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Hubble and Gaia Uncover Evidence of Ancient Dwarf Galaxy Devoured by the Early Milky Way

Hubble and Gaia reveal evidence of an ancient Milky Way merger with a dwarf galaxy about 11.8 billion years ago, reshaping our understanding of the galaxy’s origins.

Sebin Pious

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Artist’s concept of an ancient Milky Way merger with the LKH dwarf galaxy
An artist's concept of the ancient merger between the dwarf galaxy LKH and the young Milky Way about 12 billion years ago. Hubble observations of ancient globular star clusters provided evidence for the long-ago collision. Image credit: NASA, ESA, Joseph Olmsted (STScI)

A Milky Way merger with a dwarf galaxy about 11.8 billion years ago has been uncovered by astronomers using the Hubble Space Telescope and ESA’s Gaia mission. The discovery provides new evidence about how the Milky Way formed and identifies a distinct population of ancient globular clusters linked to the merger.

Our home galaxy, the Milky Way, contains hundreds of billions of stars today. It grew to this size over billions of years by pulling in smaller neighbouring galaxies and absorbing them. Now, astronomers using the NASA/ESA Hubble Space Telescope and ESA’s Gaia mission have found evidence of a major merger that occurred near the very beginning of the Milky Way’s history.

By combining precise stellar age and chemical-composition measurements from Hubble with motion-mapping data from Gaia, the team pushed back the known timeline of the Milky Way’s formation by roughly 1.8 billion years. The findings, led by Davide Massari of the Astrophysics and Space Science Observatory of Bologna, Italy, were published this week in Nature Astronomy.

Evidence of an Ancient Milky Way Merger

Reconstructing the Milky Way’s earliest history is difficult: in its youth, the galaxy was smaller, more chaotic, and closer in size to the dwarf galaxies it collided with, and many physical traces of those early mergers have since been erased.

To work around this, the researchers studied 39 globular clusters — dense, ancient groupings of up to a few million stars — in the inner 20,000 light-years of the galaxy, where evidence of the earliest mergers is most likely to survive. Using Hubble’s high-resolution imaging, the team measured each cluster’s age and metallicity (its abundance of elements heavier than helium) with what the researchers describe as unprecedented precision.

“Thanks to the high resolution and depth of Hubble imaging, we could measure the age and the metal content of these clusters with unprecedented precision,” said Chiara Zerbinati, a co-author on the study at the University of Bologna, in a release issued by ESA Hubble. “Coupled with measurements from Gaia, this made it possible to distinguish a population of globular clusters that are different from the others.”

Identifying LKH

Cross-referencing Hubble’s age and metallicity data with Gaia’s motion measurements, the researchers identified a distinct third population of globular clusters — older than the ones known to have arrived during the Milky Way’s collision with the Gaia-Sausage-Enceladus dwarf galaxy about 10 billion years ago, but younger than the stars that formed within the Milky Way itself.

That pattern pointed to a separate, earlier merger: the absorption of a dwarf galaxy roughly 11.8 billion years ago — about two billion years after the Big Bang — carrying a total stellar mass of around 500 million times the mass of the Sun, a significant share of the Milky Way’s total mass at the time.

The researchers named the dwarf galaxy Low-energy-Kraken-Heracles, or LKH, after three earlier papers that had proposed the idea of an early merger in the Milky Way’s history.

“Our home is the Milky Way galaxy, but we do not know how our house was built,” Massari said. “In this paper we discover where the first significant batch of bricks came from: a dwarf galaxy that we call LKH.”

Rewriting Early Galactic History

The finding challenges an earlier assumption that the Milky Way’s oldest stellar populations formed almost entirely in place, showing instead that external galaxies contributed to its structure far earlier than previously established.

The team plans to extend the analysis to additional globular clusters across the galaxy, aiming to build a more complete map of the mergers that shaped the Milky Way over cosmic history.

Sebin Pious is a management professional, business consultant, and independent content contributor based in the Netherlands. He works with startups and growing organizations on business strategy, marketing, and execution. His areas of interest include international relations, politics, economics, history, and current affairs.

Space & Physics

JWST Finds Water Around a Dying Star Near the Milky Way’s Black Hole

A dying star near the Milky Way’s central black hole is shedding water, gas and dust into one of the galaxy’s most extreme environments.

