S27E46: Stellar Cannibalism: Unraveling the Secrets of Star-Eating Phenomena

[00:00:00] This is SpaceTime Series 27 Episode 46 for broadcast on the 15th April 2024.

[00:00:08] Coming up on SpaceTime, a possible neutron star black hole merger detected in gravitational

[00:00:13] waves. A new study shows that stars often wind up eating their own planets. And the

[00:00:20] science from America's solar eclipse. All that and more coming up on SpaceTime.

[00:00:28] Welcome to SpaceTime with Stuart Gary.

[00:00:47] The LIGO-VERGA-CAGRA Gravitational Wave collaboration has detected what might be either the merger of

[00:00:53] two neutron stars, or even more excitingly that of a neutron star with a stellar mass black hole.

[00:00:59] The signal was initially detected back in May 2023, just days after the fourth LIGO-Gravity

[00:01:06] Observatory Run began. The LIGO Livingston Gravitational Wave detector observed the signal

[00:01:12] from a collision what's most likely a neutron star with a compact object between 2.5 and 4.5

[00:01:18] times the mass of the sun at a distance of roughly 450 million light years. Now unfortunately,

[00:01:24] the direction of the source could not be determined because only one gravitational wave

[00:01:28] detector LIGO Livingston was observing at the time of the signal. Neutron stars and

[00:01:34] stellar mass black holes are both compact objects, the dense remnants of massive stellar

[00:01:39] explosions. But what makes this signal cataloged as GW 230529 so intriguing is the mass of the

[00:01:47] heavier object. It falls within a possible mass gap between the most massive known neutron stars

[00:01:53] and the smallest stellar mass black holes. The trouble is the GW signal alone cannot reveal

[00:02:00] the nature of this object. Further detections of similar events, especially those accompanied

[00:02:06] by bursts of electromagnetic radiation could hold the key to solving this cosmic mystery.

[00:02:11] One of the study's authors, Jess McGiver from the University of British Columbia,

[00:02:15] says the detection reveals that there may be higher rates of similar collisions,

[00:02:20] that is between neutron stars and low mass black holes than previously thought.

[00:02:24] Before the detection of gravitational waves in 2015, the masses of stellar mass black holes

[00:02:30] were primarily found using X-ray observations while the masses of neutron stars were obtained

[00:02:35] using radio observations. The resulting measurements meant the objects fell into two

[00:02:39] distinct mass ranges with a gap between them being somewhere between 2 and 5 times the

[00:02:44] mass of our Sun. Over the years, a small number of measurements have encroached on this mass gap

[00:02:50] which remains highly debated among astrophysicists. Analysis of the signal from GW 230529 shows that

[00:02:58] it did come from the merger of two compact objects, one with a mass somewhere between 1.2

[00:03:04] and 2 times that of our Sun and the other slightly more than twice as massive. Now

[00:03:09] neutron stars are known to have masses between 1.44 and 2.3 times the mass of the Sun,

[00:03:16] 1.44 being the magic Chandra Seca limit beyond which baryonic particles can push through the

[00:03:22] electron degeneracy barrier which prevents two particles from occupying the same quantum space

[00:03:27] at the same time. And we now know that masses above somewhere around 2.3 solar masses,

[00:03:33] maybe 2.4, are thought to be capable of breaking the neutron degeneracy barrier,

[00:03:37] allowing them to crash down far enough to become black hole singularities.

[00:03:43] Now, while the gravitational wave signal doesn't provide enough information to determine with any

[00:03:47] degree of certainty whether or not the compact objects are neutron stars and black holes,

[00:03:52] it seems very likely that the lighter object is most likely a neutron star and the heavier one

[00:03:57] probably a black hole. The steady's authors are confident the heavier object is within

[00:04:02] the mass gap. Gravitational wave observations have now provided almost 200 measurements of

[00:04:08] compact object masses. Of these, only one other merger may have involved a mass gap compact object.

[00:04:16] The signal GW190814 came from the merger of a black hole with a compact object exceeding

[00:04:22] the mass of the heaviest known neutron star and possibly within the mass gap.

[00:04:28] While previous evidence of mass gap objects have been reported both in gravitational waves and

[00:04:32] electromagnetic waves, this system is especially exciting because it's the first gravitational

[00:04:37] wave detection of a mass gap object paired with a neutron star. The observations therefore

[00:04:43] have important implications both for theories of binary evolution and electromagnetic counterparts

[00:04:48] to compact object mergers. The highly successful third observation run of gravitational wave

[00:04:54] detections ended in early 2020, bringing the number of known gravitational wave detections to 90.

