• We have updated the guidelines regarding posting political content: please see the stickied thread on Website Issues.

Astronomical News

This unreal image of the Milky Way's center could rewrite galactic history

Source: cnet.com
Date: 16 December, 2019

A survey of 700,000 stars at the Milky Way's center suggests a violent outburst of star-forming activity 1 billion years ago.

A breakthrough survey of over 700,000 stars near the Milky Way's galactic center has produced one of the most stunning images of our home galaxy. Astronomers studying the massive population of stars in the "nuclear disk" at the center of the galaxy hypothesize there were two major periods of star formation in the region, contradicting earlier beliefs it was in a near-constant state of star formation.

The study, published in the journal Nature Astronomy on Dec. 16, gathered the new images using the High Acuity Wide-field K-band Imager (HAWK-I) on the Very Large Telescope (VLT) in Chile, which is able to image the cosmos in near-infrared bands. That allows the astronomers to peer through much of the dense gas and debris that clouds our vision of the Milky Way's center...

[...]

The new research shows the Milky Way's early life was particularly fruitful for the nuclear disk. During the galaxy's first 5 billion years, over 80% of the galaxy's stars were born, but then it dipped into a "quiescent" state, where star formation dropped away. But a huge increase in activity occurred just 1 billion years ago, when approximately 5% of the center's stellar mass suddenly burst to life.

https://www-cnet-com.cdn.ampproject...-milky-ways-center-rewrites-galactic-history/
 
Cosmology in crisis as evidence suggests our universe isn’t flat, it’s actually curved

Source: thenextweb.com
Date: 17 December, 2019

No matter how elegant your theory is, experimental data will have the last word. Observations of the retrograde motion of the planets were fundamental to the Copernican revolution, in which the sun replaced Earth at the centre of the solar system. And the unusual orbit of Mercury provided a spectacular confirmation of the theory of general relativity. In fact, our entire understanding of the universe is built on observed, unexpected anomalies.

Now our new paper, published in Nature Astronomy, has come to a conclusion that may unleash a crisis in cosmology – if confirmed. We show that the shape of the universe may actually be curved rather than flat, as previously thought – with a probability larger than 99 percent. In a curved universe, no matter which direction you travel in, you will end up at the starting point – just like on a sphere. Though the universe has four dimensions, including time.

https://thenextweb.com/syndication/...s-our-universe-isnt-flat-its-actually-curved/
 
Astrophysicists Developed a New Theory to Explain ‘Dark Energy’

Source: Immanuel Kant Baltic Federal University/scitechdaily.com
Date: 24 December, 2019

The fact that our Universe is expanding was discovered almost a hundred years ago, but how exactly this happens, scientists realized only in the 90s of the last century, when powerful telescopes (including orbital ones) appeared and the era of exact cosmo.

International Journal of Modern Physics has published an article by the IKBFU Physics and Mathematics Institute Artyom Astashenok and the Institute’s MA student Alexander Teplyakov. The article refers to the issue of the “Dark Enegry” and an assumption is made that the Universe has borders.

Artyom Astashenok told:

“The fact that our Universe is expanding was discovered almost a hundred years ago, but how exactly this happens, scientists realized only in the 90s of the last century, when powerful telescopes (including orbital ones) appeared and the era of exact cosmology began. In the course of observations and analysis of the data obtained, it turned out that the Universe is not just expanding, but expanding with acceleration, which began three to four billion years after the birth of the Universe.”

For a long time, it was believed that space is filled with ordinary matter — stars, planets, asteroids, comets and highly rarefied intergalactic gas. But, if this is so, then accelerated expansion is contrary to the law of gravity, which says that bodies are attracted to each other. Gravitational forces tend to slow down the expansion of the universe, but cannot accelerate it.

Artyom Astashenok says:

“And then the idea was born that the Universe is filled for the most part not with ordinary matter, but with some “dark energy,” which has special properties. No one knows what is it and how it works, so it named “Dark Energy” as something unknown. And 70% of the Universe consists of this Energy.”

There are many theories of what the “Dark Energy” is, and the IKBFU scientists presented their own theory.

“The so-called Casimir effect (named after the Dutch physicist Hendrik Casimir), which consists in the fact that two metal plates placed in a vacuum are attracted to each other, has long been known. It would seem that this cannot be, because there is nothing in the vacuum. But in fact, according to quantum theory, particles constantly appear and disappear there, and as a result of their interaction with plates, which indicate certain boundaries of space (which is extremely important), a very small attraction occurs. And there is an idea according to this, approximately the same thing happens in space. Only this leads, on the contrary, to additional repulsion, which accelerates the expansion of the Universe. That is, there is essentially no “Dark Energy,” but there is a manifestation of the boundaries of the Universe. This, of course, does not mean that it ends somewhere, but some kind of complex topology can take place. You can draw an analogy with the Earth. After all, it also has no boundaries, but it is finite. The difference between the Earth and the Universe is that in the first case we are dealing with two-dimensional space, and in the second — with three-dimensional.”

https://scitechdaily-com.cdn.amppro...eveloped-a-new-theory-to-explain-dark-energy/
 
GBywUyvCYYoNHrsCoZj7Le-970-80.jpg

'Ring of Fire' Solar Eclipse Thrills Skywatchers Around the World (and in Space, Too!)

