Sagittarius A*’s Stellar Graveyard Reveals a Metal-Rich Black Hole Neighbourhood

[00:00:00] [SPEAKER_01] This is Space Time, Series 29, Episode 135, for broadcast on 11 November 2026. Coming up on Space Time, a stellar graveyard discovered at the heart of the Milky Way galaxy, the mystery of the origin of Earth's water, and New Zealand's rocket lab to start flying from Alaska. All that and more coming up on Space Time.

[00:00:25] [SPEAKER_00] Welcome to Space Time with Stuart Gary.

[00:00:44] [SPEAKER_01] A new study has shown that gas orbiting the black hole at the center of our galaxy is rich in metals from the corpses of dead and dying stars. The findings reported in the Astronomical Journal show that this gas is similar in composition to many of the stars in the black hole's orbit, suggesting the gas and stars form together. The supermassive black hole at the center of our Milky Way galaxy, Sagittarius A star,

[00:01:09] [SPEAKER_01] is located some 27,000 light years away and contains 4.3 million times the mass of our Sun. The Sagittarius A star is closer to Earth and therefore easier to see and study than any other supermassive black hole. So the new findings could advance science's understanding of how metals are distributed around supermassive black holes in more distant galaxies, as well as the processes that supplied Earth

[00:01:33] [SPEAKER_01] with many of these elements. In astronomy, metals include any element heavier than helium and hydrogen. And their presence influences how quickly gas is cool, which in turn influences how readily the gas can be drawn into a black hole. The study's lead author Nicole Ford from McGill University says astronomers know there's a black hole at the center of our galaxy pulling material into itself, but it's eating a lot less material than other supermassive black holes and it's doing so much

[00:02:03] [SPEAKER_01] more slowly. Part of understanding why this is happening means looking at the properties of the materials available for it to consume, including gas, dust and the stars orbiting around it. So to work out what's going on, Ford and colleagues used data gathered by NASA's Webb Space Telescope. Webb measures infrared light over a wide range of wavelengths with unprecedented spectral and spatial resolution, and that allows astronomers to distinguish the heat signatures of multiple

[00:02:30] [SPEAKER_01] gas clouds orbiting near the black hole. It also enabled them to precisely measure the metal composition of each gas cloud. The new findings complement a recent study which tested whether gas preserved the evidence of previous bursts of energy coming from Sagittarius A-star. The results found that the gas emission was shaped by local conditions, making it difficult to isolate the black hole's influence. Rather than ruling out past outbursts, this shows that the

[00:02:57] [SPEAKER_01] surrounding gas cannot provide a reliable history of the black hole's activity. Ford says understanding how the black hole attracts material will therefore require comparing these observations with simulations of how gas evolves over longer timescales. This space-time. Still to come. The mystery of the origin of Earth's life-giving water supplies. And New Zealand's rocket lab, about to start launching from Alaska. All that and more

[00:03:25] [SPEAKER_01] still to come, on space-time. A new study suggests planet Earth may have formed much of its water during its time. The solar system's formation in the protoplanetary disk rather than later from asteroid or cometary impacts as often speculated. The solar system's planets, including the Earth, were created by

[00:03:51] [SPEAKER_01] condensing out of a disk of spinning gas and dust called a protoplanetary disk orbiting around the then still nascent Sun. Over time, these dust grains clumped together through static electricity, and later gravity, accreting to form protoplanets and eventually planets. Different elements and different materials condensed at different distances from the protoplanetary sun, depending on temperature. Iron condenses closest to the sun, silicon a bit further away, and the ices such as water and

[00:04:20] [SPEAKER_01] methane and ammonia further out still beyond what's known as the snow line, which lies between the orbits of Mars and Jupiter. So how planet Earth got its water, essential for life as we know it, has always been a mystery. Now a new study reported in the journal Nature Geoscience suggests Earth may have produced its own water during its formation as rocky pebbles reacted with a hydrogen-rich atmosphere surrounding the young planet. These new findings offer a potential explanation for how Earth acquired