[00:05:00] Before the start of the fourth observing run on the 24th of May 2023, the LIGO Virgo Kagro

[00:05:05] researchers made further improvements to the detectors, the cyber infrastructure and the

[00:05:10] analysis software, allowing them to detect signals from further away and to extract

[00:05:15] more information about these extreme events which these waves generated. The current fourth

[00:05:21] observing runs plan to last a total of 20 months, including a couple of months break

[00:05:25] to carry out maintenance of the detectors and to make a number of necessary improvements.

[00:05:30] By January 16th 2024 when the commissioning break started, a total of 81 significant signal

[00:05:37] candidates had been identified and GW230529 is the first of these to be published.

[00:05:45] This space time. Still to come, a new study shows that stars often eat their own planets.

[00:05:52] And as much of the world marveled at last week's total solar eclipse to the sun across

[00:05:57] North America, scientists were busy carrying out new observations. We'll tell you what they

[00:06:02] were up to. All that and more still to come on space time.

[00:06:22] A new study has confirmed that at least one in every dozen or so stars have torn apart and

[00:06:27] consumed one of their orbiting planets. The findings reported in the journal Nature

[00:06:32] are based on a study of binary star systems which should contain two stars with an identical

[00:06:38] composition. However, in about eight percent of cases they apparently differ a finding which has

[00:06:43] been perplexing scientists. Astronomers have now found that the difference could be due to

[00:06:49] one of the stars in the group devouring planets or planetary material. The studies

[00:06:54] lead author Fan Liu from Monash University says his team were examining twin stars traveling together.

[00:07:00] They're born at the same time in the same molecular gas and dust clouds, so they should be identical.

[00:07:06] However, high precision analysis has allowed the authors to detect chemical differences between

[00:07:11] the pair. Liu says this provides strong evidence that one of the stars has swallowed

[00:07:16] either planets or planetary material and that's changed its composition. He says the same

[00:07:21] phenomenon appeared in about eight percent of the 91 pairs of twin stars the team looked at.

[00:07:27] What makes this study compelling is that the stars were all in their prime of life on the so-called

[00:07:32] main sequence rather than stars in the final phases of their existence such as red giants.

[00:07:38] Stars on the main sequence are fusing hydrogen into helium in their cores, whereas red

[00:07:43] giants are known to consume nearby planets as they expand and become bloated in the final

[00:07:48] stages of their lives. Now there is some room for doubt as to whether the stars are swallowing

[00:07:53] planets whole or whether they're simply engulfing protoplanetary material, but Liu suspects both

[00:07:59] are possible. He says it's complicated, the ingestion of the whole planet is the

[00:08:03] favorite scenario, but the team can't rule out that some of these stars are ingesting lots

[00:08:08] of material from a protoplanetary disk. The findings have been made possible thanks to a

[00:08:14] large dataset collected with the help of the 6.5-meter Magellan telescope and the European

[00:08:19] Southern Observatory's very large telescope both in Chile and the 10-meter Keck telescope in Hawaii.

[00:08:25] Liu says the research room is part of a larger collaboration known as the Complete

[00:08:29] Census of Co-Moving Pairs of Objects or C3PO, and top prizes for whoever came up with that one.

[00:08:36] It's an initiative to spectroscopically observe a complete sample of all bright co-moving

[00:08:41] stars identified by the European Space Agency's Gaia astrometric satellite.

[00:08:46] We are basically just looking at some stars which are like just like twins, so they were born together

[00:08:52] and moving around together, so we call them like co-nequal-satins. They should have been like

[00:08:57] basically identical, like have the same conversation but actually we do find some like differences

[00:09:02] in terms of their chemical composition. So from there we notice that some of those twin

[00:09:06] stars or one of them like seems to have like some higher amount of some like material and elements

[00:09:12] and that could be due to like the ingestion of pennies. So we find that to be like very interesting

[00:09:17] because it's like kind of not very commonly seen before.

[00:09:20] How common is it? How often does it happen?

