Stars Archives

October 9, 2020October 9, 2020 by Evan Gough

Just How Bad are Superflares to a Planet’s Habitability?

Star’s can be full of surprises; some of them nasty. While our own Sun appears pretty placid, science has shown us that’s not the case. Coronal mass ejections and solar flares are the Sun’s angry side.

And the Sun has only a mild case of the flares, compared to some other stars.

October 8, 2020October 8, 2020 by Evan Gough

Planets Don’t Wait for Their Star to Form First

The young star IRS 63 has baby planets forming around it while the star itself is still forming. Image Credit: Segura-Cox et al, 2020.

It looks like we may have to update our theories on how stars and planets form in new solar systems. A team of astronomers has discovered young planets forming in a solar system that’s only about 500,000 years old. Prior to this discovery, astronomers thought that stars are well into their adult life of fusion before planets formed from left over material in the circumstellar disk.

Now, according to a new study, it looks like planets and stars can form and grow up together.

October 2, 2020October 2, 2020 by Paul M. Sutter

What Decides the Shape of Planetary Nebulae? Whatever’s Orbiting a Star When it Dies

This Picture of the Week from the NASA/ESA Hubble Space Telescope shows NGC 5307, a planetary nebula which lies about 10000 light years from Earth. It can be seen in the constellation Centaurus (The Centaur), which can be seen primarily in the southern hemisphere. A planetary nebula is the final stage of a Sun-like star. As such, planetary nebulae allow us a glimpse into the future of our own Solar System. A star like our Sun will, at the end of its life, transform into a red giant. Stars are sustained by the nuclear fusion that occurs in their core, which creates energy. The nuclear fusion processes constantly try to rip the star apart. Only the gravity of the star prevents this from happening. At the end of the red giant phase of a star, these forces become unbalanced. Without enough energy created by fusion, the core of the star collapses in on itself, while the surface layers are ejected outward. After that, all that remains of the star is what we see here: glowing outer layers surrounding a white dwarf star, the remnants of the red giant star’s core. This isn’t the end of this star’s evolution though — those outer layers are still moving and cooling. In just a few thousand years they will have dissipated, and all that will be left to see is the dimly glowing white dwarf.

Planetary nebulae are some of the most beautiful objects in the galaxy, spanning a variety of shapes and sizes. They’re created in the death throes of stars like the sun, and new research sheds light into how they get their distinctive and unique shapes. The answer: anything unlucky enough to orbit that dying star.

September 22, 2020September 22, 2020 by Paul M. Sutter

If dark matter is a particle, it should get inside red giant stars and change the way they behave

This artist’s impression shows the red supergiant star. Using ESO’s Very Large Telescope Interferometer, an international team of astronomers have constructed the most detailed image ever of this, or any star other than the Sun. Credit: ESO/M. Kornmesser

Dark matter makes up the vast majority of matter in the universe, but we can’t see it. At least, not directly. Whatever the dark matter is, it must interact with everything else in the universe through gravity, and astronomers have found that if too much dark matter collects inside of red giant stars, it can potentially cut their lifetimes in half.

September 18, 2020September 18, 2020 by Evan Gough

Searching for Phosphorus in Other Stars

A Southwest Research Institute scientist has identified stellar phosphorus as a probable marker in narrowing the search for life in the cosmos. Stars with phosphorus levels similar to the Sun are considered more likely to host rocky planets with the potential to host life as we know it. Image Credit: NASA/JPL-Caltech

The Search for Life can be a lot messier than it sounds. The three words make a nice, tidy title, but what it entails is extraordinarily difficult. How, in this vast galaxy, can we find life and the planets or moons that might host it? We’re barely at the point of either discovering or ruling out other life in our own Solar System.

Finding it somewhere else in the galaxy, even in our own interstellar neighbourhood, is a task so daunting it can be hard to comprehend.

