Stars Archives

January 20, 2023January 20, 2023 by Evan Gough

Binary Dwarf Stars Found Orbiting Each Other Every 20 Hours. They Were Once Almost Touching

Astronomers have spotted a pair of ultra-cool dwarf stars in a tight binary configuration. They rotate around one another in less than one Earth day. Image Credit: NASA/JPL Caltech

A team of astrophysicists has discovered a binary pair of ultra-cool dwarfs so close together that they look like a single star. They’re remarkable because they only take 20.5 hours to orbit each other, meaning their year is less than one Earth Day. They’re also much older than similar systems.

January 18, 2023January 18, 2023 by Evan Gough

The Donut That Used To Be a Star

This sequence of artist's illustrations shows how a black hole can devour a bypassing star. 1) A normal star passes near a supermassive black hole in the center of a galaxy. 2) The star's outer gasses are pulled into the black hole's gravitational field. 3) The star is shredded as tidal forces pull it apart. 4) The stellar remnants are pulled into a donut-shaped ring around the black hole, and will eventually fall into the black hole, unleashing a tremendous amount of light and high-energy radiation. Credit: NASA, ESA, Leah Hustak (STScI)

The death of a star is one of the most dramatic natural events in the Universe. Some stars die in dramatic supernova explosions, leaving nebulae behind as shimmering remnants of their former splendour. Some simply wither away as their hydrogen runs out, billowing into a red giant as they do so.

But others are consumed by behemoth black holes, and as they’re destroyed, the black hole’s powerful gravity tears the star apart and draws its gas into a donut-shaped ring around the black hole.

January 17, 2023January 17, 2023 by Evan Gough

A Black Hole is Savoring its Meal, Feeding on the Same Star Over and Over Again

This illustration shows a glowing stream of material from a star, being devoured and torn to shreds by a supermassive black hole. Credit: NASA/JPL-Caltech

Something extraordinary happens about every 10,000 to 100,000 years in galaxies like the Milky Way. An unwary star approaches the supermassive black hole (SMBH) at the galaxy’s center and is torn apart by the SMBH’s overpowering gravity. Astronomers call the phenomenon a tidal disruption event (TDE.)

Usually, a TDE spells doom for the star as its gas is torn away into the black hole’s accretion ring, causing a bright flaring visible for hundreds of millions of light years. But researchers have found one black hole that’s playing with its food.

January 11, 2023January 11, 2023 by Evan Gough

This Star is Blasting Out a Concentrated Jet of Material at 500 km/s

A team of astronomers was studying the masers around oddball star MWC 349A when they discovered something unexpected: a previously unseen jet of material launching from the star’s gas disk at impossibly high speeds. Image Credit: ALMA (ESO/NAOJ/NRAO), M. Weiss (NRAO/AUI/NSF)

MWC 349A is a star about 3,900 light-years away in the constellation Cygnus. It’s huge, about 38 times as massive as the Sun. It’s actually a binary star and may even be a triple star. It’s an oddball and one of the brightest sources of radio emission in the sky.

One of the star’s unusual features is its natural maser. MWC 349A’s natural maser played a central role in a new discovery: the young star emits a blistering jet of material travelling at 500 km/sec (310 m/sec.) That discovery could help astronomers understand massive stars and their complexity.

December 16, 2022December 16, 2022 by Evan Gough

Are Planets Tidally Locked to Red Dwarfs Habitable? It’s Complicated

habitable exoplanet interstellar message — Artist's impression of the exoplanet Ross 128 b orbiting its red dwarf star. Potetentially habitable rocky worlds like this one are beyond our physical reach. Image Credit: ESO/M. Kornmesser. Public Domain

Astronomers are keenly interested in red dwarfs and the planets that orbit them. Up to 85% of the stars in the Milky Way could be red dwarfs, and 40% of them might host Earth-like exoplanets in their habitable zones, according to some research.

But there are some problems with their potential habitability. One of those problems is tidal locking.

December 3, 2022December 3, 2022 by Evan Gough

How Do Stars Get Kicked Out of Globular Clusters?

Hubble image of Messier 54, a globular cluster located in the Sagittarius Dwarf Galaxy. Credit: ESA/Hubble & NASA

Globular clusters are densely-packed collections of stars bound together gravitationally in roughly-shaped spheres. They contain hundreds of thousands of stars. Some might contain millions of stars.

Sometimes globular clusters (GCs) kick stars out of their gravitational group. How does that work?

December 1, 2022December 1, 2022 by Evan Gough

A Black Hole Consumed a Star and Released the Light of a Trillion Suns

A star is being consumed by a distant supermassive black hole. Astronomers call this a tidal disruption event (TDE). As the black hole rips apart the star, two jets of material moving with almost the speed of light are launched in opposite directions. One of the jets was aimed directly at Earth. Image credit: Carl Knox (OzGrav, ARC Centre of Excellence for Gravitational Wave Discovery, Swinburne University of Technology)

When a flash of light appears somewhere in the sky, astronomers notice. When it appears in a region of the sky not known to host a stellar object that’s flashed before, they really sit up and take notice. In astronomical parlance, objects that emit flashing light are called transients.

Earlier this year, astronomers spotted a transient that flashed with the light of a trillion Suns.

November 30, 2022November 30, 2022 by Evan Gough

It’s Feeding Time For This Baby Star in Orion

This new image of the Orion Nebula produced using previously released data from three telescopes shows two enormous caverns carved out by unseen giant stars that can release up to a million times more light than our Sun. All that radiation breaks apart dust grains there, helping to create the pair of cavities. Much of the remaining dust is swept away when the stars produce wind or when they die explosive deaths as supernovae. Image Credit: ESA/NASA/JPL-Caltech

Young protostars are wrapped in what could be called a womb of gas and dust. The gas and dust nearest to them form a circumstellar disk as the stars grow. The disk is a reservoir of material that the star accretes as it grows.

But these stars don’t feed in a predictable rhythm. Sometimes, they experience feeding frenzies, periods of time they accrete lots of material from the disk at once. When that happens, they flare in bright bursts, “burping” as they absorb more material.

November 14, 2022November 14, 2022 by Evan Gough

New Observations Confirm That a Magnetar has a Solid Surface and No Atmosphere

An artist's impression of a magnetar, a highly magnetic, slowly rotating neutron star. Credit: ESO/L. Calçada

Can a star have a solid surface? It might sound counterintuitive. But human intuition is a response to our evolution on Earth, where up is up, down is down, and there are three states of matter. Intuition fails when it confronts the cosmos.

November 7, 2022November 7, 2022 by Brian Koberlein

Can JWST see Galaxies Made of Primordial Stars?

The distance of first generation stars. Credit: STScI

All stars are composed of mostly hydrogen and helium, but most stars also have measurable amounts of heavier elements, which astronomers lump into the category of “metals.” Our Sun has more metals than most stars because the nebula from which it formed was the remnant debris of earlier stars. These were in turn children of even earlier stars, and so on. Generally, each new generation of stars has a bit more metal than the last. The very first stars, those born from the primordial hydrogen and helium of the cosmos, had almost no metal in them. We’ve never seen one of these primordial stars, but with the power of the Webb and a bit of luck, we might catch a glimpse of them soon.