By Tariq Malik 2 days ago
It was the last solar eclipse of the decade.
https://www.space.com/ring-of-fire-...ZtBpVcbUx3CCbBZNunC8uXM_jnTNkSp4wHfwiUoGhA1Tt


 
Just don't say 'Betelgeuse' 3 times in a row and we'll be OK.

As a slight aside, I'd grown up thinking it was pronounced 'bettelgewz' and was quite surprised when I found out, years ago, that it was pronounced 'beetlejuice'. But I flatly refuse to pronounce it as that because it just sounds silly to me. So I carry on with the pronunciation I prefer :)
 
May be of interest.

The variation in Betelgeuse's brightness was described in 1836 by Sir John Herschel, when he published his observations in Outlines of Astronomy. From 1836 to 1840, he noticed significant changes in magnitude when Betelgeuse outshone Rigel in October 1837 and again in November 1839.[25] A 10-year quiescent period followed; then in 1849, Herschel noted another short cycle of variability, which peaked in 1852. Later observers recorded unusually high maxima with an interval of years, but only small variations from 1957 to 1967. The records of the American Association of Variable Star Observers (AAVSO) show a maximum brightness of 0.2 in 1933 and 1942, and a minimum of 1.2, observed in 1927 and 1941.[26][27] This variability in brightness may explain why Johann Bayer, with the publication of his Uranometria in 1603, designated the star alpha as it probably rivaled the usually brighter Rigel (beta).[28] From Arctic latitudes, Betelgeuse's red colour and higher location in the sky than Rigel meant the Inuit regarded it as brighter, and one local name was Ulluriajjuaq "large star".[29]

Wikipedia
 
Darkest Galaxies in the Universe Provide New Clues on Dark Matter

Source: SciTechDaily
Date: 2 January, 2020

A study by Scuola Internazionale Superiore di Studi Avanzati (SISSA) provides important information on its composition and on its interaction with luminous matter.

They are called low-surface-brightness galaxies and it is thanks to them that important confirmations and new information have been obtained on one of the largest mysteries of the cosmos: dark matter. “We have found that disc galaxies can be represented by a universal relationship. In particular, in this study we analyzed the so-called Low-Surface-Brightness (LSB) galaxies, a particular type of galaxy with a rotating disc called this way because they have a low-density brightness “says Chiara di Paolo, astrophysicist at SISSA and lead author of a study recently published in MNRAS together with Paolo Salucci (astrophysicist at SISSA) and Erkurt Adnan (Istanbul University).

The researchers analyzed the speed at which the stars and gases that compose the galaxies subject matter of the study rotate, noting that the LSBs also have a very homogenous behavior. This result consolidates several clues on the presence and behavior of dark matter, opening up new scenarios on its interactions with bright matter.

https://scitechdaily-com.cdn.amppro...he-universe-provide-new-clues-on-dark-matter/
 
We May Finally Understand the Moments Before the Big Bang

Physicists may have solved a decades-long mystery about how our universe came to be.

Source: livescience.com
Date : 11 November, 2019

There's a hole in the story of how our universe came to be. First, the universe inflated rapidly, like a balloon. Then, everything went boom.

But how those two periods are connected has eluded physicists. Now, a new study suggests a way to link the two epochs.

In the first period, the universe grew from an almost infinitely small point to nearly an octillion (that's a 1 followed by 27 zeros) times that in size in less than a trillionth of a second. This inflation period was followed by a more gradual, but violent, period of expansion we know as the Big Bang. During the Big Bang, an incredibly hot fireball of fundamental particles — such as protons, neutrons and electrons — expanded and cooled to form the atoms, stars and galaxies we see today.

The Big Bang theory, which describes cosmic inflation, remains the most widely supported explanation of how our universe began, yet scientists are still perplexed by how these wholly different periods of expansion are connected. To solve this cosmic conundrum, a team of researchers at Kenyon College, the Massachusetts Institute of Technology (MIT) and the Netherlands' Leiden University simulated the critical transition between cosmic inflation and the Big Bang — a period they call "reheating."

https://www.livescience.com/physicists-model-reheating-universe.html
 
We May Finally Understand the Moments Before the Big Bang

The article states:

"During the Big Bang, an incredibly hot fireball of fundamental particles — such as protons, neutrons and electrons — expanded and cooled to form the atoms, stars and galaxies we see today".

Where did those fundamental particles come from?

Just wondered... :btime:
 
We May Finally Understand the Moments Before the Big Bang

The article states:

"During the Big Bang, an incredibly hot fireball of fundamental particles — such as protons, neutrons and electrons — expanded and cooled to form the atoms, stars and galaxies we see today".

Where did those fundamental particles come from?