[00:04:49] [SPEAKER_01] one of the essential ingredients for life, and they suggest that similar water-producing processes may have been common on the rocky planets throughout the inner solar system. The study used high-temperature experiments to investigate how iron-bearing silicate rocks react with atmospheric hydrogen under conditions similar to those found during the early stages of planetary formation. One of the study's authors, Zachary Sharp from the University of New Mexico, says previous ideas about the source of water on Earth

[00:05:18] [SPEAKER_01] relied on an external source, such as comets or meteors, from colder regions in the early solar system. However, the problem is that hydrogen-to-deuterium ratios in comets and meteorites don't match those found in Earth's oceans. And that means another source. The new work shows that virtually any Earth-sized planet could have water by this newly identified mechanism. Sharp says in order to evaluate the possibility of pebble rain being the source of water, the authors needed to construct and execute

[00:05:47] [SPEAKER_01] some very challenging experiments, showing that water is produced in just minutes in very high-temperature environments such as the early Earth's atmosphere. As Earth formed, small rocky particles, known as pebbles, accumulated to build a larger planetary body, a process called pebble accretion. When the growing planet becomes sufficiently massive, it could develop a hot, high-pressure atmosphere rich in hydrogen. As the silicate pebbles fell through this atmosphere,

[00:06:13] [SPEAKER_01] iron oxide in the rocks could react with hydrogen, producing metallic iron and water vapor. Now to test this process, the authors heated silicate rock samples at temperatures between 1200 and 1400 degrees Celsius in streams of hydrogen, and for comparison, helium. The experiments lasted between 15 minutes and 3 hours. In the hydrogen experiments, nearly 80% of the iron oxide in the samples was

[00:06:38] [SPEAKER_01] converted into metallic hydrogen, producing water vapor as a by-product in the process. But the same reaction didn't occur in the helium experiments, demonstrating the importance of hydrogen in the water producing process. And the authors were surprised how quickly water was produced and how large the quantities were. The study provides new insights into the chemical processes that shape the early Earth and expand science's understanding of the possible pathways through which water can

[00:07:05] [SPEAKER_01] develop on rocky planets. Water is Earth's most valuable resource, so knowing its origins and its hydrology

[00:07:13] [SPEAKER_02] is important. This report from Massey TV. Water is the fundamental ingredient for life on Earth. Looking at our Earth from space, with its vast and deep ocean, it appears as though there is an abundance of water for our use. However, only a small portion of Earth's water is accessible for our needs. How much fresh water exists, and where it is stored, affects us all.

[00:07:40] [SPEAKER_02] Nearly two-thirds of this fresh water is stored in the polar ice caps, snow packs, and glaciers, making it inaccessible for long periods of time. The water cycle is dynamic. It describes the continuous movement of water on, above, and below the surface of the Earth, and the transitions from one state to another.

[00:08:04] [SPEAKER_02] The water cycle is a very similar. Sea surface temperature, surface winds, and air temperature influence the rate of evaporation at the ocean surface. In the tropics, warm ocean surface temperatures support high rates of evaporation. Wind also increases evaporation. When the air's temperature is warmer, it can hold more water.

[00:08:27] [SPEAKER_02] While the atmosphere does not store a large quantity of water compared to the ocean, rivers, and lakes, it can transport water quickly from one place to another. Low-lying regions of the atmosphere with high moisture and strong winds can form atmospheric rivers to transport water horizontally. Clouds are formed as water vapor cools and condenses into droplets and ice crystals. Clouds and water vapor act as insulators in the atmosphere.

[00:08:57] [SPEAKER_02] Clouds help shield the Earth from the sun and trap heat from below. When cloud particles grow large enough, they may fall out as rain or snow. Under the right conditions, areas of precipitation can grow into large storms. As storms grow, they transfer heat vertically into the upper atmosphere. The migration of storms helps to distribute heat between the equator and poles, shaping wind patterns globally.

[00:09:27] [SPEAKER_02] How storms grow and intensify depends on atmospheric moisture, surface temperatures, and wind patterns. Precipitation is concentrated in some parts of the world and scarce in others. It can vary substantially from season to season and from year to year. Water that falls on the land surface as precipitation is stored within snow packs, lakes, reservoirs, soils, and underground aquifers.

