Of all the numerous and wide-ranging types of stars astronomers and astrophysicists have discovered throughout history, perhaps one of the rarest is a star type known as the Wolf-Rayet, Court House News reported.

First discovered by Charles Wolf and Georges Rayet in the late 1860s, Wolf-Rayet stars are intensely bright and hot stars that, due to their unique makeup, are destined to ultimately collapse on themselves in a supernova explosion that will leave behind nothing but a dark void.

This violent and explosive death for the star type sets it somewhat apart from other forms of star decay, such as white dwarfs that experience a more drawn out and protracted death. The stars are so unique, in fact, that among the cosmos only one in a hundred million stars are classified as a Wolf-Rayet.

While these types of systems are rare enough in their own right, there exists a small and elite group among Wolf-Rayet stars that are even rarer.

These are binary pairs of Wolf-Rayet stars that can produce massive amounts of carbon-based dust that are whipped about by stellar winds, and as the binary Wolf-Rayet stars orbit around one another, the cosmic dust forms a glowing and luminous tail that wraps around the two sister stars.

This intensely rare and beautiful phenomena can only be made possible under the most precise and astronomically unlike conditions, explaining why only a small handful of them have ever been discovered.

Two years ago, this exclusive club welcomed a new member when researchers discovered a star system roughly 8000 light years from Earth that met this qualification, but after further examination, new research shows that it behaves in a way that is unlike any other Wolf-Rayet system experts have ever come across.

In a study published Sunday in the scientific journal Monthly Notices of the Royal Astronomical Society, researchers reveal that they have studied the newly discovered star system, dubbed Apep after the snake-like Egyptian god of chaos, using advanced imaging techniques at the European Southern Observatory’s Very Large Telescope at Paranal in Chile.

Their findings suggest that the Wolf-Rayet is aptly named.

This is due to the fact that like all binary pairs of Wolf-Rayet stars, Apep comes equipped with a swirling spiral of dust that surrounds it, but unlike other Wolf-Rayet systems the dust seems to have a mind of its own.

Rather than swirl with the speed of stellar winds that push it along, the cosmic dust around Apep floats along at a remarkably slower speed than the surrounding winds should dictate — an astrological anomaly.

Researchers made this perplexing discovery by constructing a detailed model that could replicate Apep’s complex spiral structure for the first time, a feat that allowed scientists to study its beautiful but unheard-of behaviors.

Yinuo Han, University of Sydney honors student and lead author of the study who completed the paper while on COVID-19 lockdown, said that the behavior of the newly discovered star left researchers mystified.

“Aside from the stunning image, the most remarkable things about this star system is the way the expansion of its beautiful dust spiral left us totally stumped,” Han said with the release of the study.

While this difference between the speed of the dust spiral and the speed of the surrounding winds is scientifically baffling, it is also extremely noticeable.

Using the newly created model, researchers calculate that the speed of the dust is around four times slower than the speeds of the stellar winds, a significant discrepancy that has never been observed in a star system until now.

A closer look at Apep’s makeup further solidifies the accuracy of its namesake. The two stars that make up the Wolf-Rayet system are around 10 to 15 times larger than the Sun, not to mention more than 100,000 times brighter.

The stellar winds themselves are also highly extreme in nature, with experts saying they are coming off Apep at around 12 million kilometers an hour, roughly 1% the speed of light.

Researchers suggest that it is perhaps the wind speed and the speed at which the stars rotate that could potentially explain the confusing dust movement.

“It likely means that stellar winds are launched in different directions at different speeds,” Han said. “The dust expansion we are measuring is driven by slower winds launched near the star’s equator.”

Researchers are also speculating on what the future of Apep may hold — a future that is likely to be quite destructive.

Data shows that on top of carrying all of the typically extreme characteristics of a Wolf-Rayet, Apep’s main star seems to rotate at remarkable speed, potentially giving it the ability to detonate a long gamma-ray explosion when the system ultimately goes supernova.

This potential future could prove disastrous for nearby systems, given that gamma-ray bursts are some of the most energetic natural events in the known universe.

These bursts are so potentially deadly that if such a burst were to ever strike Earth, the force from the blast could destroy the ozone layer around our planet that acts as a protective shield from the radiation of the Sun.

