, asks Whitaker, also an assistant professor of astronomy at the University of Massachusetts, Amherst.

This study of early, distant, and dead galaxies, has been published in the journal Nature and was part of the REQUIEM — Resolving QUIEscent Magnified Galaxies At High Redshift — programme. The REQUIEM team uses huge foreground galaxy clusters as natural telescopes.

It doesn’t look like these kinds of dead galaxies rejuvenate even after later minor mergers and accretions of nearby small galaxies and gas, NASA said. Eleven billion years later, when analysed in the present-day universe, these compact galaxies are thought to have evolved to be larger but are still “dead”, for they form no stars now. 

While the US space agency said that the six galaxies in question lived “fast and furious” lives and formed stars in a short time, why they ran out of cold oxygen and then stopped creating stars remains a mystery.  

Did a supermassive black hole in the galaxy’s centre turn on and heat all the gas? Whitaker said that if that is the case the gas could still be there, but it’s hot.

The next possible explanation, according to Whitaker, is that the gas could have been expelled, and now it’s being stopped from accreting back onto the galaxy. Or the galaxy just use it all up and the supply is cut off, she says, adding that these are among the questions the team will continue to explore following new observations.

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NASA Satellite Detects Tree Leaf Changes as Early Volcano Eruption Warning Signal

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May 17, 2025

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NASA Satellite Detects Tree Leaf Changes as Early Volcano Eruption Warning Signal

NASA scientists might soon be able to forecast volcanic eruptions by monitoring how trees respond from space. Now, in a new collaboration with the Smithsonian Institution, they have discovered that tree leaves grow lusher and greener when previously dormant volcanic carbon dioxide seeps up from the ground — an early warning that a cone of magma is pushing upwards. Now, using satellites such as Landsat 8 and data from the recent AVUELO mission, scientists think this biological response could be visible remotely, serving as an added layer of early warning for eruptions in high-risk areas that currently menace millions worldwide.

NASA Uses Tree Greening as Satellite Clue for Early Volcano Eruption Warnings in Remote Regions

As per the research by NASA’s Earth Science Division at Ames Research Centre, greening occurs when trees absorb volcanic carbon dioxide released as magma rises. These emissions precede sulfur dioxide and are harder to detect directly from orbit.

While carbon dioxide does not always appear obvious in satellite images, its downstream effects — enhanced vegetation, for example — can help reinforce existing volcanic early warning systems, notes volcanologist Florian Schwandner. It could be important because, as the U.S. Geological Survey says, the country is still one of the most volcanically active.

Globally, about 1,350 potentially active volcanoes exist, many in remote or hazardous locations. On-site gas measurement is costly and dangerous, prompting volcanologists like Robert Bogue and Nicole Guinn to explore tree-based proxies.

Guinn’s study of tree leaves around Sicily’s Mount Etna found a strong correlation between leaf colour and underground volcanic activity. Satellites such as Sentinel-2 and Terra have proven capable of capturing these subtle vegetative changes, particularly in forested volcanic areas.

To confirm this method, climate scientist Josh Fisher led NASA-Smithsonian teams in March 2025 to Panama and Costa Rica, collecting tree samples and measuring gas levels near active volcanoes. Fisher sees this interdisciplinary research as key to both volcano forecasting and understanding long-term tree response to atmospheric carbon dioxide, which will reveal future climate conditions.

The benefits of early carbon dioxide detection have been demonstrated in the 2017 eruption of Mayon volcano in the Philippines, where it allowed mass evacuations and saved more than 56,000 lives. It has its limitations, like bad terrain or too much environmental noise, but it could be a game-changer.

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Russian Researchers Discover 11 New AGNs in All-Sky X-ray Survey

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May 17, 2025

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Russian Researchers Discover 11 New AGNs in All-Sky X-ray Survey

11 new active galactic nuclei were detected in an all-sky X-ray source survey conducted by researchers from the Russian Academy of Sciences. A team led by Grigory Uskov has been on an inspection of the X-ray sources found in the ART-XC telescope of the Spektr-RG (SRG) space observatory. So far, their studies have resulted in the identification of more than 50 AGNs and several cataclysmic variables. A deeper dive into the physical properties and radiation nature of those galaxies will be crucial for a wide range of studies such as statistical insights, refining and testing cosmological models, classification studies etc.

Classification of newly found AGN

According to the recent study published in Astronomy letters, the newly discovered active galactic nuclei from the ARTSS1-5 catalog are categorised as the Seyfert galaxies, seven type 1 (Sy 1), three type 1.9 (Sy 1.9) and one type 2 (Sy 2).

AGN or active galactic nuclei are considered as the most luminous persistent sources of electromagnetic radiation in the universe. These compact regions at the centre of a galaxy are extremely energetic due to accretion onto a supermassive black hole or star formation activity at the galaxy’s center.

Based on their luminosity, AGNs are categorised as Seyfert Galaxies and Quasars. Seyfert galaxies are lower-luminosity AGNs where the host galaxy is clearly visible and emit a lot of infrared radiation, and have broad optical emission lines.

Research findings

The published paper states the 11 newly found galaxies are located relatively nearby, at redshifts of 0.028-0.258. The X-ray luminosities of these sources are within the range of 2 to 300 tredecillion erg/s, therefore typical for AGNs at the present epoch.

The spectrum of one of the new AGNs, designated SRGA J000132.9+240237, is described by a power law with a slope smaller than 0.5, which suggests a strong absorption and a significant contribution of the radiation reflected from the galaxy’s dusty torus. The authors of the paper noted that longer X-ray observations are required to determine the physical properties of this AGN.

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New Study Reveals Recent Ice Gains in Antarctica, But Long-Term Melting Continues

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22 hours ago

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May 17, 2025

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New Study Reveals Recent Ice Gains in Antarctica, But Long-Term Melting Continues

Global warming and climate change have been subjects of major concern for a long time. One of the key indicators of this phenomenon is the melting of ice in the polar regions. Researchers from Tongji University in Shanghai have been using NASA satellite data to track changes in Antarctica’s ice sheet over more than two decades. Their newest study states that despite the increase in global temperature, Antarctica has gained ice in recent years. However, it cannot be considered as a miraculous reversal in global warming because over these two decades, the overall trend is substantial ice loss. Most of the gains have been caused by unusual increased precipitation over Antarctica.

About the New study

According to the new study , NASA’s Gravity Recovery And Climate Experiment (GRACE) and GRACE Follow-On satellites have been monitoring this ice sheet since 2002. The ice sheet covering Antarctica is the largest mass of ice on Earth

The satellite data revealed that the sheet experienced a sustained period of ice loss between 2002 and 2020. The ice loss accelerated in the latter half of that period, increasing from an average loss of about 81 billion tons (74 billion metric tons) per year between 2002 and 2010, to a loss of about 157 billion tons (142 billion metric tons) between 2011 and 2020, according to the study. However, the trend then shifted.

The ice sheet gained mass from 2021 to 2023 at an average rate of about 119 billion tons (108 metric tons) per year. Four glaciers in eastern Antarctica also flipped from accelerated ice loss to significant mass gain.

General Trend in global warming

Climate change doesn’t mean that everywhere on Earth will get hotter at the same rate, so a single region will never tell the whole story of our warming world.

Historically, temperatures over much of Antarctica have remained relatively stable, particularly compared to the Arctic. Antarctica’s sea ice has also been much more stable relative to the Arctic, but that’s been changing in recent years.

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