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Space Exploration

Even Stars Can Get the Hiccups: Exploring Cosmic Anomalies and Their Causes

By Jonathan Bala December 31, 2024

Even Stars Can Get the Hiccups: Exploring Cosmic Anomalies and Their Causes

The concept of “stellar hiccups” reveals a fascinating phase in the lives of massive stars, where rapid core expansions and contractions can precede supernova explosions. This newly observed phenomenon, known as “pulsational pair-instability,” enhances our understanding of stellar evolution and the cosmic processes that shape the universe.

Summary

Stellar hiccups are rare, observable pre-supernova phases in stars with masses ranging between 60-150 times that of the Sun.
The phenomenon is caused by pulsational pair-instability (PPI), where the stellar core rapidly contracts and expands under extreme temperatures.
Massive stars nearing the end of their lifespans eject shells of material during these “hiccup” events, creating bursts of energy visible from Earth.
These “hiccups” help scientists understand how massive stars shed mass and transition to the supernova stage.
The discovery of SN2020acct in the NGC2981 galaxy provided the first-ever observation of this phenomenon.
The core mechanism involves material ejection due to unstable thermonuclear reactions in massive stars, followed by collisions between ejected shells of gas.
This process was theorized for decades but remained unobserved due to its rarity and faintness.
Observing hiccups can aid in predicting supernova occurrences and understanding element distribution in the universe.
The remnants of these massive explosions create neutron stars or black holes, depending on the progenitor’s mass.
The study also sheds light on the role of supernovae in spreading heavy elements critical for forming planets and life.

Even Stars Can Get the Hiccups Exploring Cosmic Anomalies and Their Causes — This new picture comes from the VLT Survey Telescope (VST) at ESO’s Paranal Observatory. It shows the impressive super star cluster called Westerlund 1. This bright cluster is about 16,000 light-years from Earth. It is located in the southern constellation of Ara, also known as The Altar. The cluster contains hundreds of very large and bright stars. These stars are only a few million years old, which is very young for stars.
However, we can’t see this cluster clearly because gas and dust block most of its visible light from reaching Earth. Recently, astronomers found something unexpected while studying images of Westerlund 1. These images are from a new survey of the southern skies. They discovered clouds of glowing hydrogen gas around one of the stars in the cluster. This star is called W26. W26 is a red supergiant and might be the biggest star known.
Glowing clouds around massive stars are very rare. They are even rarer around a red supergiant. In fact, this is the first ionised nebula found around such a star. An ionised nebula is a glowing cloud of gas that usually surrounds stars. W26 is too cool to make the gas glow by itself. The astronomers think that the gas glows due to radiation from somewhere else. The source might be hot blue stars elsewhere in the cluster or a much hotter companion star to W26.
W26 will eventually explode as a supernova. A supernova is a powerful explosion that happens when a star dies. The nebula around W26 is similar to the one that surrounded SN1987A. SN1987A is the remains of a star that became a supernova in 1987. It was the closest supernova to Earth observed since 1604. This gave astronomers a chance to learn more about these explosions.
By studying objects like the new nebula around W26, astronomers can understand how massive stars lose mass before exploding. Understanding these processes helps scientists learn more about the life and death of stars.
This picture is part of a detailed survey of a large part of the Milky Way. The survey is called VPHAS+ and uses the VST’s power to find new objects like young stars and planetary nebulae. A planetary nebula is a glowing shell of gas and dust around an old star. A recent picture of the Prawn Nebula also came from this survey.

Cosmic Context of Stellar Hiccups

Stars are colossal nuclear furnaces, responsible for producing and dispersing heavy elements essential for the formation of planets and life. Among these stars, massive ones often live dramatically short lives, culminating in supernova explosions that distribute their materials into space. However, before the grand finale of a supernova, some stars exhibit unique “hiccups” due to a rare process called pulsational pair-instability (PPI).

What Are Stellar Hiccups?

PPI causes the cores of massive stars to rapidly expand and contract, ejecting shells of material in the process. These hiccups are short-lived, occurring just years, or even days, before a supernova.

