For possible life on other planets, the more suns the better

When looking for planets that might support life in our galaxy and beyond, astronomers are looking for conditions that are just right to create the “Goldilocks zone.” This is also called the habitable zone, when a planet is the right distance from its star to have a comfortable temperature and liquid water pooling on its surface.

And as far as we know, life requires water and could exist on planets within the habitable zones of their stars. Now, researchers are proposing that some violent interactions between stars could actually increase the habitable zones for planets orbiting binary, or two-star, systems.

The Gemini North telescope captured an image of a bright new supernova in the Pinwheel Galaxy.

The ring-like shell of the first recorded supernova was captured by the Dark Energy Camera on the Víctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile. The glowing debris marks where a white dwarf star exploded more than 1,800 years ago and was recorded by Chinese astronomers in the year 185.

This artist's illustration shows the large, puffy star Gaia17bpp being partially eclipsed by a dust cloud that surrounds its mysterious smaller companion star.

An image of the Sh2-54 Nebula was taken in infrared light using the European Southern Observatory's VISTA telescope at Paranal Observatory in Chile.

The Gemini North telescope captured a pair of galaxies, NGC 4567 (top) and NGC 4568 (bottom), as they collide. Nicknamed the Butterfly galaxies, they will eventually merge as a single galaxy in 500 million years.

The Hubble Space Telescope captured a spectacular head-on view of the grand design spiral galaxy NGC 3631, located about 53 million light-years away.

This collection of 37 images from the Hubble Space Telescope, taken between 2003 and 2021, includes galaxies that are all hosts to both Cepheid variables and supernovae. They serve as cosmic tools to measure astronomical distance and refine the expansion rate of the universe.

This is the first image of Sagittarius A*, the supermassive black hole at the center of our galaxy, captured by the Event Horizon Telescope project.

Two galaxies, NGC 1512 and NGC 1510, appear to dance in this image from the Dark Energy Camera. The galaxies have been in the process of merging for 400 million years, which has ignited waves of star formation and warped both galaxies.

This illustration shows exocomets orbiting the nearby star Beta Pictoris. Astronomers have detected at least 30 exocomets in the system, which also hosts two exoplanets.

This artist's impression shows a two-star system, with a white dwarf (foreground) and a companion star (background), where a micronova explosion can occur. Although these stellar explosions are smaller than supernovae, they can be intensely powerful.

This sequence of images shows how the solid nucleus (or the "dirty snowball" heart) of Comet C/2014 UN271 was isolated from a vast shell of dust and gas to measure it. Scientists believe the nucleus could be 85 miles across.

The Hubble Space Telescope has captured an image of the most distant star yet: Earendel, which is nearly 13 billion light-years away.

Astronomers have imaged a space phenomena called odd radio circles using the Australian SKA Pathfinder telescope. These space rings are so massive that they measure about a million light-years across -- 16 times bigger than our Milky Way galaxy.

This illustration shows what happens when two large celestial bodies collide in space, creating a debris cloud. NASA's Spitzer Space Telescope saw a debris cloud block the light of the star HD 166191.

Some 4.4 million space objects billions of light-years away have been mapped by astronomers, including 1 million space objects that hadn't been spotted before. The observations were made by the sensitive Low Frequency Array telescope, known as LOFAR.

An unusual triangle shape formed by two galaxies crashing together in a cosmic tug-of-war has been captured in a new image taken by NASA's Hubble Space Telescope. The head-on collision between the two galaxies fueled a star-forming frenzy, creating "the oddball triangle of newly minted stars."

This image of the supernova remnant Cassiopeia A combines some of the first X-ray data collected by NASA's Imaging X-ray Polarimetry Explorer, shown in magenta, with high-energy X-ray data from NASA's Chandra X-Ray Observatory, in blue.

This image shows the Milky Way as viewed from Earth. The star icon shows the position of a mysterious repeating transient. The spinning space object beamed out radiation three times per hour and became the brightest source of radio waves viewable from Earth, acting like a celestial lighthouse.

This Hubble Space Telescope image shows the dwarf galaxy Henize 2-10, which is filled with young stars. The bright center, surrounded by pink clouds, indicates the location of its black hole and areas of star birth.

This image shows the Flame Nebula and its surroundings captured in radio waves.

This artist's impression showcases a red supergiant star in the final year of its life emitting a tumultuous cloud of gas, experiencing significant internal changes before exploding in a supernova.

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Their study was published Wednesday in the Monthly Notices of the Royal Astronomical Society.

Early in their formation, planetary systems are a harsh, tumultuous place. Stars are born in stellar nurseries, where they are clustered together and often result in violent collisions. Baby planets orbit the stars in disks made of gas and dust. Everything that happens is almost at odds with enabling planetary systems to form.

An Earth-size planet inside, within and outside its star's habitable zone.

But this may actually help the habitable zone, according to astronomers at the University of Sheffield. Bethany Wootton, an undergraduate student, and Richard Parker, a Royal Society Dorothy Hodgkin Fellow, developed a model to look at how the habitable zone changes around binary systems.

Astronomers believe that a third of the star systems in our galaxy, the Milky Way, are made up of two or more stars. The number increases when they consider younger stars.

This image shows an artist's impression of the planet's surface. Credit: ESO/M. Kornmesser

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In a system with more than one star, the size of habitable zone for the planet is determined by the stars’ distance from each other. If they are far apart, each has its own habitable zone, based on the radiation from that star. But if the stars are close, their habitable zones are also closer to each other and provide a larger, warmer zone. The larger the zone, the better chance for a planet to find itself in the right spot to support life.

A diagram of two stars in a binary system, before and after an encounter with a third passing star.

The researchers used simulations to look at clusters of young stars in stellar nurseries, which can contain 350 binaries. Out of those 350, 20 are nudged closer together because of the movements of a third star. And then their habitable zones would expand.

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A few of the binary star systems even had overlapping habitable zones, which would increase the chance of a planet orbiting either or both stars to be in the right spot.

“The search for life elsewhere in the universe is one of the most fundamental questions in modern science, and we need every bit of evidence we can find to help answer it,” Wootton said in a statement. “Our model suggests that there are more binary systems where planets sit in Goldilocks zones than we thought, increasing the prospects for life. So those worlds beloved of science fiction writers – where two suns shine in their skies above alien life – look a lot more likely now.”

The quest for the habitable zone also motivated the creation of the Habitable Zone Planet Finder, an astronomical spectrograph that can measure infrared signals from nearby stars and find planets that could support water on their surface. The HPF is at the University of Texas at Austin’s McDonald Observatory and will seek out low-mass planets around cool red dwarf stars, which are known to host rocky planets. The new planet finder began operating in February.