Researchers say, however, that there is no reason for anyone to fear Apep’s explosive potential. Due to the star system’s axis of rotation, any future blasts would not come within striking distance of Earth.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), the team revealed that the molecular clouds in the galaxy are highly unstable, which leads to runaway star formation. Monster galaxies are thought to be the ancestors of the huge elliptical galaxies in today’s universe, therefore these findings pave the way to understand the formation and evolution of such galaxies.

“One of the best parts of ALMA observations is to see the far-away galaxies with unprecedented resolution,” says Ken-ichi Tadaki, a postdoctoral researcher at the Japan Society for the Promotion of Science and the National Astronomical Observatory of Japan, the lead author of the research paper published in the journal Nature.

The monster galaxy COSMOS-AzTEC-1 is located 12.4 billion light-years away and is forming stars 1000 times more rapidly than our Milky Way Galaxy. ALMA observations revealed dense gas concentrations in the disk, and intense star formation in those concentrations.

Monster galaxies, or starburst galaxies, form stars at a startling pace; 1000 times higher than the star formation in our Galaxy. But why are they so active? To tackle this problem, researchers need to know the environment around the stellar nurseries. Drawing detailed maps of molecular clouds is an important step to scout a cosmic monster.

Tadaki and the team targeted a chimerical galaxy COSMOS-AzTEC-1. This galaxy was first discovered with the James Clerk Maxwell Telescope in Hawaii, and later the Large Millimeter Telescope (LMT) in Mexico found an enormous amount of carbon monoxide gas in the galaxy and revealed its hidden starburst. The LMT observations also measured the distance to the galaxy, and found that it is 12.4 billion light-years.

Researchers have found that COSMOS-AzTEC-1 is rich with the ingredients of stars, but it was still difficult to figure out the nature of the cosmic gas in the galaxy. The team utilized the high resolution and high sensitivity of ALMA to observe this monster galaxy and obtain a detailed map of the distribution and the motion of the gas. Thanks to the most extended ALMA antenna configuration of 16 km, this is the highest resolution molecular gas map of a distant monster galaxy ever made.

“We found that there are two distinct large clouds several thousand light-years away from the center,” explains Tadaki. “In most distant starburst galaxies, stars are actively formed in the center. So it is surprising to find off-center clouds.”

The astronomers further investigated the nature of the gas in COSMOS-AzTEC-1 and found that the clouds throughout the galaxy are very unstable, which is unusual. In a normal situation, the inward gravity and outward pressure are balanced in the clouds. Once gravity overcomes pressure, the gas cloud collapses and forms stars at a rapid pace. Then, stars and supernova explosions at the end of the stellar life cycle blast out gases, which increase the outward pressure.

As a result, the gravity and pressure reach a balanced state and star formation continues at a moderate pace. In this way star formation in galaxies is self-regulating. But, in COSMOS-AzTEC-1, the pressure is far weaker than the gravity and hard to balance. Therefore this galaxy shows runaway star formation and has morphed into an unstoppable monster galaxy.

The team estimated that the gas in COSMOS-AzTEC-1 will be completely consumed in 100 million years, which is 10 times faster than in other star forming galaxies.

But why is the gas in COSMOS-AzTEC-1 so unstable? Researchers do not have a definitive answer yet, but galaxy merger is a possible cause. Galaxy collision may have efficiently transported the gas into a small area and ignited intense star formation.

“At this moment, we have no evidence of merger in this galaxy. By observing other similar galaxies with ALMA, we want to unveil the relation between galaxy mergers and monster galaxies,” summarizes Tadaki.

But there’s also some unsettling news: The new number remains at odds with independent measurements of the early universe’s expansion, which could mean that there is something unknown about the makeup of the universe.

Is something unpredicted going on in the depths of space?

“The community is really grappling with understanding the meaning of this discrepancy,” says Adam Riess, who leads a team of researchers using the Hubble Space Telescope seeking to measure the expansion rate of the universe.

There’s a gap

The team, which includes researchers from Johns Hopkins University and the Space Telescope Science Institute, has used the Hubble telescope over the past six years to refine the measurements of the distances to galaxies. Those measurements are used to calculate how fast the universe expands with time, a value known as the Hubble constant.

