stellar evolution Archives

April 15, 2024April 15, 2024 by Mark Thompson

Baby Stars Discharge “Sneezes” of Gas and Dust

The baby star at the center surrounded by a bright disk called a protostellar disk. Spikes of magnetic flux, gas, and dust in blue. Researchers found that the protostellar disk will expel magnetic flux, gas, and dust—much like a sneeze—during a star's formation.

I’m really not sure what to call it but a ‘dusty sneeze’ is probably as good as anything. We have known for some years that stars surround themselves with a disk of gas and dust known as the protostellar disk. The star interacts with it, occasionally discharging gas and dust regularly. Studying the magnetic fields revealed that they are weaker than expected. A new proposal suggests that the discharge mechanism ‘sneezes’ some of the magnetic flux out into space. Using ALMA, the team are hoping to understand the discharges and how they influence stellar formation.

April 9, 2024April 9, 2024 by Evan Gough

What Happens to Solar Systems When Stars Become White Dwarfs?

In this artist's illustration, lumps of debris from a disrupted planetesimal are irregularly spaced on a long and eccentric orbit around a white dwarf. Individual clouds of rubble intermittently pass in front of the white dwarf, blocking some of its light. Because of the various sizes of the fragments in these clumps, the brightness of the white dwarf flickers in a chaotic way. Credit: Dr Mark Garlick/The University of Warwick

In a couple billion years, our Sun will be unrecognizable. It will swell up and become a red giant, then shrink again and become a white dwarf. The inner planets aren’t expected to survive all the mayhem these transitions unleash, but what will happen to them? What will happen to the outer planets?

March 31, 2024March 31, 2024 by Mark Thompson

It Takes a Supercomputer to Properly Simulate a Neutron Star’s Surface

Neutron stars, the remains of massive stars that have imploded and gone supernova at the end of their life, can still create massive flares. These incredible bursts of energy release X-rays that propagate through space. It is a complex process to simulate but astronomers have turned to a supercomputer to help. Modelling the twisting magnetic fields, the interaction with gas and dust, the surface of flaring neutron stars has been revealed in incredible 3D.

March 29, 2024March 29, 2024 by Mark Thompson

Neutron Stars are Jetting Material Away at 40% the Speed of Light

It’s a well known fact that black holes absorb anything that falls into them. Often before material ‘vanishes’ inside it forms into an accretion disk around them. Like the progenitor stars, the black holes have powerful magnetic fields and these can generate jets that blast away from the black hole. A similar process occurs in neutron stars that are orbiting other stars and recent observations holes have shown that some material in the jets travel at speeds 35-40% the speed of light.

March 12, 2024March 14, 2024 by Mark Thompson

Black Holes are Tearing Stars Apart All Around Us

Illustration of star remnants after it is shredded by a supermassive black hole. Credit: NASA

Galaxy NGC3799 lies around 16 million light years from Earth. Any event observed today within that galaxy took place 16 million years ago. One such event was observed in February 2023 when a surge in brightness in the core was followed by a rapid dimming. The observations that followed revealed that the event was a star being torn apart by a supermassive black hole at the heart of the galaxy. This is not the first time such an event has been observed but it is the first to be within our galactic backyard suggesting it may be more common that first thought.

March 6, 2024March 6, 2024 by Brian Koberlein

Webb Sees a System That Just Finished Forming its Planets

An artistic impression adapted to highlight gas dispersing from a planet-forming disk. Credit: ESO/M. Kornmesser

Nearly 5 billion years ago a region of gas gravitationally collapsed within a vast molecular cloud. At the center of the region, the Sun began to form, while around it formed a protoplanetary disk of gas and dust out of which Earth and the other planets of the solar system would form. We know this is how the solar system began because we have observed this process in systems throughout the galaxy. But there are details of the process we still don’t understand, such as why gas planets are relatively rare in our system.

February 13, 2024February 13, 2024 by Evan Gough

Dying Stars Could Have Completely New Habitable Zones

As stars like our Sun age, their habitable zones shift, and they can warm planets that were once frozen. Image Credit: ESO/L. Calçada

Aging stars that become red giants increase their luminosity and can wreak havoc on planets that were once in the star’s habitable zones. When the Sun becomes a red giant and expands, its habitable zone will move further outward, meaning Earth will likely lose its atmosphere, its water, and its life. But for planets further out, their time in the habitable zone will just begin.

Is there enough time for life to arise on these newly habitable planets?

February 6, 2024February 6, 2024 by Mark Thompson

Astronomers See 18 Examples of Stars Getting Torn Apart by Black Holes

MIT scientists have identified 18 new tidal disruption events (TDEs) — extreme instances when a nearby star is tidally drawn into a black hole and ripped to shreds. The detections more than double the number of known TDEs in the nearby universe. Credits:Credit: Courtesy of the researchers, edited by MIT News

Black holes have always held a special fascination for me ever since I was a geeky kid looking up at the stars. Their intense forces are the stuff of science fiction and can tear a star to pieces. This process is violent and can send bursts of electromagnetic radiation across the Cosmos. A paper recently published announces the discovery of 18 new tidal events just like this, doubling the number of identified shredded stars.

January 28, 2024January 28, 2024 by Brian Koberlein

New Types of Hidden Stars Seen for the First Time

Artist’s impression of a cloud of smoke and dust being thrown out by a red giant star. Credit: Philip Lucas/University of Hertfordshire

In the early days of telescopic astronomy, you could only focus on one small region of the sky at a time. Careful observations had to be done by hand, and so much of the breakthrough work centered around a particular object in the sky. A nebula or galaxy, quasar or pulsar. But over the years we’ve been able to build telescopes capable of capturing a wide patch of sky all at once, and with automation, we can now map the entire sky. Early sky surveys took years to complete, but many modern sky surveys can look for changes on the order of weeks or days. This ability to watch for changes across the sky is changing the way we do astronomy, and it is beginning to yield some interesting results. As a case in point, an infrared sky survey is revealing hidden stars we hadn’t noticed before.

January 2, 2024January 2, 2024 by Mark Thompson

Simulation Perfectly Matches What We See When Neutron Stars Collide

Numerical simulation of the resulting ejecta material of two merging neutron stars. Red colors refer to ejected material with a high fraction of neutrons which will appear typically redder than blue material that contains a higher fraction of protons. © I. Markin (University of Potsdam)

There are many mysteries in the world of astronomy and a fair number relate to the processes during the end of the life of a super massive star. Throw in the complexity of collisions and you have a real head scratching problem on your hands. In 2017 colliding neutron stars were detected and the data has allowed a new simulation to be tested with predictions beautifully matching observation.