In December 2020, astronomers discovered one such hiccup in the galaxy NGC2981, marking the first observation of this fascinating event.

The Science Behind Pulsational Pair-Instability

The term pulsational pair-instability refers to a rare phenomenon where conditions in a star’s core destabilize due to:

Extreme Heat: Stars exceeding 60 times the Sun’s mass reach temperatures high enough to produce electron-positron pairs, reducing radiation pressure.
Core Collapse: Reduced pressure causes the core to collapse under gravity.
Rapid Expansion: Nuclear reactions reignite, causing the core to expand and eject material in violent bursts.

How PPI Affects Stellar Evolution

Each hiccup expels part of the star’s mass, lowering its overall size and altering its eventual fate. Over time, the remaining core becomes unstable enough to collapse into either a neutron star or a black hole.

Observed Phenomenon: The Case of SN2020acct

The Fred Lawrence Whipple Observatory detected SN2020acct, initially classified as a supernova. However, astronomers later discovered that the light emitted was not a supernova but the result of material shells colliding near the star.

Observation Timeline	Key Events
December 2020	SN2020acct discovered in NGC2981
February 2021	Unusual light reappeared in the same region
Detailed Analysis	Confirmed “hiccups” as the cause

Why Are Stellar Hiccups Important?

Stellar hiccups provide insights into the processes that precede supernovae, which are critical for understanding:

Elemental Formation: The heavy elements necessary for life are created during these events.
Massive Star Evolution: PPI events help explain how massive stars lose mass before exploding.
Supernova Prediction: Observing hiccups can refine supernova timelines, aiding astronomical studies.

Supernovae: The Aftermath of Stellar Hiccups

Supernovae are categorized into two primary types:

Supernova Type	Key Features
Type I	Occurs in binary star systems; involves the accumulation of matter on a white dwarf.
Type II	Marks the death of a massive star; involves core collapse and violent expulsion of outer layers.

Facts About Stellar Hiccups

Stellar hiccups are believed to occur in stars 60-150 times the mass of the Sun.
The phenomenon was only theorized until its first observation in 2020.
Hiccups can lead to repetitive light bursts from stars before they die.
The Pinwheel Galaxy (Messier 101) recently hosted one of the brightest supernova events related to stellar hiccups.

Applications and Future Research

Astronomers aim to leverage telescopic advancements to:

Detect more stars exhibiting hiccups.
Study their frequency and duration.
Develop models predicting supernova timings.

Stellar hiccups provide a rare glimpse into the chaotic lives of massive stars nearing their end. Observing these events enhances our understanding of supernovae, the creation of heavy elements, and the intricate processes that govern our universe.

The discovery of SN2020acct marked a pivotal moment in astronomy, highlighting the importance of continued research into cosmic anomalies. As technology advances, astronomers hope to unlock more secrets of the universe, expanding humanity’s understanding of the cosmos.

References

#cosmicphenomena, #stellarhiccups, #astronomyresearch, #supernovaexploration, #universesecrets, #astronomydiscoveries, #NASA, #ESO, #cosmicevents, #galaxies, #astronomicalscience, #stars, #universe, #spaceexploration, #astrophysics

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Space Exploration

Scientists Believe Something Big May Have Altered the Solar System’s Planetary Order

By Jonathan Bala December 13, 2024

Scientists Believe Something Big May Have Altered the Solar System’s Planetary Order

Scientists propose that a massive interstellar object, possibly fifty times the mass of Jupiter, may have passed through our solar system billions of years ago. This cosmic intruder could have dramatically disrupted planetary orbits, reshaping the solar system’s structure.