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JWST infrared view of the densely populated region around the Milky Way’s central black hole, filled with stars, glowing gas and dust.
A dense field of stars, gas and dust surrounds the centre of the Milky Way in this infrared view from the James Webb Space Telescope. The region includes the environment around Sagittarius A* and nearby stars such as IRS 3. Image credit: ESA/Webb, NASA & CSA, F. Peißker, J. Lu, F. Yusef-Zadeh, N. B. Sabha, C. Chan

A dying star nearing the end of its life is shedding material into space just 0.55 light-years from the Milky Way’s central black hole. And somehow, some of that material is holding on. New observations from the James Webb Space Telescope have revealed water and oxygen-rich dust surrounding IRS 3, an evolved star living remarkably close to Sagittarius A*, the supermassive black hole at the heart of our galaxy.

The finding gives astronomers a rare view of what happens when an ordinary stage of stellar evolution unfolds in an anything-but-ordinary neighbourhood.

A Dying Star Beside a Black Hole

IRS 3 is an asymptotic giant branch (AGB) star, a late stage in the life of stars like this one. As such stars age, they swell, cool and lose material through powerful stellar winds. IRS 3 is doing exactly that. Gas and dust are streaming away from the star, creating a large envelope around it.

The star sits only about 0.55 light-years from Sagittarius A*. That may sound distant, but on the scale of the Galactic Centre it is remarkably close. Earth is about 26,000 light-years away from the same black hole.

Multi-panel views zooming from the Milky Way’s centre to dying star IRS 3 and Sagittarius A*, comparing visible and infrared observations including JWST’s detailed view.
A series of observations zooms from the Milky Way’s central region to IRS 3, the dying star located about 0.55 light-years from Sagittarius A*. The JWST infrared view reveals the crowded environment around the star and the Milky Way’s central black hole. Image credit: ESA/Webb, NASA & CSA, F. Peißker, J. Lu, F. Yusef-Zadeh, N. B. Sabha, C. Chan

Around Sagittarius A* is a crowded, energetic environment filled with intense radiation, dense gas and powerful gravitational forces. Astronomers have long wondered how stars manage to evolve and shed material there. IRS 3 is offering an answer.

Webb Finds Water in the Stellar Outflow

NASA‘s James Webb Space Telescope looked at IRS 3 using its Mid-Infrared Instrument, or MIRI. Infrared observations are particularly useful here because the dust surrounding the star glows strongly at these wavelengths.

The observations revealed oxygen-rich dust in the star’s envelope. They also produced the first detection of water in this material. This does not mean Webb found a pool, cloud or droplets of water. The water exists as molecules mixed into the hot gas and dust surrounding the star.

That distinction matters because molecules can be vulnerable in the harsh environment around the Galactic Centre. Radiation can break them apart, while the conditions around a supermassive black hole can affect the material being expelled by nearby stars. Yet water molecules are present around IRS 3.

The Star is Feeding Its Surroundings

IRS 3 is losing material rapidly as it approaches the end of its life. Researchers estimate that the star is shedding roughly the mass of Earth every 18 days. That enormous outflow is important beyond IRS 3 itself.

When evolved stars lose their outer layers, they return material to the space between stars. The gas carries elements produced during the star’s lifetime, while newly formed dust becomes part of the reservoir from which future cosmic structures can emerge. IRS 3 is therefore caught in a familiar cycle of stellar life: a star is dying, but the material it releases can become part of something else.

What makes this case unusual is that the recycling process is happening almost next door to a supermassive black hole.

How Much Can Survive Here?

The observation does not mean that the black hole has little influence on its surroundings. Sagittarius A* still creates an extreme environment, and the researchers are interested precisely because IRS 3 shows that stellar material can persist within it.

“Galactic centres are among the most extreme environments,” said Florian Peißker of the University of Cologne, the study’s lead author to media. With Webb, researchers can now examine the material around stars such as IRS 3 in much greater detail and ask how stellar winds, dust formation and molecular chemistry behave so close to a black hole. The answer emerging from IRS 3 is intriguing: the environment may be extreme, but it does not necessarily shut down the chemistry of a dying star.

For IRS 3, the end of its stellar life is already underway. Its outer layers are drifting away into the Galactic Centre, carrying dust, molecules and the chemical ingredients of future cosmic systems with them. Even in the shadow of the Milky Way’s central black hole, a dying star is still leaving something behind.

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Space & Physics

India’s New Satellite Will Be Tested During Disasters

India’s latest Earth-observation satellite, EOS-05, could give disaster agencies a broader and more frequent view of floods, landslides and other hazards. But its real value will depend on how quickly satellite data can be turned into information that helps authorities act on the ground.

