metallicity Archives

April 30, 2024April 30, 2024 by Evan Gough

Binary Stars Form in the Same Nebula But Aren’t Identical. Now We Know Why.

This artist’s impression illustrates a binary pair of giant stars. Despite being born from the same molecular cloud, astronomers often detect differences in binary stars’ chemical compositions and planetary systems. Image Credit: NOIRLab/NSF/AURA/J. da Silva (Spaceengine)/M. Zamani

It stands to reason that stars formed from the same cloud of material will have the same metallicity. That fact underpins some avenues of astronomical research, like the search for the Sun’s siblings. But for some binary stars, it’s not always true. Their composition can be different despite forming from the same reservoir of material, and the difference extends to their planetary systems.

New research shows that the differences can be traced back to their earliest stages of formation.

April 30, 2024April 30, 2024 by Evan Gough

Astronomers Think They’ve Found Examples of the First Stars in the Universe

An artist's illustration of some of the Universe's first stars. Called Population 3 stars, they formed a few hundred million years after the Big Bang. Image Credit: By NASA/WMAP Science Team - https://www.nasa.gov/vision/universe/starsgalaxies/fuse_fossil_galaxies.html (image link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=1582286

When the first stars in the Universe formed, the only material available was primordial hydrogen and helium from the Big Bang. Astronomers call these original stars Population Three stars, and they were extremely massive, luminous, and hot stars. They’re gone now, and in fact, their existence is hypothetical.

But if they did exist, they should’ve left their fingerprints on nearby gas, and astrophysicists are looking for it.

April 17, 2024April 17, 2024 by Evan Gough

The Milky Way’s Most Massive Stellar Black Hole is Only 2,000 Light Years Away

This image shows the locations of the first three black holes discovered by ESA's Gaia mission in the Milky Way. Gaia Black Hole 1 (BH1) is located just 1560 light-years away from us in the direction of the constellation Ophiuchus; Gaia BH2 is 3800 light-years away in the constellation Centaurus; Gaia BH3 is in the constellation Aquila, at a distance of 1926 light-years from Earth. In galactic terms, these black holes reside in our cosmic backyard. Image Credit: ESA/Gaia/DPAC. Licence CC BY-SA 3.0 IGO

Astronomers have found the largest stellar mass black hole in the Milky Way so far. At 33 solar masses, it dwarfs the previous record-holder, Cygnus X-1, which has only 21 solar masses. Most stellar mass black holes have about 10 solar masses, making the new one—Gaia BH3—a true giant.

April 12, 2024April 12, 2024 by Evan Gough

The Brightest Gamma Ray Burst Ever Seen Came from a Collapsing Star

This artist's visualization of GRB 221009A shows the narrow relativistic jets (emerging from a central black hole) that gave rise to the gamma-ray burst (GRB) and the expanding remains of the original star ejected via the supernova explosion. Credit: Aaron M. Geller / Northwestern / CIERA / IT Research Computing and Data Services

After a journey lasting about two billion years, photons from an extremely energetic gamma-ray burst (GRB) struck the sensors on the Neil Gehrels Swift Observatory and the Fermi Gamma-Ray Space Telescope on October 9th, 2022. The GRB lasted seven minutes but was visible for much longer. Even amateur astronomers spotted the powerful burst in visible frequencies.

It was so powerful that it affected Earth’s atmosphere, a remarkable feat for something more than two billion light-years away. It’s the brightest GRB ever observed, and since then, astrophysicists have searched for its source.

April 3, 2024April 3, 2024 by Evan Gough

The Large Magellanic Cloud isn’t Very Metal

This image shows the Large and Small Magellanic Clouds in the sky over the ESO's Paranal Observatory and the four telescopes of the VLT. Image Credit: By ESO/J. Colosimo - http://www.eso.org/public/images/potw1511a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=38973313

The Large Magellanic Cloud (LMC) is the Milky Way’s most massive satellite galaxy. Because it’s so easily observed, astronomers have studied it intently. They’re interested in how star formation in the LMC might have been different than in the Milky Way.

A team of researchers zeroed in on the LMC’s most metal-deficient stars to find out how different.

March 21, 2024March 21, 2024 by Evan Gough

One in Twelve Stars Ate a Planet

When a star eats a planet, it changes the star's metallicity. New research based on co-natal stars shows that one in twelve stars have eaten at least one planet. Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA/M. Garlick/M. Zamani

That stars can eat planets is axiomatic. If a small enough planet gets too close to a large enough star, the planet loses. Its fate is sealed.

New research examines how many stars eat planets. Their conclusion? One in twelve stars has consumed at least one planet.

January 4, 2024January 4, 2024 by Evan Gough

This Globular Cluster is Plunging Toward the Milky Way’s Centre

The galactic cenre is dominated by powerful tidal forces. What happens to globular clusters that get too close? Image Credit: Spitzer Space Telescope/NASA/JPL-Caltech

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.

December 19, 2023December 19, 2023 by Evan Gough

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?

November 23, 2023November 23, 2023 by Evan Gough

Adolescent Galaxies are Incandescent and Contain Unexpected Elements

Light from 23 distant galaxies, identified with red rectangles in the Hubble Space Telescope image at the top, were combined to capture incredibly faint emission from eight different elements, which are labelled in the JWST spectrum at the bottom. Although scientists regularly find these elements on Earth, astronomers rarely, if ever, observe many of them in distant galaxies, especially nickel. Image Credit: Aaron M. Geller, Northwestern, CIERA + IT-RCDS

If the Universe has adolescent galaxies, they’re the ones that formed about 2 to 3 billion years after the Big Bang. New research based on the James Webb Space Telescope shows that these teenage galaxies are unusually hot. Not only that, but they contain some unexpected chemical elements. The most surprising element found in these galaxies is nickel.

September 21, 2023September 21, 2023 by Brian Koberlein

We Can't See the First Stars Yet, but We Can See Their Direct Descendants

This artist’s impression shows a Population III star that is 300 times more massive than our Sun exploding as a pair-instability supernova. Credit: NOIRLab/NSF/AURA/J. da Silva/Spaceengine

If you take a Universe worth of hydrogen and helium, and let it stew for about 13 billion years, you get us. We are the descendants of the primeval elements. We are the cast-off dust of the first stars, and many generations of stars after that. So our search for the first stars of the cosmos is a search for our own history. While we haven’t captured the light of those first stars, some of their direct children may be in our own galaxy.