[00:09:23] So it's surprising because we do know like when stars evolve to their late stage like they

[00:09:28] will tend to join four and they will eventually like weather their pennies, but like for our

[00:09:33] study we mainly thought looked at like the stars as their early or mid-stage so that they are like

[00:09:38] their main sequence stage. So in this stage it's actually uncommon because we used to believe

[00:09:43] like this kind of stellar pancreas system should be very stable just like our solar system

[00:09:48] like it's very stable and nothing like intense would happen and but actually from our study

[00:09:53] we see that it's actually happening, so at some stage like some of these like inner pennies can

[00:09:58] be just scattered into each star like due to some maybe some instability.

[00:10:02] You've got two stars they're in a binary system they're orbiting each other both stars are still

[00:10:06] on the main sequence one of them hasn't become a red giant yet or anything is that correct?

[00:10:11] Yeah so both stars are at the same stage so they are like well so they were born together

[00:10:16] so they have same age as well so they have the same they should have same compensation

[00:10:21] but then we see the difference so then from there we can see that

[00:10:25] some like planetary ingestion happened. Something's happened and if they're both of the same that

[00:10:30] means they're both at the same mass I take it if they're the same stage of evolution. Yeah yeah

[00:10:34] yeah they basically have the very same evolution of math and everything very similar.

[00:10:39] And yet when you look at these stars when you do a spectra of them you find that one

[00:10:43] star contains the sorts of elements you normally see in a planet gas or terrestrial

[00:10:49] planet I guess I should be asking? Yes yes indeed so like they are mainly like elements

[00:10:54] from like terrestrial planets actually you know like iron, nickel, silicon and aluminium so sort of

[00:10:59] like this kind of rocky material and rocky element. We'd expect to see this in a star once it moves

[00:11:06] off the main sequence it becomes a red giant or a red super giant but to see it in a

[00:11:12] in a main sequence star that's got to mean there's some sort of gravitational perturbation

[00:11:16] involving the orbit of the planet and the stars themselves. Yes yes indeed that's kind of one

[00:11:21] of the very important implication of this study so yeah it helps people to understand like the

[00:11:26] instabilities in like the stellar pantry system. I guess the next thing to do is find more examples

[00:11:32] of this. Yes yes indeed we are looking forward to like examining like more systems like this

[00:11:38] meanwhile we are also trying to for example search for like monitoring the radiovariety

[00:11:43] variation of like this system we have already identified because we know that they must have

[00:11:48] some like a perturbation there so it could be a super earth or could be a giant or something

[00:11:53] planet something like that so we're also trying to find those sort of perturbations in those systems

[00:11:59] we identified. How are you able to do the research? We have to like spend actually quite a lot of

[00:12:03] effort like to collect all of this very high quality special data they were like overtaken from

[00:12:09] like those like international like large telescopes in like Hawaii and in Chile and then we are

[00:12:15] also looking into like other like coordinate systems like for example we are looking into

[00:12:20] the our star's coordinate system because previously we don't know exactly what how many like are

[00:12:27] like really the star's coordinate systems but now we have some techniques that we can probably

[00:12:33] identify them and then apply some analysis to check if our star has some peculiar chemical

[00:12:38] composition. Our nearest neighboring star system Alpha Centauri it has two stars very similar

[00:12:43] to each other Alpha Centauri A and B we know that the third star in the group Proxima Centauri

[00:12:48] has planets we don't know yet if Alpha Centauri A and B have planets do we? We don't know for sure

[00:12:54] that's probably one which is very further away like those kind of very far away further away

[00:12:59] planning but we can't really confirm that yet. Is that a system you're going to be looking at?

[00:13:04] Yes Alpha Centauri would also be another very interesting state team to looking to yet

[00:13:08] to apply like some analysis and to compare them to for example some stars which have very similar

[00:13:15] properties of like other stars which yes they were like a bond together.

[00:13:19] That's Fan Liu from Monash University and this is space time. Still to come we look at the

[00:13:26] sort of science astronomers were up to during last week's solar eclipse and later in the

[00:13:31] science report anthropologists have discovered Australia's oldest pottery dating back to

[00:13:37] between two and three thousand years ago all that and more still to come on space time.

[00:13:58] As much of the world marveled at last week's total solar eclipse of the sun across North America

[00:14:04] scientists were busy carrying out new observations. The breathtaking displays come as the sun's nearing

[00:14:10] the peak of its 11 year solar cycle and spectators weren't disappointed with a solar corona glowing

[00:14:16] spectacularly from the moon's silhouette along the path of totality. The total solar eclipse

[00:14:23] began in the Pacific Ocean sweeping across North America after making landfall in Mexico.