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GSLV-F17 rocket carrying ISRO’s EOS-05 Earth-observation satellite at the launch pad
ISRO’s GSLV-F17 carrying the EOS-05 Earth-observation satellite stands ready for launch, marking India’s first imaging satellite mission to geosynchronous orbit. Image credit: ISRO

When a flood spreads or a landslide cuts off a village, one of the first things authorities need is a clear picture of what has happened. India’s newest Earth-observation satellite could help close part of that information gap. Which areas are under water? Which roads are still open? Where are people stranded? Ground teams may be unable to reach affected areas, while conditions can change faster than assessments can be completed.

On September 4, the Indian Space Research Organisation (ISRO) successfully launched GSLV-F17 carrying EOS-05, which ISRO describes as India’s first imaging satellite designed for geosynchronous orbit. The satellite was placed into a sub-geosynchronous transfer orbit before its subsequent orbital operations.

The launch is a technological milestone. But its larger significance may be in how India uses the satellite once it is in operation.

Seeing a Disaster From Above

Earth-observation data already play a role in India’s disaster management. ISRO’s systems are used for applications including flood mapping, damage assessment and emergency management, while the National Database for Emergency Management brings together geospatial information for disaster agencies.

EOS-05 adds a different capability because of its orbit. A geosynchronous satellite can repeatedly observe a broad region as the Earth rotates. That makes it possible to monitor large areas without relying entirely on a satellite making another pass over the location.

During a flood, that could help authorities understand the extent of inundation. After a landslide, imagery could contribute to assessing affected terrain. The same Earth-observation infrastructure has applications in agriculture, water resources, forestry and urban planning. But the satellite itself is not the solution.

The Real Test is Speed

There is a long distance between an image captured in space and a decision made in a district control room. Data have to be received, processed and interpreted. The resulting information has to reach officials and emergency teams quickly enough to matter. That is particularly important when disasters are unfolding by the hour.

A satellite cannot rescue people or reopen a blocked road. What it can do is help authorities decide where those efforts are most urgently needed.

That distinction is important. The value of space technology in disaster management is not simply that it produces better images. It is that those images can potentially reduce the time needed to understand what is happening on the ground.

From Mapping Damage to Managing Risk

India’s disaster landscape makes that capability increasingly relevant. Floods can spread across districts, while landslides can isolate mountain communities with little warning. Cyclones, forest fires and extreme rainfall can also leave authorities trying to assess large areas at once.

Satellite observation cannot predict every such event. But combined with weather forecasts, river-level data, ground reports and geographic information, it can provide a fuller picture of how a disaster is unfolding. That is where EOS-05 could become more than another addition to India’s satellite fleet.

The real measure of its success will not be the launch itself, or even the quality of the images it produces. It will be whether those images reach the right people quickly enough to change what happens on the ground. Because in a disaster, seeing more is useful only if it helps authorities act faster and act in the right place.

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India’s Moonshot Moment: Can New Delhi Turn Orbit Into Influence

India’s space mission is entering a new era, from Gaganyaan and space stations to private startups, space diplomacy and national security.

Anoop Krishnan H

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Gaganyaan is only the beginning. India’s space mission faces new opportunities and challenges as human spaceflight
The Gaganyaan capsule, illustrated: India's answer to six decades of human spaceflight by other powers. Illustration: Edpublica

Gaganyaan is only the beginning. India’s space mission faces new opportunities and challenges as human spaceflight, diplomacy, private industry and security reshape its ambitions beyond Earth.

Indian human space programme Gaganyaan is mooted by Indian Space Research Organisation. This ambitious space mission aims to send Indian astronauts in Outer Space indigenously by the proactive leadership of the Indian government.  India as a leading space power of the world aims to demonstrate her space capabilities and research in the final frontier. The Gaganyaan mission is the dream of 1.4 billion Indians. The programme will be initiated in 2027 creating a historic mark in the collective space exploration journeys. This is a stepping stone as NASA is envisioning to make Moon as the next base for active space programmes by 2030.

According to NASA this spectacular feat will be achieved soon within 3 years.  NASA has asked India’s ISRO to join for the permanent Lunar base in the south pole of Moon. Here comes the significance of Indo-US space partnership and how India will navigate through the space diplomacy keeping in mind of Indian dream of Bharatiya Antariksh Station and the long lasting commitment to strategic autonomy and an independent foreign policy. India already signed the Artemis accords in June 2023. If India is ready to be part of this initiative, it will mark the beginning of a new era in India-United States space cooperation. The question is how India will navigate this process, protecting its sovereignty and national interest while engaging with NASA to help build a new civilisation of space travellers on the lunar surface. According to media reports  India’s spectacular success with the Chandrayaan missions has led the United States to choose India as a natural partner, inviting it to join space exploration programmes on the Moon.