Summary

The solar system is organized due to the Sun’s gravitational pull, with planets moving in the same direction and on the same plane.
Certain orbital anomalies in the solar system suggest an event disrupted this balance.
A recent study hypothesizes an interstellar object, 2-50 times the mass of Jupiter, may have flown within 20 astronomical units of the Sun, altering planetary positions.
This theory supports planetary migrations, where planets like Uranus and Neptune moved from their original orbits closer to the Sun.
Previously, planetary migrations were attributed to gravitational interactions between planets and the protoplanetary disk.
Gas giants like Jupiter, Saturn, Uranus, and Neptune exhibit eccentric orbits that existing theories struggle to fully explain.
Researchers used computer simulations to model how such a massive intruder could influence planetary arrangements.
The probability of such an interstellar flyby happening is approximately 1 in 100.
The mystery object could have been a rogue gas giant ejected from another star system.
If true, this event would underscore the vulnerability of even stable star systems to external cosmic influences.
Observational evidence and future studies may help verify this theory.
Similar anomalies have been observed in other star systems, hinting at a common cosmic phenomenon.
Gravitational forces from interstellar objects can not only disrupt orbits but also eject planets entirely from their systems.
This study provides an alternative explanation for the current arrangement of our solar system’s gas giants.
Interstellar visitors could be more common than previously thought, emphasizing the dynamic and chaotic nature of space.

Scientists Believe Something Big May Have Altered the Solar System's Planetary Order — 3D Rendering. Futuristic interior environment

Disorder of the Day

The Sun, often referred to as a benevolent dictator, has maintained the solar system’s order for billions of years. Its gravitational pull ensures the planets revolve on the same plane and in the same direction. Yet, subtle anomalies in this cosmic choreography suggest that something significant may have disrupted this balance billions of years ago.

Recent studies suggest an enormous interstellar object, potentially up to fifty times the mass of Jupiter, may have invaded our solar system. This visitor could have stirred up planetary orbits, leaving behind the irregularities we observe today.

“The solar system may be a product not just of internal forces but also of a dramatic encounter with an external invader,” says a researcher involved in the study.

This hypothesis aligns with other theories proposing that interstellar flybys have influenced orbital patterns in various star systems.

The Protoplanetary Disk and Planetary Formation

Around 4.6 billion years ago, the solar system emerged from a rotating cloud of gas and dust known as the protoplanetary disk. This disk’s influence explains why planets are generally coplanar and move in the same direction. However, as the planets formed, their positions shifted.

Astronomers refer to this as planetary migrations, which account for how planets like Uranus and Neptune moved farther from the Sun. Smaller planetary bodies were often ejected from the system entirely.

Space Invader Hypothesis

The study suggests that an interstellar object, between 2-50 times the mass of Jupiter, might have flown within 20 astronomical units of the Sun. This close encounter could have disturbed the orbits of the gas giants, leading to the eccentricities observed today.

The computer simulations conducted indicate a 1 in 100 chance of such an event occurring. While seemingly low, these are relatively high odds in the realm of astronomy.

Table 1: Key Characteristics of Planetary Migrations

Phenomenon	Description
Gravitational Interactions	Planets push and pull each other, causing orbital shifts.
Protoplanetary Disk	The disk of gas and dust around the Sun influences the movement of forming planets.
Interstellar Flyby	A massive object from another star system disturbs planetary orbits.

What Was This Cosmic Intruder?

The mysterious object could have been a rogue gas giant, ejected from another star system. Such objects are common in the galaxy, traveling vast distances through interstellar space. If this theory holds, it would mean our solar system was directly impacted by one of these wanderers.

Implications of the Hypothesis

If validated, the interstellar object theory would rewrite our understanding of planetary formation and stability. It suggests that even star systems as stable as ours are vulnerable to external disruptions.

Astronomers also believe that similar events might occur in other star systems, emphasizing the chaotic nature of the universe.

Table 2: Possible Outcomes of Interstellar Flybys

Outcome	Explanation
Orbital Eccentricities	Planets adopt irregular, elongated orbits.
Planetary Ejections	Smaller planets or debris may be flung out of the solar system entirely.
Altered Planetary Layout	Gas giants and terrestrial planets shift from their original positions.

Fun Facts

A rogue planet traveling through space can take millions of years to reach another star system.
Interstellar flybys may also leave behind traces in the form of cometary debris.
Planetary migrations were first proposed to explain Neptune’s unexpected position.