Just wondered... :btime:

Maybe something to do with Heisenberg's uncertainty principle ie the particles may have just winked into existence - but no-one is certain.
 
http://www.astronomerstelegram.org/?read=13410
Betelgeuse is now nearly as faint as (the slightly variable) B2 star Bellatrix .... Betelgeuse is currently the coolest and least luminous yet observed. Since September 2019, the star's temperature has decreased by ~100 K while its luminosity ... has diminished by nearly 25%. At face value .... this implies an increase of the star's radius of ~9%. However, as pointed out by others, the current fainting episode could also arise from expelled, cooling gas/dust partially obscuring the star. The recent changes .... seem best explained from changes in the envelop-outer convection atmosphere of this pulsating, unstable supergiant. If these recent light changes are due to an extra-large amplitude light pulse on the ~420-day period, then the next mid-light minimum is expected during late January/early February, 2020. If Betelgeuse continues to dim after that time then other possibilities will have to be considered. The unusual behavior of Betelgeuse should be closely watched.
 
Has physicist’s gravity theory solved ‘impossible’ dark energy riddle?

Prof Claudia de Rham’s ‘massive gravity’ theory could explain why universe expansion is accelerating

Source: The Guardian online
Date: 25 January, 2020

Cosmologists don’t enter their profession to tackle the easy questions, but there is one paradox that has reached staggering proportions.

Since the big bang, the universe has been expanding, but the known laws of physics suggest that the inward tug of gravity should be slowing down this expansion. In reality, though, the universe is ballooning at an accelerating rate.

Scientists have come up with a name – dark energy – for the mysterious agent that is allowing the cosmos to expand so rapidly and which is estimated to account for 70% of the contents of the universe. But ultimately nobody knows what the stuff actually is.

“It’s the big elephant in the room,” says Prof Claudia de Rham, a theoretical physicist at Imperial College. “It’s very frustrating.”

Change could be afoot. De Rham has pioneered a radical theory that could hold the key to why the universe is expanding faster and faster and explain the nature of dark energy. The theory, known as massive gravity, modifies Einstein’s general relativity, positing that the hypothetical particles (gravitons) that mediate the gravitational force themselves have a mass. In Einstein’s version, gravitons are assumed to be massless.

If gravitons have a mass, then gravity is expected to have a weaker influence on very large distance scales, which could explain why the expansion of the universe has not been reined in.

https://amp-theguardian-com.cdn.amp...y-theory-solved-impossible-dark-energy-riddle
 
Astronomers Have Caught a Rare And Massive 'Accretion Burst' in Our Galaxy

Source: sciencealert.com
Date: 27 January, 2020

Here on Earth, we pay quite a lot of attention to the sun. It's visible to us, after all, and central to our lives. But it is only one of the billions of stars in our galaxy, the Milky Way. It's also quite small compared to other stars – most are at least eight times more massive.

These massive stars influence the structure, shape and chemical content of a galaxy. And when they have exhausted their hydrogen gas fuel and die, they do so in an explosive event called a supernova. This explosion is sometimes so strong that it triggers the formation of new stars out of materials in the dead star's surroundings.

But there's an important gap in our knowledge: astronomers don't yet fully understand how those original massive stars themselves are initially formed. So far, observations have only yielded some pieces of the puzzle.

https://www-sciencealert-com.cdn.am...are-and-massive-accretion-burst-in-our-galaxy
 
Most Detailed Photos Of The Sun Yet

From the new US National Solar Observatory

The US National Solar Observatory’s $344m (£265m) telescope features a four-metre mirror – the world’s largest for a solar telescope – and is located at the 3,000-metre (10,000ft) summit of the Haleakalā volcano on the island of Maui.

Valentin Pillet, the director of the National Solar Observatory, described the telescope, which had been under construction since 2013, as a “formidable technological achievement”. A major challenge was maintaining the telescope’s primary mirror at ambient temperature while it looked directly at the sun – any temperature deviation causes air turbulence that could ruin the image quality. The heat is intense enough to rapidly melt metal at the mirror’s focal point.

Keeping it cool:

Each night, a swimming pool’s worth of ice is emptied into eight tanks. During the day, coolant is routed through the ice tanks and distributed through the observatory by 7.5 miles (12km) of piping. More than 100 air jets are also positioned behind the main mirror.

Incoming light from the sun is deflected from the primary mirror into a chamber of mirrors that sits below the observatory’s dome. Here, the light is bounced from mirror to mirror as it is apportioned between spectrometers, polarimeters and other various other instruments. The observatory’s full suite of instruments, which will allow scientists to measure the magnetic field from the sun’s surface up to its outer atmosphere, will come online later this year.

“The bright features [in the image] … are the foothills of magnetic fields that extend all the way up into the corona and beyond,” said Rimmele. “With the additional instruments that will come online in the next six months, we will be able to measure the magnetic fields from the surface all the way up to 1.5 solar radii.”

The observations could help resolve longstanding mysteries of the sun, including the counterintuitive feature that the corona – the sun’s atmosphere – is heated to millions of degrees when its surface is only 6,000C. Understanding the physics of solar flares and coronal mass ejections could also significantly improve the ability to predict space weather, which can render GPS systems unreliable, take down power grids and knock out communication channels.

Photo/video at link.
 
Back
Top