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'Vampire' neutron star blasts are related to jets traveling at near-light speeds

Aneutron star is the remains of a massive star that once died in a supernova explosion. As a whole, neutron stars are considered some of the most extreme objects in the known universe — and that's especially true when these incredibly dense star remnants exist alongside companion stars (that haven't yet "died") close enough for a neutron star's immense gravity to strip away material from that second star. In other words, the companion star is like the neutron star's stellar victim.

Tese "vampire neutron stars" are special because they spring back to life like a cosmic Bela Lugosi. This is because a companion star's infalling material triggers thermonuclear explosions at the neutron star's surface. Some of this stolen matter is channeled toward the poles of the neutron star, from where it erupts at near-light speeds in the form of powerful astrophysical jets. Yet quite what causes these jets to be launched — and how they connect to these thermonuclear bursts — has remained a mystery. 

New research, however, has offered a lead in the puzzle. 

Scientists have revealed one way to measure the speeds of those jets and connect the values to the qualities of both a neutron star and the unfortunate binary companion star it feasts on. This could ultimately help resolve this jet-related dilemma, and perhaps offer information about other objects that strip matter from a companion star too, such as supermassive black holes. 

"For the first time, we have been able to measure the speeds of the steady jets that are launched from a neutron star," lead author and National Institute for Astrophysics (INAF) scientist Thomas Russell told Space.com. "These jets, like those from accreting black holes, are an incredibly important in our universe, as they impart huge amounts of energy into their surroundings, affecting star formation, galaxy growth, and even how galaxies cluster together. But we don't really understand how these jets are launched."

Russell explained that, previously, scientists had thought the jets could be launched either due to the rotation of material stripped from a victim star as that material spirals in. There was also the theory that the jets are connected to the spin of the rotating object itself. 

This new research could help pin down an answer about which mechanism is predominantly responsible.

"Our discovery of a connection between the thermonuclear explosions and the jets now offers us an easily accessible and repeatable probe to disentangle the launching mechanism of the jets in neutron stars," Russell continued. "As we think jets are launched in very similar ways for all types of objects, this will help us understand how the jets are launched from all objects, even the supermassive black holes that reside at the centers of galaxies."

How do neutron stars blow their top?

To reach their conclusion, Russell and colleagues examined two systems containing feeding neutron stars: The X-ray binaries 4U 1728-34 and 4U 1636-536. Both systems are known to periodically erupt with thermonuclear bursts.

Thermonuclear explosions on the surfaces of neutron stars are not a new phenomenon for scientists. These explosions have been analyzed for years, and Russell points out that astronomers have observed at least 125 "bursting" neutron stars in total. 

"As the neutron star consumes matter from a nearby star, the accreted material builds up on the surface of the neutron star," Russell said "At some point, the pressure becomes too great, and an unstable, runaway thermonuclear explosion occurs that spreads across the whole surface of the neutron star in a matter of seconds." 

Bursts associated with 4U 1728-34 and 4U 1636-536 are visible in the X-ray band, meaning the team was able to use the European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) space telescope to detect them.

"We found that these explosions cause some extra material to be pumped into the jets for the tens of seconds that the bursts last," Russell continued. "Using radio telescopes to monitor the jets with the Australia Telescope Compact Array, we were able to track this extra material as it flowed down the jets, basically providing us with a cosmic speed camera to measure the jet speed."

 

An illustration of the INTEGRAL space telescope which was integral to determining the speed of jets from neutron stars. (Image credit: ESA)© Provided by Space

What they wanted to see were changes in radio emissions following the X-ray bursts. 

Indeed, the team detected increases in radio brightness within minutes of each single thermonuclear explosion. This led the researchers to conclude that the evolution of jets is closely related to thermonuclear explosions. 

"We were surprised at how clear the response was in the jets. These were very bright and clear flares flowing down the jet that were easily detectable," Russell said. "We did expect some response but thought it would be much more subtle."

Neutron star jets caught speeding

The speeds of these jets was the missing piece of the puzzle, the team says, which led to a link between the jets' violent ejections and explosive feeding events. 

"The speed is incredibly important to understanding how the jets are launched, and this new discovery opens a very accessible window to answer that question," Russell said.  "We can now apply this experiment to many other bursting neutron stars, and we can then compare how the jet speed correlates with the spin, mass, and possibly even magnetic field of the neutron star, all of which are thought to be key ingredients to jet launching." 

Should the team see a correlation between one of those properties and the jet speed, it will reveal what the main launching mechanism for these jets is — be it the spin of the neutron star or the rotation of the infalling material. 

This is the first time the speed of such a jet from a neutron star has been measured, but it's worth noting that it has been measured before for black holes. However, Russell explained that neutron stars have a massive advantage over black holes when it comes to using them as a probe to investigate jet-launching mechanisms.

"Neutron stars can have very precisely measured spins, well-determined masses, and possibly even known magnetic field strengths, all of which are much harder to measure in black holes," he said. "So it is only with neutron stars that we can, currently, begin to connect the system properties with the jets."

All in all, the team has now seen this result in two feeding neutron star systems, but these are the only two they have looked at so far.

"We are applying our new technique to as many other bursting neutron stars as we can to reveal how the jet speeds vary with different neutron star properties," he concluded. "Once we have built a sufficient sample, we will then be able to disentangle the key properties for jet production, revealing how the jets are launched."