Separate measurements from the European Space Agency’s Planck satellite, which maps the cosmic microwave background, predicted that the Hubble constant value should now be 67 kilometers per second per megaparsec. This would mean that for every 3.3 million light-years farther a galaxy is away from us, it is moving 67 kilometers per second faster.

But Riess’s team measured a value of 73 kilometers per second per megaparsec, indicating galaxies are moving at a faster rate than implied by the Planck satellite observations of the early universe.

The Hubble data are so precise that astronomers cannot dismiss the gap between the two results as errors in any single measurement or method.

“Both results have been tested multiple ways,” explains Riess, a professor at Johns Hopkins and co-winner of the Nobel Prize in 2011 for the discovery of the accelerating universe. “Barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe.”

3 possible scenarios

Riess outlines a few possible explanations for the mismatch, all related to the 95 percent of the universe shrouded in darkness. One possibility is that dark energy, already known to be accelerating the cosmos, may be shoving galaxies away from each other with even greater—or growing—strength. This means that the acceleration itself might not have a constant value in the universe but changes over time.

Another idea is that the universe contains a previously unknown new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called “dark radiation” and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays. Unlike a normal neutrino, which interacts by a subatomic force, this possible new particle would be affected only by gravity and is dubbed a “sterile neutrino.”

Yet another attractive possibility is that dark matter—an invisible form of matter not made up of protons, neutrons, and electrons—interacts more strongly with normal matter or radiation than previously assumed.

Any of those three scenarios being true would make for inconsistencies in theoretical models, resulting in an incorrect value for the Hubble constant, as measured by the Planck satellite. This value would then be at odds with the number Riess and his team derived from the Hubble observations.

Riess and his colleagues will continue to work on fine-tuning their measurement of the universe’s expansion rate. So far the team, called the Supernova H0 for the Equation of State—nicknamed SH0ES—has decreased the uncertainty to 2.3 percent.

The team’s latest results will appear in the Astrophysical Journal. NASA, the National Science Foundation, and other funders support the work.

For close to a century, researchers have hypothesized that the universe contains more matter than can be directly observed, known as “dark matter”.

They have also posited the existence of a “dark energy” that is more powerful than gravitational attraction.

These two hypotheses, it has been argued, account for the movement of stars in galaxies and for the accelerating expansion of the universe respectively.

However, according to a researcher at the University of Geneva (UNIGE) in Switzerland, these concepts may be no longer valid: the phenomena they are supposed to describe can be demonstrated without them.

The research, published in The Astrophysical Journal, exploits a new theoretical model based on the scale invariance of the empty space, potentially solving two of astronomy’s greatest mysteries.

The way we represent the universe and its history are described by Einstein’s equations of general relativity, Newton’s universal gravitation and quantum mechanics.

The model-consensus at present is that of a Big Bang followed by an expansion.

“In this model, there is a starting hypothesis that has not been taken into account, in my opinion,” said Andre Maeder, professor in UNIGE’s Faculty of Science.

“By that I mean the scale invariance of the empty space; in other words, the empty space and its properties do not change following a dilatation or contraction,” said Maeder.

The empty space plays a primordial role in Einstein’s equations as it operates in a quantity known as a “cosmological constant”, and the resulting universe model depends on it.

Based on this hypothesis, Maeder is now re-examining the model of the universe, pointing out that the scale invariance of the empty space is also present in the fundamental theory of electromagnetism.

When Maeder carried out cosmological tests on his new model, he found that it matched the observations.

He also found that the model predicts the accelerated expansion of the universe without having to factor in any particle or dark energy.

In short, it appears that dark energy may not actually exist since the acceleration of the expansion is contained in the equations of the physics, researchers said.

In a second stage, Maeder focused on Newton’s law, a specific instance of the equations of general relativity.

The law is also slightly modified when the model incorporates Maeder’s new hypothesis.

It contains a very small outward acceleration term, which is particularly significant at low densities.

This amended law, when applied to clusters of galaxies, leads to masses of clusters in line with that of visible matter: this means that no dark matter is needed to explain the high speeds of the galaxies in the clusters.