India’s Space Mission: The Next Frontier of Global Power

india space milestones timeline 2
Tracing India’s human spaceflight and space-policy milestones from Rakesh Sharma in 1984 through to the planned Gaganyaan (2027) and Bharatiya Antariksh Station (2035) — achieved milestones in blue, planned ones in amber.

The Gaganyaan mission is significant for strengthening Indian space station’s vision.  The Bharatiya Antariksh Station is an Indian space station which is a symbol of Indian space nationalism and a centre for joint research with friendly nations. India is actively pushing for space diplomacy and it is evident from the trainings received by Gaganyaan crew members. They have trained in Russia and the United States, continuing India’s commitment to strong bilateral ties with both Cold War-era rivals. Space exploration and travel are combined with diplomacy, as Indian foreign policy in a multipolar world order pushes for strong partnerships with both Russia and the United States.

Indian Air Force veteran Wing Commander Rakesh Sharma was the first Indian cosmonaut to reach the final frontier, in a Soviet space mission. Following this historic feat, Kalpana Chawla and Sunita Williams travelled to outer space on American missions. Recently, Group Captain Shubhanshu Shukla represented India in the Axiom mission successfully travelling to International Space Station and returned safely as a national hero. He is also part of the Gaganyaan mission. Colonel Anil Menon, who is part of the US Space Force, is also now in outer space. He has strong Indian connections, making him the first astronaut with roots in Kerala to explore the domain of outer space.

With privatisation in outer space in India, Skyroot Aerospace, a private company based in Hyderabad, successfully launched Vikram-1 rocket to low Earth orbit. Thus India is taking leverage of the infinite possibilities chasing stars and galaxies. Indian space ambitions are at a historic juncture now, with over 400 private Space  startups. Another mission is aiming for a reusable re-entry vehicle, targeted for launch in 2027, building on ISRO’s success with the Pushpak mission, the Reusable Launch Vehicle Landing Experiment, in 2024.

India's space mission. Gaganyaan crew module mounted on the test vehicle during ISRO's TV-D1 mission preparations.
Gaganyaan crew module and test vehicle used for ISRO’s TV-D1 abort test mission in 2023. Image Credit: Indian Space Research Organisation (ISRO), Government of India

However, there are concerns in India’s space sector, with many ISRO scientists seeking early retirement. The efficiency of major projects like Aditya and Gaganyaan should not be affected by this. Former ISRO Chairman G Madhavan Nair shared his concerns with the media about bureaucratisation within the organisation. ISRO is a symbol of India’s space story which is filled with resilience and strength of great visionary leaders like Dr Vikram Sarabhai and Dr APJ Abdul Kalam. Unfortunately, there have been budgetary cuts to major ISRO space projects. The government’s focus on Viksit Bharat, a holistically developed India, is only possible with investment in science and technology, and in-depth research in the domain of outer space.

Outer space is militarised, and the race for resource nationalism is a reality. For India to emerge as a global power, investment in space exploration is inevitable. Nations are increasingly aware of the strategic use of outer space for securing national interests. Satellites with civilian and national security purposes are critical assets of any nation. India too has many civilian and strategic assets in outer space, and protecting these is the responsibility of the government. The anti-satellite test Mission Shakti is a milestone demonstrating India’s hard-power capabilities in outer space. Some nations have capabilities such as laser-guided weapons, which can disable or destroy an enemy’s assets during conflict. Space is a key domain for ensuring seamless communication and intelligence-sharing during both war and peace.

Intelligence and surveillance are key factors in winning the wars of the present and future. The dominance in space technology and information superiority will determine the victories of nations fighting for their national interest.   

In India, the share of higher education in the annual budgetary allocation remains low. A young generation passionate to explore arenas of space science is to be inculcated with the right mindset. Allocation of funds in education sector is a key requirement for building a strong India with educated and skilled youth. ISRO’s active collaboration with 100 Atal Tinkering Labs is a positive step in inculcating the spirit of scientific enquiry at the grassroots level. Support and encouragement for students in the creative arts and sciences is the need of the hour. Atal Tinkering Labs and India’s startup ecosystem can achieve greater synergy, ensuring a seamless transition from school life to entrepreneurship, from plan to execution.

Human activity has actively degraded the ecosystem, impacting life on both land and water. Now, with active competition in the arena of outer space, space debris is a serious global security challenge. This debris travels swiftly in outer space, damaging active space assets including civilian and defence satellites. The young budding scientists of India need to re-invent and discover practical solutions to the pressing global challenge of space debris and work with relentless passion for making a strong and stable India.

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