News | February 26, 2020

When Dwarfs Meet Giants and Other True Cosmic Fairy Tales

It’s easy to get lost in fantasy worlds through science-fiction movies and novels, but did you know that some of your favorite fairy-tale characters actually exist in cosmic form? From dwarfs and giants to shape-shifters and buried treasure, the universe is home to a multitude of mystical objects.

White Dwarf Stars

This field of stars is filled with white blobs with fuzzy edges, each a star in the globular cluster called M4. Each star has diffraction spikes that look like a large white X with the star at the center. There are about a dozen large stars that dominate the frame, with smaller ones filling in some of the gaps. A few are cut off by the edge of the image.
This Hubble Space Telescope image of M4, the nearest globular cluster, reveals white dwarf stars that are 12-13 billion years old. Credit: NASA and H. Richer (University of British Columbia)

You’ve probably heard of dwarfs like Happy and Sneezy (or Gimli and Thorin), but it’s unlikely you’re familiar with the space-dwelling dwarfs with names like Sirius B and ASASSN-16oh. White dwarf stars like these are typically about the size of Earth, which is pretty small as far as stars go. They represent one of three final stages of stellar evolution, along with neutron stars and black holes. Each star’s original mass determines which one it will ultimately become. Stars much more massive than the Sun typically become neutron stars or black holes, and lower-mass stars end up as white dwarfs.

A bright ball at the center of the image represents a white dwarf star that glows in pale yellow. Surrounding the star is a disk of material. The disk starts a little distance away from the star and is tilted down to the right. The disk glows in orange closest to the star and fades to grays out to its edges. In the lower left is a blotchy cloud of white gas and dust with a trail leading to the edge of the material disk.
In this artist’s concept, an asteroid (bottom left) breaks apart under the powerful gravity of LSPM J0207+3331, the oldest, coldest white dwarf known to be surrounded by a ring of dusty debris. Scientists think the system’s infrared signal is best explained by two distinct rings composed of dust supplied by crumbling asteroids. Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Our Sun will eventually become a white dwarf after it exhausts its fuel, but don’t worry – we’ve got several billion years to go! Before it is reduced to a white dwarf, it will expand into a red giant, swelling out to encompass Earth’s orbit. But we don’t have to wait billions of years to see stellar giants … some already peek out at us from the cosmic deep.

Giants and Supergiants

The rings of Saturn appear as wide gray blocks that take up nearly the entire image. They are streaked with lines of lighter and darker gray that run nearly vertically, tipped just a bit to the right. There’s a wide gap of black running up the middle of the image. Just to the left of center, embedded in the gray of the rings, there is a small bright spot that is Aldebaran.
The Cassini spacecraft took a series of images on Sept. 9, 2006, as it watched the bright red giant star Aldebaran slip behind Saturn's rings. This view shows the Encke Gap (325 kilometers, or 200 miles wide) and the faint ringlets which share the gap with the embedded moon Pan. Bright Aldebaran is overexposed, creating thin vertical lines on its image. Credit: NASA/JPL/Space Science Institute

The red giant star Aldebaran, located about 65 light-years away, is about 5,000 times bigger than Earth. Our Cassini spacecraft imaged Aldebaran through Saturn’s rings in 2006, but you can see it for yourself during northern winter. Just look for the brightest star in the constellation Taurus.

The left side of this image is dominated by a representation of a blue supergiant. It is a large round star with an electric blue edge and filled with mottled black and blue patches. The star doesn’t fit in the frame of the image; it is cut off on the top, bottom, and left sides, with just over half of its width showing. The Sun is shown as a small smudge of yellow to the right of the blue supergiant. It is 1,000 times smaller. Text at the top of the image reads, “Blue supergiant star; 864,000,000 miles across”. Text near the Sun reads, “Sun; 865,000 miles across.”
This artist’s concept shows a supergiant to scale with the Sun. A supergiant is a star with about 20 times the Sun's mass that still retains its deep hydrogen atmosphere, making it hundreds of times the Sun's diameter. Credit: NASA's Goddard Space Flight Center/S. Wiessinger

Fairy tale giants may be taller than trees, but these supergiant stars can be over 100,000 times “taller” than our entire planet! Supergiant stars are likely becoming more rare as time goes on. While scientists believe they used to be more common, our whole galaxy now contains just a small smattering of supergiants.