[00:09:56] [SPEAKER_02] Water availability varies from place to place and over time. Water is a very important part of the water. The availability of water affects the type and abundance of vegetation, the primary source of food for animals and people. Extreme water cycle variability, unusually dry or wet conditions, impacts humans worldwide. Each year, hazards such as floods exact a costly, economic, and human toll.

[00:10:23] [SPEAKER_02] Most of the water that falls onto land remains stored there for weeks or more. Water is stored as snowpack or ice. Meltwater and rainfall are stored in lakes and soils. Some of the water is absorbed by plant roots or drains into the water table. Eventually, the water will evaporate to the atmosphere or return to the ocean and streams and rivers, providing a source of nutrient-rich water that supports ocean life.

[00:10:51] [SPEAKER_02] Sensors on a suite of NASA satellites observe and measure water on land, in the ocean, and in the atmosphere. These measurements are important to understanding the availability and distribution of Earth's water, which is both vital to life and vulnerable to the impacts of climate change and a growing world population.

[00:11:13] [SPEAKER_01] This is space time. Still to come, New Zealand's rocket lab to begin flying from Alaska. And later in the science report, a new study shows a derivative of vitamin B5 used as a cholesterol-lowering supplement can also stop psoriasis. All that and more still to come on Space Time.

[00:11:47] [SPEAKER_01] New Zealand's rocket lab is building two new launch pads in Alaska. The new facilities will expand the company's ability to conduct rapid response launches and missile defense testing for the United States military. The facilities are planned for the Pacific Spaceport Complex on Kodiak Island, where the company's first launch pad is expected to be operational by January. The launch complex will support Rocket Lab's Electron and Hasty rockets, and will use the company's new Ghost transportable containerized launch system.

[00:12:17] [SPEAKER_01] Ghost packages complete rockets, launch infrastructure, ground support equipment, and range control systems inside standard shipping containers. Rocket Lab previously secured a $266 million US Space Force contract covering 12 suborbital launches, with options for a further six. The Alaska site will give the company additional flexibility to conduct national security missions alongside its existing operations in Virginia and New Zealand.

[00:12:45] [SPEAKER_01] Rocket Lab currently operates two launch pads at its Mahaya Peninsula Launch Complex at Hawke's Bay on New Zealand's North Island East Coast. These are designed to launch its two-stage Electron rocket, which is capable of carrying payloads and small satellites up to 300 kilograms into low Earth orbit. The company operates a third launch pad for Electron orbital missions, as well as Hasty suborbital rockets at NASA's Wallops Island Flight Facility on the Virginian Mid-Atlantic coast.

[00:13:12] [SPEAKER_01] Hasty is a modified variant of Electron designed to carry payloads of up to 700 kilograms on suborbital missions. The company is currently building a second launch pad at Wallops Island for its new reusable Neutron rocket, which will be capable of carrying payloads of up to 13 tons into low Earth orbit. Neutron's maiden flight is slated for next year, and needless to say, we'll keep you informed. This is Space Time.

[00:13:39] [SPEAKER_01] And time now to take another brief look at some of the other stories making news in science this week, with a science report. Scientists say a derivative of vitamin B5 called patathene, widely used as a cholesterol-lowering supplement,

[00:14:07] [SPEAKER_01] has been shown to stop psoriasis, alleviating symptoms and limiting the activity of the immune cells behind the condition. The findings, reported in the Journal of Experimental Medicine, looked at dendritic cells, which are specialised immune cells thought to underlie a variety of autoimmune diseases, including psoriasis. The authors found cells in psoriasis patients had elevated levels of enzymes called vanines, which lowered the levels of pantathene, leading to higher cholesterol production and hyperactivation of the cells.

[00:14:36] [SPEAKER_01] Adding pantathene reversed this process, stopping psoriasis from developing. The authors tested patathene in 24 psoriasis patients, half of whom were given the supplements in addition to normal care. They found that patients given the supplements showed improved symptoms compared to those on normal care alone, especially if they had elevated blood cholesterol levels to begin with.