References

#SolarSystem, #Interstellar, #PlanetaryMigrations, #Astronomy, #SpaceScience, #CosmicEvents, #GasGiants, #PlanetaryFormation, #OrbitalAnomalies, #AstronomicalResearch, #SpaceExploration, #RoguePlanets, #ScienceBreakthroughs, #CosmicMysteries, #SpacePhysics

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Space Exploration

Neutron Star Collisions and the Early Universe: A Remarkable Cosmic Parallel

By Jonathan Bala November 2, 2024

Neutron Star Collisions and the Early Universe: A Remarkable Cosmic Parallel

The phenomenon of neutron star collisions, resulting in powerful explosions known as kilonovae, holds crucial clues about the early universe. These collisions produce a plasma state reminiscent of the early Big Bang era, create heavy elements through nucleosynthesis, and have led to groundbreaking insights into the nature of atomic formation. The kilonova event AT2017gfo provided an unprecedented glimpse into the universe’s material evolution and the formation of a black hole, shedding light on cosmic processes that took place billions of years ago.

Summary

Neutron stars are highly dense stellar remnants, packing massive amounts of matter into small volumes.
When two neutron stars collide, the resulting kilonova explosion releases vast energy, creating conditions similar to those of the early universe.
The kilonova AT2017gfo, observed in 2017, was the first confirmed observation of its kind, providing critical data on heavy element formation.
This explosion created elements through the rapid neutron capture process (r-process), leading to the formation of gold, platinum, and uranium.
By analyzing spectra from telescopes around the globe and Hubble in orbit, researchers watched as atoms formed in real-time, for the first time.
The event also suggests the creation of a black hole, showcasing the formation of extreme celestial objects in neutron star mergers.
Researchers believe kilonovae contribute significantly to the universe’s heavy elements, pushing forward our understanding of nucleosynthesis.

Main Article

Neutron stars represent some of the densest objects in the universe, remnants of massive stars that have undergone supernova explosions. They’re typically about 20 kilometers in diameter but pack the mass of several suns, resulting in extreme gravitational fields. When two neutron stars collide, they produce a phenomenon known as a kilonova — an explosion that is among the most energetic events in the cosmos. This event releases elements and radiation that help us better understand the universe’s origins and development, much like the Big Bang itself.

A Glimpse of the Early Universe

The process following a neutron star collision and the subsequent kilonova explosion shares remarkable parallels with conditions just after the Big Bang. At that time, the universe was a hot, dense plasma where atomic nuclei and electrons were separated. In a similar fashion, neutron star collisions release enough energy to create a plasma of detached electrons and atomic nuclei. However, as the plasma cools, these particles can combine to form atoms through a process called nucleosynthesis.

“For the first time, we see the creation of atoms in a cosmic event,” remarked Rasmus Damgaard, Ph.D. student at the Cosmic DAWN Center. This discovery demonstrates the process of atomic formation and material cooling that characterizes both kilonovae and the early universe.

Understanding Nucleosynthesis

Nucleosynthesis — the formation of atomic nuclei from protons and neutrons — occurs in various astrophysical environments. There are three main processes:

Slow neutron capture (s-process)
Proton process (p-process)
Rapid neutron capture (r-process)

In kilonovae, rapid neutron capture (r-process) is dominant, which is responsible for producing many of the universe’s heaviest elements, including gold, platinum, and uranium.

Below is a table showing these three nucleosynthesis processes and their primary characteristics.

Process	Environment	Key Elements Produced
s-process	Stellar environments	Copper, silver, lead
p-process	Supernova environments	Selenium, molybdenum, tellurium
r-process	Kilonova environments	Gold, platinum, uranium

The Historic Observation of AT2017gfo

The kilonova event AT2017gfo marked a breakthrough in astrophysics, as it allowed scientists to witness nucleosynthesis in real time. Discovered in 2017, this kilonova was observed in conjunction with gravitational waves from the event GW170817, detected by LIGO. It was a defining moment because the gravitational wave detection provided additional information about the physical conditions during the collision, leading to the most detailed analysis of a kilonova to date.