[00:14:28] It then arc through the southwest, midwest and New England regions of the United States

[00:14:33] before crossing into eastern Canada and then heading out to sea from Newfoundland.

[00:14:38] Eclipse watches in Mexico got the longest period of totality when the moon completely blocks out

[00:14:44] the sun that lasted some four minutes and 28 seconds but most places along the path of totality

[00:14:51] saw durations are between three and a half and four minutes. As well as undertaking more than

[00:14:56] 40 citizen scientist projects NASA launched a small amader of rockets jets and drones to

[00:15:01] monitor the spectacle in greater detail. The agency launched no less than three Black

[00:15:07] Brant 9 sounding rockets from the Wallops Flight Facility on the Virginia-Medalantic Coast and

[00:15:12] a specially equipped drone was deployed from Fort Drum in New York State. The rockets were sent

[00:15:18] up before, during and just after the eclipse to investigate the influence of solar eclipses

[00:15:23] on the Earth's upper atmosphere including atmospheric response to the transient absence of sunlight.

[00:15:29] NASA also flew its WB-57 jets to chase the eclipse from altitudes of above 50,000 feet.

[00:15:35] That was in order to gather data for scientists wanting to better understand the solar corona

[00:15:39] and its effects on Earth. The jet's missions were designed to shed light on the current

[00:15:44] structure, its temperature and the solar wind's origins to respect parameters and cameras.

[00:15:50] They also studied the ionosphere's behavior under the shadow of the moon,

[00:15:54] potentially enhancing scientists' comprehension of the solar radiation's impact on crucial

[00:15:58] technologies like radar and GPS. But it doesn't end there. The agency also used a specially equipped

[00:16:05] drone fitted with an array of weather sensors similar to those used by the National Weather Service

[00:16:10] on daily weather balloon flights to collect data on temperature, relative humidity, pressure

[00:16:15] and winds. The aircraft was flown to its maximum altitude, nearly 3.2 kilometers in order

[00:16:21] to test an alternative data collection method from that of standard weather balloons higher in

[00:16:26] the troposphere, a lowest part of Earth's atmosphere where the weather occurs. This is Spacetime.

[00:16:38] And time out to take a brief look at some of the other stories making news in science this week

[00:16:52] with The Science Report. A new study warns that we're likely underestimating the future impact

[00:16:58] of so-called forever chemicals in the environment. A report in the journal Nature Geoscience warns

[00:17:05] that perin polyfluor alkali substances are now at levels in global water resources which far exceed

[00:17:11] safe drinking limits. These forever chemicals have been in widespread production since the 1950s

[00:17:17] and it's now thought that every human being on this planet has been contaminated by them to

[00:17:22] some degree. They've been popular because of their ability to resist heat, water, grease and

[00:17:28] stains. In fact, over 14,000 different types of chemical combinations have been developed from

[00:17:35] these perin polyfluor alkali substances. They've found their way into products ranging from some

[00:17:41] types of firefighting foams to non-stick fry pans, carpets, leather and apparel, textiles,

[00:17:47] paper and packaging, coatings, rubber, food processing and plastics. The study led

[00:17:53] by the University of New South Wales assessed the levels of forever chemical contamination

[00:17:58] in both surface and groundwater around the globe. A new study has shown that the diabetes drug

[00:18:04] somaglutide which is best known for its weight loss properties can also help reduce heart failure

[00:18:10] related symptoms and physical limitations in obese people with diabetes as well as increasing

[00:18:15] their weight loss. A report in the New England Journal of Medicine looked at around 600 diabetics

[00:18:21] with heart failure who are also obese giving them either once weekly somaglutide treatment

[00:18:26] or a placebo for a year. After 12 months, they found fewer symptoms and physical limitations

[00:18:32] in the somaglutide group and this group also reduced their body weight by around 9.8% compared to just

[00:18:38] 3.4% for those with a placebo. Anthropologists have discovered Australia's oldest pottery

[00:18:45] dating back to between 2 and 3,000 years ago. The discovery was made on Lizard Island and

[00:18:51] the Great Barrier Reef. A report in the Journal of Coordinary Science Reviews claims the findings

[00:18:56] challenged the notion that Aboriginal Australian communities were unaware of pottery manufacture

[00:19:01] before European settlement. The pottery was locally produced using local clays.

