Up to a Third of Stars Ate Some of their Planets

Ultra-short period planets can be engulfed by their stars. They may be responsible for differences in metallicity between sibling stars. Image Credit: NASA, ESA and A. Schaller

In recent years, astronomers have developed techniques to measure the metal content of stars with extreme accuracy. With that capability, astronomers have examined sibling stars to see how their metallicity differs. Some of these co-natal stars have pronounced differences in their metallicity.

New research shows that stars engulfing rocky planets are responsible.

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Webb Reveals a Steam World Planet Orbiting a Red Dwarf

An artist’s conception of the “steam world” GJ 9827 d, shown in the foreground in blue. Astronomers have theorized about these worlds, but this is the first one they've observed. Image credit: NASA, ESA, Leah Hustak (STScI), Ralf Crawford (STScI)

The JWST has found an exoplanet unlike any other. This unique world has an atmosphere almost entirely composed of water vapour. Astronomers have theorized about these types of planets, but this is the first observational confirmation.

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A Star Was Kicked Out of a Globular Cluster by an Intermediate-Mass Black Hole

The M15 Globular Cluster (aka. Great Hercules Cluster). Astronomers suspect the existence of one or more intermediate-mass black holes at its heart. Credit: NASA/ESA/HST
The M15 Globular Cluster (aka. Great Hercules Cluster). Astronomers suspect the existence of one or more intermediate-mass black holes at its heart. Credit: NASA/ESA/HST

Astronomers have solid evidence for the existence of stellar-mass black holes and supermassive black holes. However, evidence for Intermediate Black Holes (IMBHs) is more elusive. Their existence remains hypothetical.

However, study by study, evidence is accumulating for IMBHs. The latest comes from the globular cluster M15, where a fast-moving star suggests the presence of something massive. Could it be an elusive IMBH?

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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