Neutron Star Collisions and the Early Universe A Remarkable Cosmic Parallel — An artist created this illustration. It shows a collision between two neutron stars. This collision leaves a fast-growing cloud of radioactive material. The conditions in this cloud are similar to those in the early Universe. This was shortly after the Big Bang occurred. The image is credited to NASA GODDARD SPACE FLIGHT CENTER, CI LAB.
A neutron star is an extremely dense star that forms after a supernova explosion. A supernova is a powerful explosion that happens when a star dies. The Big Bang is a scientific theory explaining how the Universe began. It started with a small, hot, and dense point that expanded rapidly.

Challenges in Observation

Kilonovae, despite their energy output, are transient and fade within days, making them challenging to observe. The Earth’s rotation limits telescope views to certain times, so researchers had to piece together data from multiple sources worldwide, including telescopes in Australia, South Africa, and the Hubble Space Telescope in low-Earth orbit. “The viewing angle of individual telescopes is blocked by Earth’s rotation,” noted Albert Sneppen from the Cosmic Dawn Center. Combining observations from different sites provided a fuller view of the kilonova’s evolution.

Revealing Atomic Synthesis through Spectroscopy

By analyzing the spectra collected from AT2017gfo between 0.5 and 9.4 days after the event, researchers focused on optical and near-infrared (NIR) wavelengths, as shorter wavelengths like X-rays and ultraviolet (UV) were opaque at that stage. These spectra revealed the formation of elements like strontium, tellurium, lanthanum, cesium, and yttrium. These findings were derived by studying a P Cygni spectral line — an indicator of an expanding shell of gas around the kilonova — which provided data on velocity, density, and other parameters of the ejecta.

Observation Wavelength	Importance	Notable Elements Observed
Optical	High visibility in early cooling stages	Strontium
Near-infrared (NIR)	Penetrates thick ejecta to reveal more details	Lanthanum, Tellurium

Cosmic Implications: Heavy Elements and Black Holes

Neutron star collisions do more than create heavy elements; they also often result in black hole formation. Following the AT2017gfo explosion, researchers identified evidence suggesting the creation of one of the smallest black holes observed. The event’s gravitational wave signature, GW170817, was detected by LIGO and provided data that supported the formation of a black hole, though there is still speculation about the possibility of a magnetar — a type of neutron star with an ultra-strong magnetic field — being involved.

“The matter expands so fast and gains in size so rapidly that it takes hours for the light to travel across the explosion. Observing the farthest end of the fireball takes us further back in the history of the explosion,” said Kasper Heintz, assistant professor at the Niels Bohr Institute.

Kilonovae as Cosmic Laboratories

Kilonovae serve as natural laboratories where extreme physics plays out on a cosmic scale. Their environments allow scientists to study nuclear reactions that are impossible to replicate on Earth. The heavy elements produced, especially gold and platinum, highlight the importance of kilonovae in enriching the galaxy with these rare elements.

Facts About Neutron Star Collisions and Kilonovae

Small but Mighty: A neutron star is about the size of a city, yet it can weigh as much as 2.5 times the sun.
Blinding Brightness: Kilonovae can outshine entire galaxies for a brief period.
Gold in Space: Neutron star collisions are responsible for creating around 10 Earth masses of gold in a single explosion.

The Role of Advanced Telescopes in Kilonova Research

The study of neutron star collisions has advanced significantly due to telescopes like Hubble and LIGO. The ability to detect gravitational waves has enabled astronomers to pinpoint collision events with accuracy. The multi-telescope approach, as seen in the study of AT2017gfo, allowed scientists to observe these high-energy events from multiple angles.

The study of neutron star collisions and kilonovae provides profound insights into the early universe and the formation of elements essential to life on Earth. The event AT2017gfo stands as a testament to the strides made in astrophysics, unveiling the mysteries of atomic synthesis and black hole formation. As technology advances, we are likely to witness even more detailed observations of these celestial events, furthering our understanding of the cosmos.

#NeutronStarCollision, #Kilonova, #EarlyUniverse, #AT2017gfo, #BlackHole, #Astrophysics, #Nucleosynthesis, #HubbleTelescope, #LIGO, #GravitationalWaves, #CosmicEvents, #HeavyElements, #RProcess, #Astronomy, #SpacePhysics

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