So any time scientists think they’ve found something that can give them an edge in their near-impossible task, it deserves to be talked about.

September 8, 2020September 8, 2020 by Evan Gough

The Strange, Misshapen Orbits of Planet-Forming Disks in a Triple-Star System

ALMA images of the planet-forming disk with misaligned rings around triple star system GW Orionis. The image on the right is made with ALMA data taken in 2017 from Bi et al. The image on the left is made with ALMA data taken in 2018 from Kraus et al. Credit: ALMA (ESO/NAOJ/NRAO), S. Kraus & J. Bi; NRAO/AUI/NSF, S. Dagnello

Whatever we grow up with, we think of as normal. Our single solitary yellow star seems normal to us, with planets orbiting on the same, aligned ecliptic. But most stars aren’t alone; most are in binary relationships. And some are in triple-star systems.

And the planet-forming disks around those three-star systems can exhibit some misshapen orbits.

August 13, 2020August 14, 2020 by Brian Koberlein

Fastest Star Ever Seen is Moving at 8% the Speed of Light

This artist's impression shows part of the orbit of one of the stars very close to the supermassive black hole at the centre of the Milky Way. Analysis of data from ESO’s Very Large Telescope and other telescopes suggests that the orbits of these stars may show the subtle effects predicted by Einstein’s general theory of relativity. There are hints that the orbit of this star, called S2, is deviating slightly from the path calculated using classical physics. This close-up of the orbit of star S2 shows how the path of the star is slightly different when it passed the same part of its orbit for the second time, 15 years later, due to the effects of general relativity.

In the center of our galaxy, hundreds of stars closely orbit a supermassive black hole. Most of these stars have large enough orbits that their motion is described by Newtonian gravity and Kepler’s laws of motion. But a few orbits so closely that their orbits can only be accurately described by Einstein’s general theory of relativity. The star with the smallest orbit is known as S62. Its closest approach to the black hole has it moving more than 8% of light speed.

July 21, 2020July 21, 2020 by Evan Gough

Supercomputer Simulation Shows a Supernova 300 Days After it Explodes

A 2-D snapshot of a pair-instability supernovae as the explosion waves are about to break through the star's surface. The tiny disturbances represent fluid instability - in a region where different elements interact and mix. Image Credit: ASIAA/Ken Chen

The answers to many questions in astronomy are hidden behind the veil of deep time. One of those questions is around the role that supernovae played in the early Universe. It was the job of early supernovae to forge the heavier elements that were not forged in the Big Bang. How did that process play out? How did those early stellar explosions play out?

A trio of researchers turned to a supercomputer simulation to find some answers.

July 14, 2020July 14, 2020 by Evan Gough

1 in 10 Red Giants are Covered in Spots, and They Rotate Surprisingly Quickly

Artist's impression of a red giant star. If the star is in a binary pair, what happens to its sibling? Credit:NASA/ Walt Feimer

Sunspots are common on our Sun. These darker patches are cooler than their surroundings, and they’re caused by spikes in magnetic flux that inhibit convection. Without convection, those areas cool and darken.

Lots of other stars have sunspots, too. But Red Giants (RGs) don’t. Or so astronomers thought.

A new study shows that some RGs do have spots, and that they rotate faster than thought.

July 7, 2020July 7, 2020 by Evan Gough

Betelgeuse Probably Dimmed Because of Enormous Starspots

An artist's impression of Betelgeuse. Its surface is covered by large star spots, which reduce its brightness. During their pulsations, such stars regularly release gas into their surroundings, which condenses into dust. Image Credit: MPIA graphics department

A few months ago we all watched as Betelgeuse dimmed. Between October 2019 and 22nd of February 2020 the star’s brightness dropped by a factor of about three. It went from magnitude 0.5, and from being the tenth-brightest star in the sky, to magnitude 1.7.

Naturally, we all wondered what was happening. Would it go supernova? Even though that was extremely unlikely, how could we help but wonder?