Stars Archives

July 20, 2023July 20, 2023 by Evan Gough

Star Factories Haven’t Changed Much Over the Entire Age of the Universe

“Sh 2-209” is a rare and large-scale star-forming region in the outer region of the Milky Way Galaxy. It's notable for its low metallicity, a characteristic it shares with the early Universe. Image Credit: NAOJ/Subaru Telescope

The ancient Universe is weird and secretive. Scientists have made laudable progress in uncovering more and more information on how the Universe began and what conditions were like all those billions of years ago. Powerful infrared telescopes, especially the ground-breaking James Webb Space Telescope, have let astronomers study the ancient light from the early Universe and remove some of the secrecy.

One of the mysteries astronomers want to untangle concerns star formation. Has it changed much since the Universe’s early days?

July 13, 2023July 13, 2023 by Matt Williams

How Old is That Star? Ask a Computer

An open cluster of stars known as IC 4651, a stellar grouping that lies at in the constellation of Ara (The Altar). Credit: ESO

When measuring distances in the Universe, astronomers rely on what is known as the “Distance Ladder” – a succession of methods by which distances are measured to objects that are increasingly far from us. But what about age? Knowing with precision how old stars, star clusters, and galaxies are is also paramount to determining how the cosmos has evolved. Thanks to a new machine learning technique developed by researchers from Keele University, astronomers may have established the first rung on a “cosmic age ladder.”

July 10, 2023July 10, 2023 by Brian Koberlein

A Neutron Star is Unwinding a Companion Star

Artist impression of a star being stripped by its companion. Credit: Elisa Schösser

Close binary stars play several important roles in astronomy. For example, Type Ia supernovae, used to measure galactic distances, occur when a neutron star in a binary system reaches critical mass. These stars are also the source of x-ray binaries and microquasars, which help astronomers understand supermassive black holes and active galactic nuclei. But the evolutionary process of close binaries is still not entirely understood. That’s changing thanks in part to a new discovery of a close binary in its intermediate stage.

July 2, 2023July 2, 2023 by Brian Koberlein

A Planet Was Swallowed by a Red Giant, But it Survived

Artist view of Halla as two stars merge to become the star Baekdu. Credit: W. M. Keck Observatory/Adam Makarenko

The Sun is going to kill us. Not anytime soon, but it will kill us. At the moment the Sun keeps itself going by fusing hydrogen into helium and other heavier elements, but in five or so billion years it is going to run out of hydrogen. When that happens, the Sun will make a desperate attempt to keep going by fusing helium. During this period it will swell to a red giant, likely so large that it engulfs the Earth, baking it to a crisp in its diffuse hot atmosphere.

June 27, 2023June 27, 2023 by Evan Gough

A New Way to Measure Distances in the Universe

Image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. Credit: Millennium Simulation Project. Now, the latest FLAMINGO simulation provide more detail about the evolution of the Universe within these structures. — Image of the large-scale structure of the Universe, showing filaments and voids within the cosmic structure. Who knows how many other civilizations might be out there? Credit: Millennium Simulation Project

If we want to understand the Universe, we have to start with its size. Ancient people had no idea there was a Universe the way we understand it now, and no idea of its size. They thought there was the Earth, with everything else rotating around it. It was the only conclusion within reach for a long time.

May 12, 2023May 12, 2023 by Evan Gough

It Took Five Years and A Million Images to Make this Atlas of Stellar Nurseries

This image shows the HH 909 A object in the Chamaeleon constellation. New stars are born in the colourful clouds of gas and dust seen here. The infrared observations underlying this image reveal new details in the star-forming regions that are usually obscured by the clouds of dust. Image Credit: ESO/Meingast et al.

Star formation is an intricate process governed by a swarm of variables, and it all happens behind a thick veil of dust. Astrophysicists understand it to a certain degree. But this is nature, and nature doesn’t give up its intimate secrets without a concentrated effort.

To learn more about the star formation process, astronomers imaged five star-forming regions in the southern hemisphere with the ESO’s VISTA telescope. It took five years and over one million images, and the result is the VISIONS survey.

May 9, 2023May 9, 2023 by Evan Gough

One in Ten Stars Ate a Jupiter (Or Bigger)

This illustration shows a Jupiter-mass exoplanet getting perilously close to its star. Eventually, the star will engulf the planet, something that happens in many stars' lives as they leave the main sequence. Image Credit: C. Carreau / ESA.

In space, cataclysmic events happen to stars all the time. Some explode as supernovae, some get torn apart by black holes, and some suffer other fates. But when it comes to planets, stars turn the tables. Then it’s the stars who get to inflict destruction.

Expanding red giant stars consume and destroy planets that get too close, and a new study takes a deeper look at the process of stellar engulfment.

May 8, 2023May 8, 2023 by Evan Gough

Astronomers Watch a Star Gulp Down One of its Planets

A distant Sun-like star will leave the main sequence behind, ending its life of fusion. Then it'll expand into a red giant, totally destroying its four planets. Image Credit: fsgregs Creative Commons Attribution-Share Alike 3.0 Unported

A star like our Sun only shines the way it does because of its intrinsic balance. Stars are massive, and the inward gravitational pressure from all that mass acts to contain the outward thermal pressure from all the fusion inside the star. They are in equilibrium, or on the main sequence if you like, and the result is a spherical mass of plasma that holds its shape and emits radiation with relative stability for billions of years. Like our Sun.

But eventually, stars teeter over the edge and lose their balance. Stars like our Sun will expand, take on a malevolent red hue, and begin to destroy anything that comes within their grasp.

Like a planet.

May 3, 2023May 3, 2023 by Carolyn Collins Petersen

Astronomers are Starting to Find the Wreckage Left Over from the First Stars in the Universe

Using ESO’s Very Large Telescope (VLT), researchers have found for the first time the fingerprints left by the explosion of the first stars in the Universe. They detected three distant gas clouds whose chemical composition matches what we expect from the first stellar explosions. These findings bring us one step closer to understanding the nature of the first stars that formed after the Big Bang. — This artist’s impression shows a distant gas cloud that contains different chemical elements, illustrated here with schematic representations of various atoms. Using ESO’s Very Large Telescope, astronomers have detected three distant gas clouds whose chemical composition matches what we expect from the explosions of the first stars that appeared in the Universe. These early stars can be studied indirectly by analysing the chemical elements they dispersed into the surrounding environment after they died in supernova explosions. The three distant gas clouds detected in this study are rich in carbon, oxygen, and magnesium, but poor in iron. This is exactly the signature expected from the explosions of the first stars.

The first stars were odd ducks. Nobody’s observed them yet (although astronomers are hopeful JWST might spot them someday) but their ghosts remain. Born more than 13.5 billion years ago, they were very different from most of those we know today. These were massive monsters made mostly of hydrogen and helium. And, when they exploded as supernovae, their “starstuff” got scattered to space. Astronomers have now found the chemical remains of those stars in three distant gas clouds observed by European Southern Observatory’s Very Large Telescope.

April 30, 2023April 30, 2023 by Carolyn Collins Petersen

Be Grateful the Sun Can’t Produce Flares Like This

Artist’s impression of the a massive flare -- called a superflare -- observed on one of the stars in the V1355 Orionis binary star system. The binary companion star is visible in the background on the right. (Credit: NAOJ)

Okay, so we all know that the Sun is heading into solar maximum. That means it’s quite a bit more active, with sunspots, coronal mass ejections, and flares aplenty. But, luckily for us, the Sun isn’t as active as the members of the binary star system V1355 Orionis. One of its stars periodically releases superflares. These are ten times more extensive than the largest solar flare ever recorded on the Sun.