[00:19:07] The discovery sheds light on the sophisticated maritime capabilities in trading systems of

[00:19:12] First Nations communities in North Queensland connected with the pottery making communities

[00:19:16] of New Guinea. The highly prestigious Mayo Clinic has been slammed for allowing a staff nurse to

[00:19:23] promote the ranks pseudoscience of Reiki. Tim Endham from Australian Sceptic says the normally

[00:19:29] respected medical facility is being criticised by health professionals around the world for

[00:19:34] allowing the fake and unproven alternative medicine practice to be promoted under its banner.

[00:19:39] This is pretty depressing but it's not actually that unusual in a way. Mayo Clinic has

[00:19:44] of course a very prestigious medical facility in the US which generally regarded as one of the best

[00:19:49] clinical organisations in the US. It rates very, very highly often up near the top but it's not

[00:19:54] at the top and it's also very innovative in the way it sort of develops treatment and it has

[00:19:58] done since the sort of foundation 100 plus years ago. It is therefore strange and sad to see

[00:20:04] it then promoting or to have people within it promoting some very, very dodgy alternative

[00:20:10] treatment and what is even worse and something that's been pointed out is that the organisations

[00:20:14] themselves are not saying hang on. The people within sort of who are not necessarily believers in some

[00:20:19] of these treatments are not actually sort of pulling it up and they've been described by

[00:20:23] some people as shruggies like, I don't know, shrug their shoulders and saying yeah well that

[00:20:27] might be true. In particular what's happened recently is someone's putting forward supposed

[00:20:32] evidence for Reiki which is an Asian practice of moving your hands over someone's body not

[00:20:37] touching the body, not touching your feeling, is moving your hands over the body to disrupt energy

[00:20:42] flows and bad energy flows and push them away. In some cases actually it was almost literally

[00:20:47] that it's moving your hands and then pushing this energy down to the end of them and they're

[00:20:51] outside their body. It's nonsense. Okay as much as you can say anything in the medical world

[00:20:57] is pretty lacking any sort of basis at all. There might be a placebo effect, might make

[00:21:01] people feel good but this has actually supposedly been touted as scientifically proven in this

[00:21:07] information coming out of the Mayo Clinic or at least one particular researcher in the Mayo Clinic.

[00:21:12] This has been written by a nurse in the clinic named Kenneth Ruth who has sort of been promoting

[00:21:16] this particular stuff. The trouble is the energy cannot be detected, it can't be measured,

[00:21:21] it can't be confirmed in any way. There isn't an energy-based practice that's been shown

[00:21:25] to have any effect beyond placebo which is what this might be. But nonetheless from a Mayo

[00:21:29] clinic which is heavily evidence-based, heavily medical evidence, science evidence-based with

[00:21:35] innovative technologies that have been proven to work and they've been involved in a lot of

[00:21:39] different areas to have at least one person within the organization promoting pseudo-science

[00:21:44] that is totally without same direction and running off that imprimatur of the Mayo Clinic is a

[00:21:49] concern. Now it happens in lots of places you'll get rogue people. We're hearing about it

[00:21:53] with the World Health Organization too recently. The World Health Organization which is almost

[00:21:57] coming from the top there but there's also, you find within most scientific organizations

[00:22:02] there will be someone who's a loose cannon but this is someone claiming that it's scientifically

[00:22:05] proved that it's an old range of medical papers, blah blah blah, they're actually

[00:22:09] proving this thing which are not. So it's one thing to be promoting a totally unproven and

[00:22:14] disproven in some cases but you know the tenuous treatment system but then to have it coming

[00:22:19] out of such a prestigious body that's where the problem's going to concern life.

[00:22:22] If there's credibility there's something that doesn't deserve it.

[00:22:24] Absolutely and it's the extreme credibility because you know the Mayo Clinic rates very

[00:22:29] very highly amongst medical facilities in the US but the claims are just not supported

[00:22:34] and there's no indication that the practitioners who are often just trained in

[00:22:37] like it and nothing in great medical qualification it's very sad. I mean yeah the evidence has

[00:22:42] been put forward is largely anecdotal and which means that you really can't sort of study

[00:22:46] it scientifically you certainly can't prove it beyond sort of a nice feeling.

[00:22:50] That's Tim Minden from Australian Skeptics

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