This visualization opens on a star field with a bright star at the center of the image. The star then explodes, filling the frame with white light for a moment. As that bright light fades, we see there is a bubble of yellow and red material expanding away from the site of the exploded star.
When a star that is eight times larger than the Sun ends its life, it does not go gentle into that good night. Shifting pressure in its core causes it to collapse and trigger a supernova, as shown here. The initial flash of light, which can outshine the star’s host galaxy, may last only seconds. But the resulting debris that is flung into space can be studied for millennia. Credit: Courtesy of ESA/Hubble/L. Calçada

These massive stars grace the galaxy for a relatively small amount of time. They burn through their fuel extremely quickly – in just a few million years, as opposed to hundreds of billions of years for the smallest stars! Supergiants often end their lives in dramatic explosions called supernovae.

This image has three panels: one on the right, taking up about half the image, and two stacked on the left. In the upper left is a Hubble image of Betelgeuse. The star looks like a glowing ball of yellow light with a bright yellow circle in the center that fades outward to a dark orange. The outer edges appear hazy. Below the image of Betelgeuse are three scale bars. The first shows the size of the star as seen in the Hubble image above. Below that is a scale bar showing the size of Earth’s orbit, which is about a 15% the length of the star’s size. Finally, the last scale bar shows the orbit of Jupiter, which is about 70% as long as the star’s size. The panel on the right shows a black background with many stars of different sizes dotted around the image. The stars of Orion are called out with light white lines drawn between the major stars. An arrow points to one star at the upper left, the location of Betelgeuse.
This is the first direct image of a star other than the Sun, made with NASA's Hubble Space Telescope. Called Alpha Orionis, or Betelgeuse, it is a red supergiant star marking the shoulder of the winter constellation Orion. Credit: Andrea Dupree (Harvard-Smithsonian CfA), Ronald Gilliland (STScI), NASA and ESA

Betelgeuse – the bright, reddish star marking the shoulder of Orion – is nearing the end of its life and has expanded to become a red supergiant star. It is destined to explode as a supernova, which might happen tonight … or within the next few hundred thousand years.

Ghostly Solar Neutrinos

This animation shows a sideways rain of small gray streaks against a black background. The streaks represent neutrinos that fill space.
Elusive particles called neutrinos fly through space in this animation. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

Even an average star like our Sun has some seemingly magical qualities. Each second, it sends billions of phantom-like neutrino particles out into space. They travel almost as fast as light and don’t usually interact with normal matter. Billions of them are zipping harmlessly straight through your body while you read this. Even at night they go through the entire Earth before reaching you!

A gray ball flies across the screen and is magnified when it reaches the middle of the screen. The ball turns blue, orange, and back to gray. Then the ball shrinks back to its original size and continues off the screen.
Animation of a neutrino oscillation, where a neutrino changes characteristics over time. Credit: NASA's Goddard Space Flight Center

But that’s not all … these ghostly particles are shape-shifters, too! Neutrinos can change characteristics over time, morphing between different versions of themselves. Scary!

Buried Treasure in the Heart of the Galaxy

This image of the central region of the Milky Way shows a bright white glow at the center. An irregular line of light pink clouds stretches across the center of the image. Clouds in darker shades of pink and red spread out from that line, with more appearing at the bottom of the image than the top. Seemingly overlaid on these pink clouds are several dark maroon patches of different sizes. The background is studded with tiny white dots which are just some of the stars found in our galaxy.
The center of our Milky Way galaxy is hidden from the prying eyes of optical telescopes by clouds of obscuring dust and gas. But in this stunning vista, NASA’s Spitzer Space Telescope's infrared cameras penetrate much of the dust, revealing the stars of the crowded galactic center region. Credit: NASA, JPL-Caltech, Susan Stolovy (SSC/Caltech) et al.

Extensive clouds of dust enshroud the heart of our Milky Way galaxy, hiding it from our view — at least when it comes to visible light. The dust isn’t as big a problem for infrared light, however, which has allowed us to get a glimpse of our galaxy’s chaotic core thanks to our Hubble and Spitzer space telescopes.

Future missions may peer into the galactic core in search of buried treasure — thousands of planets orbiting distant stars! It will be exciting to see what hidden gems we uncover next.

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