In the beginning, the Universe was so hot and so dense that light could not travel far. Photons were emitted, scattered, and absorbed as quickly as the photons in the heart of the brightest stars. But in time the cosmos expanded and cooled to the point that it became transparent, and the birthglow of the Big Bang could traverse space and time for billions of years. We still see it as the microwave cosmic background. As the Universe expanded it grew dark, filled only with warm clouds of hydrogen and helium. In time those clouds collapsed to form the first stars, and light again filled the heavens.
Continue reading “Nancy Grace Roman Could Find the First Stars in the Universe”Is this the Lightest Black Hole or Heaviest Neutron Star?
About 40,000 light-years away, a rapidly spinning object has a companion that’s confounding astronomers. It’s heavier than the heaviest neutron stars, yet at the same time, it’s lighter than the lightest black holes. Measurements place it in the so-called black hole mass gap, an observed gap in the stellar population between two to five solar masses. There appear to be no neutron stars larger than two solar masses and no black holes smaller than five solar masses.
Continue reading “Is this the Lightest Black Hole or Heaviest Neutron Star?”Astronomers See Massive Stars Forming Together in Multiple Star Systems
All stars form in giant molecular clouds of hydrogen. But some stars are extraordinarily massive; the most massive one we know of is about 200 times more massive than the Sun. How do these stars gain so much mass?
Part of the answer is that they form in multiple star systems.
Continue reading “Astronomers See Massive Stars Forming Together in Multiple Star Systems”A Giant Star is Fading Away. But First, it Had an Enormous Eruption
About 16,000 light-years away, a massive star experienced an unusual dimming event. This can happen in binary stars when one star passes in front of the other. It can also be due to intrinsic reasons like innate variability. But this star dimmed by as much as one-third, a huge amount.
What happened?
Continue reading “A Giant Star is Fading Away. But First, it Had an Enormous Eruption”This Globular Cluster is Plunging Toward the Milky Way’s Centre
Globular clusters (GCs) are spherical groups of stars held together by mutual gravity. Large ones can have millions of stars, and the stars tend to be older and have lower metallicity. The Milky Way contains more than 200 globulars, possibly many more, and most of them are in the galaxy’s halo, the outer reaches of the galaxy.
But they’re not all in the halo, and astronomers are keen to find ones nearest the galactic centre. Now, researchers have found one GC that’s plunging toward the Milky Way’s Centre.
Continue reading “This Globular Cluster is Plunging Toward the Milky Way’s Centre”Can Webb Find the First Stars in the Universe?
The Universe’s very first stars had an important job. They formed from the primordial elements created by the Big Bang, so they contained no metals. It was up to them to synthesize the first metals and spread them out into the nearby Universe.
The JWST has made some progress in finding the Universe’s earliest galaxies. Can it have the same success when searching for the first stars?
Continue reading “Can Webb Find the First Stars in the Universe?”Could There Be a Black Hole Inside the Sun?
It’s a classic tale of apocalyptic fiction. The Sun, our precious source of heat and light, collapses into a black hole. Or perhaps a stray black hole comes along and swallows it up. The End is Nigh! If a stellar-mass black hole swallowed our Sun, then we’d only have about 8 minutes before, as the kids say, it gets real. But suppose the Sun swallowed a small primordial black hole? Then things get interesting, and that’s definitely worth a paper on the arXiv.
Continue reading “Could There Be a Black Hole Inside the Sun?”Ancient Stars Could Make Elements With More Than 260 Nucleons
The first stars of the Universe were monstrous beasts. Comprised only of hydrogen and helium, they could be 300 times more massive than the Sun. Within them, the first of the heavier elements were formed, then cast off into the cosmos at the end of their short lives. They were the seeds of all the stars and planets we see today. A new study suggests these ancient progenitors created more than just the natural elements.
Continue reading “Ancient Stars Could Make Elements With More Than 260 Nucleons”How Do Superflares Get So Powerful?
We live with a star that sends out flares powerful enough to disrupt things here on Earth. Telecommunications, power grids, even life itself, are affected by strong solar activity. But, the Sun’s testy outbursts are almost nothing compared to the superflares emitted by other stars. Why do flares happen? And what’s going on at distant stars to ramp up the power of their flares?
Continue reading “How Do Superflares Get So Powerful?”Three Baby Stars Found at the Heart of the Milky Way
The core of our Milky Way is buzzing with stars. Recently astronomers reported that it contains at least one ancient star that formed outside our galaxy. Now, an international research team reports finding a grouping of very young ones there, as well. Their presence upends ideas about star birth in that densely packed region of space.
Continue reading “Three Baby Stars Found at the Heart of the Milky Way”