[00:14:58] [SPEAKER_01] A study of nearly a million married couples in Taiwan has found that having a spouse with dementia may put you at greater risk of also developing the condition. The findings, reported in the Journal of the American Medical Association, showed that the female spouses of people with dementia had a 74% higher risk of dementia, or male spouses had a 69% higher risk.

[00:15:20] [SPEAKER_01] The authors also found the risk was lower among people with higher incomes or more children, suggesting financial resources and family context may play a role. Scientists say Northern Australia is a lifeboat for the critically endangered green sawfish. A report in the Journal's Reviews in Fish Biology and Fisheries Aims and Scope examined decades of research on the rare species,

[00:15:43] [SPEAKER_01] showing that the northern Australian coast, especially around the W.A.'s Pilbara region, could be playing a crucial role in the species recovery. Green sawfish, distinguished by their long shark-like body and tooth-lined saw on the front of their heads, are on the verge of extinction, largely due to overfishing and habitat loss. Green sawfish, distinguished by their young children, and the young children, and the young children, A new study has shown that using a smartphone after 10pm is linked to teens falling asleep later, waking up later, and sleeping less.

[00:16:12] [SPEAKER_01] The findings, reported in the Journal of the American Medical Association, used Fitbit data on 425 teens, measuring their evening phone activity and when and how long they slept. The authors found that using a phone in the final minutes before bed was linked to teens waking up more often after falling asleep, mostly during the first 30 minutes after nodding off. They say this wakefulness after falling asleep was triggered most by cell phone use in the final five minutes,

[00:16:39] [SPEAKER_01] and became negligible if the kids put down their phones 20 minutes before going to bed. Australia's largest telco has been forced to apologise after a yet-to-be-explained technical glitch from its message bank system, which sent out thousands of phantom missed calls and voicemail notifications. Because the system error queued up and then released years of severely delayed notifications all at once, some customers shockingly received text alerts appearing to come from deceased relatives and loved ones,

[00:17:08] [SPEAKER_01] a message from the dead. With the details, we're joined by technology editor Alex Zaharov-Reutt of Royt from TechAdvice.life.

[00:17:16] [SPEAKER_00] Well, look, your phone wasn't planted, telco's voicemail system just cleared its throat all at once. There was some sort of glitching message bank which was sending people text messages. There were no calls made, there were no messages sent, but this was previous messages that were sent, people in the family group, and look, it's just one of those weird things where people were getting messages, including reportedly from the relative who had passed away. Telco hasn't published a detailed call. It did have an apology. We're sorry for how confusing this must be.

[00:17:45] [SPEAKER_00] It is funny that it happened just after Halloween, but... Now, luckily there was a queue of notifications backed up somehow, they got released all at once and some alerts were for calls never made, which also suggests that some of the records were scrambled. So it's a bit of a question for Telco as to what is going on there, you know, what else is playing up that we don't know about. How often does this sort of thing happen? But look, it's a glitch. It's one of those things.

[00:18:06] [SPEAKER_01] Of course, the other big news right around the world has been the blue wave, which has washed over the United States. What's that done to the stock market, especially when it comes to tech stocks?

[00:18:16] [SPEAKER_00] Well, I mean, this route wiped that roughly 2.5 trillion in market value. And this is on fears that Democrat midterm gains could slow the AI build out. Chip makers were hard. I mean, the NASDAQ was down 5.5 percent. The S&P 500, 4.36 percent. The Dow, 3.4.4. All three had their worst day since April 2025. And the NASDAQ is now officially in a correction. The chip makers, NVIDIA, which is massively successful, that's October 9 percent.

[00:18:44] [SPEAKER_00] The Philadelphia Semiconductor Index, the plumage, 12 percent. Micron and AMD fell 17 percent each.

[00:18:49] [SPEAKER_01] That's Alex Zaharov-Reutt from techadvice.life. And this is Space Time. And that's the show for now. Space Time is available every Monday, Wednesday and Friday through

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[00:19:56] [SPEAKER_00] You've been listening to Space Time with Stuart Gary. This has been another quality podcast production from Bytes.com.