The team's research was published on Wednesday (March 27) in the journal Nature. 

Story by Robert Lea; Pace

Lourdes Portillo dead at 80:Oscar-nominated film director has passed away

Mexican Oscar-nominated film director Lourdes Portillo has died at the age of 80

 Lourdes Portillo dead at 80:Oscar-nominated film director has passed away© Oscar-nominated film director Lourdes Portillo has died at the age of 80

Oscar-nominated film director Lourdes Portillo has died at the age of 80. She passed away at her home in San Francisco and according to reports, she was surrounded by her younger sister and three sons when she died. 

The Hollywood Reporter said that “Portillo worked as a writer, director, producer, activist and journalist to create work that centred on Latin American and Mexican stories. Las Madres – The Mothers of the Plaza de Mayo, released in 1985, highlighted the mothers of Argentinian desaparecidos holding weekly protests in Buenos Aires’ Plaza de Mayo during Argentina’s military dictatorship. The documentary was nominated for an Oscar in 1986.”

Loudes Portillo who was born in  Chihuahua, Mexico, on 11 November 1943 and moved to Los Angeles along with her parents and four siblings when she was thirteen years old. 

Lourdes Portillo experienced filmmaking for the first time when she helped a friend out on a documentary. She then received film training and produced her first film ‘After the Earthquake’ or ‘Despues del Terremoto’ in 1979.  

According to Variety, “The Academy Museum of Motion Pictures currently has a gallery experience devoted to Portillo, highlighting her life and career, as a part of its Limited Series and Spotlights. It focuses on key projects of hers including “Las Madres: The Mothers of Plaza de Mayo,” “La Ofrenda: The Days of the Dead,” “The Devil Never Sleeps” and “Señorita Extraviada,” or “Missing Young Woman.”

Lourdes Portillo co-created  ‘Las Madres: The Mothers of Plaza de Mayo’ with filmmaker Susana Blaustein Muñoz,and the movie was nominated for the Academy Award for best documentary feature in 1986. Lourdes has been described as a ‘visual artist, investigative journalist and social activist.’ 

Story by Marina Licht: National World

The moon is 40 million years older — explained

More than 50 years after astronauts returned the last batch of Apollo-era moon rock, scientists said they had made a finding that would have been impossible in 1972.

That was the year astronaut Eugene Cernan and Harrison Schmitt, the first scientist-astronaut became the last humans — so far — to land on the moon. 

Cernan and Schmitt landed in the Taurus-Littrow valley on the edge of Mare Serenitatis, because it was thought to be a geologically diverse site.

They collected a total of 110.5 kilograms (243.6 pounds) of lunar rock and soil — 741 samples in all. The samples include the three major lunar rock types: basalts, breccias, and highland crustal rocks. 

So how old is the moon?

The new study appeared to show that the moon is about 40 million years older than previously thought.

It now seems to have formed about 4.46 billion years (or "GA" — giga annum) ago — putting its formation within the first 110 million years of the birth of our solar system.

Many lunar samples have been studied over the years, but a good amount has been stored and released to researchers only slowly, because scientists predicted early on that technology would improve over time and enable better insights.

The findings published in Geochemical Perspectives Letters on October 23, 2023,

are themselves based on a new technology called atom probe tomography (APT). 

 

Apollo 17 astronauts Harrison and Cernan collected 110.5 kilograms of lunar rock and soil, some of which is still being investigated more than 50 years later© NASA/REUTERS

"I love the fact that this study was done on a sample that was collected and brought to Earth 51 years ago. At that time, atom probe tomography wasn't developed yet and scientists wouldn't have imagined the types of analyses we do today," Philipp Heck, a senior author of the study, told Reuters.   

How did scientists discover the moon's new age?

The scientists re-analyzed crystals from Lunar Sample 72255, which was known to contain 4.2 billion- year-old zircon — some of the oldest ever found.

Zircon is also the oldest mineral known to exist on Earth and, as such, geologists say, it holds vital information about the formation of our planet and life as we know it.

The scientists in the new study used APT, which has nanoscale spatial resolution, to determine the clustering of lead in the samples. The distribution of lead is commonly used to estimate the age of zircon in rock.

Why is zircon relevant to the age of the moon?

In their study, the researchers write that "the leading hypothesis" for the formation of the Earth–Moon system is the Giant Impact hypothesis. A huge object called Theia, which was possibly the size of Mars, is thought to have collided with Earth as it was forming. That, it's said, caused an ejection of debris that quickly formed into the sphere we call our moon. 

That created what is known as the Lunar Magma Ocean — a theory that, the scientists said, explains the composition of the moon's interior.

There were subsequent bombardments of the moon's surface, which the researchers write "reworked and melted the earliest crust," leaving some zircon modified and other zircon pristine, or preserved.

And it was by spotting the preserved zircon within crystal grains from lunar sample 72255 that they were able to redetermine the moon's age, they said.

"I see this as a great example of what the nanoscale, or even atomic scale, can tell us about big-picture questions," Jennika Greer, co-author of the study, told Reuters.

How old is the moon compared to the Earth?

The Earth is estimated to be between 4.5 and 4.6 billion years old. That makes the moon only a fraction younger at 4.46 billion years old. 

Edited by: Derrick Williams: Author: Zulfikar Abbany: Story by Zulfikar Abbany: DW