Tag Archives: ESO

A Ring of Fire

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Fine Ring NebulaThis rather unusual planetary nebula is the Fine Ring Nebula. Planetary nebulae form from dying stars when they have expanded into a red giant phase and then eject a shell of gas as they evolve into the next phase of their stellar evolution, white dwarfs. Most planetary nebulae are either spherical or elliptical in shape, or are bipolar (featuring two symmetric lobes of material), but the Fine Ring Nebula looks like an almost perfectly circular ring. Astronomers believe that this unusually shaped planetary nebula was formed from a binary system. The interaction between the primary star and its orbiting companion shapes the ejected material.

The stellar object at the center of the Fine Ring Nebula does appear to be a binary system, orbiting with a period of 2.9 days. Observations suggest that the binary pair is almost perfectly face-on from our vantage point, implying that the planetary nebula’s structure is aligned in the same way. Our point of view looks down on the torus (doughnut shape) of ejected material, leading to the strikingly circular ring shape in the image.

Image Credit: ESO

NGC 300

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ngc 300NGC 300 is a spiral galaxy in the constellation Sculptor. At one time, it was thought that NGC 300 was a part of a galaxy cluster know as th eSculptor Group. However, recent measurements show that it is closer to us in the relatively empty space between our Local Group and the Sculptor Group. It’s about 94,000 light-years in diameter, somewhat smaller than the Milky Way

Image Credit: ESO

The Milky Way

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milkwayThis 360-degree panorama covers all of the southern and northern celestial hemispheres. The plane of our Milky Way Galaxy, which we see edge-on from Earth, is the luminous band across the image. The projection used in the picture puts the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image. It’s almost as if we were looking at the Milky Way from the outside because the solar system is near the galactic rim. From our vantage point the general components of our spiral galaxy come clearly into view, including its disc as well as the central bulge and nearby satellite galaxies.

Image Credit: ESO / S. Brunier

A Dwarf (Helium) Flasher

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White Dwarf ResurrectionPay no attention to the bright star in the center of the picture. The really interesting stellar object in the frame is that blob of red near the bottom. It’s a small white dwarf undergoing a helium flash.

Normally, the white dwarf stage is the end of the life cycle of a low-mass star, but in some rare cases, a star reignites in a helium flash and expands to its previous red giant state. When this happens, huge amounts of gas and dust are ejected before the star shrinks to become a white dwarf again.

A helium flash is a dramatic and short-lived series of events, and this star—Sakurai’s Object, named for the Japanese amateur astronomer who discovered it—has allowed astronomers a rare opportunity to study a helium flash as it occurred.

Image Credit: ESO

Partly Cloudy, For Now

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The Dark Cloud Lupus 4Lupus 4, a spider-shaped blob of gas and dust, blots out background stars like a dark cloud on a moonless night. Although dark and gloomy for now, dense pockets of material within such clouds are where new stars form and where they will later burst into radiant life. Lupus 4 is about 400 light-years away, straddling the constellations of Lupus (The Wolf) and Norma (The Carpenter’s Square).

Image Credit: ESO

Visions of Future Past

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ngc2207Over next couple of billion years, these two spiral galaxies will end up in a complete galactic merger—the two galaxies will become a single, larger one. They’re about 150 million light-years away in the constellation of Canis Major (the Great Dog), so what we can see now is what was happening 150 million years ago.

The gravitational attraction of NGC 2207, the larger of the pair, is already stirring things up throughout its smaller partner, distorting IC 2163’s shape and throwing stars and gas into long streamers that extend over 100,000 light-years. However, most of the space between stars in a galaxy is empty. When these galaxies collide, almost none of the stars in them will crash into another star.

This 150 million old image is a vision of the Milky Way’s future. About the time NGC 2207 and IC 2163 have finished their merger, the Milky Way will begin colliding with the Andromeda Galaxy.

Image Credit: ESO

M87

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The halo of galaxy Messier 87The giant elliptical galaxy Messier 87 is surrounded by a huge halo. An increase in brightness in the top-right part of this halo and the motion of planetary nebulae in the galaxy are the last remaining signs of a medium-sized galaxy that collided with M87.

This wide field image also contains many other galaxies forming the Virgo Cluster, of which Messier 87 is the largest member. The two galaxies at the edge of the top right of the frame are nicknamed “the Eyes.”

Image Credit: ESO

A Different Kind of Sunspot

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Here’s the European Southern Observatory’s description of this animation—

Spots on extreme horizontal branch stars (right) appear to be quite different from the dark sunspots on our own Sun (left), but both are caused by magnetic fields. The spots on these hot, extreme stars are brighter and hotter than the surrounding stellar surface, unlike on the Sun where we see spots as dark stains on the solar surface that are cooler than their surroundings. The spots on extreme horizontal branch stars are also significantly larger than sunspots, covering up to a quarter of the star’s surface. While sunspots vary in size, a typical size is around an Earth-size planet, 3000 smaller than a giant spot on an extreme horizontal branch star.

Video Credit: ESO

Go here for information about extreme horizontal branch stars.

The Medusa Nebula

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ESO’s Very Large Telescope images the Medusa NebulaESO’s Very Large Telescope in Chile captured this image of the Medusa Nebula (also known Abell 21 and Sharpless 2-274). As the star at the heart of this nebula made its final transition into the final stage of its existence, it blew off its outer layers into space, forming this colorful cloud. The Sun will go through a similar process in a few billion years.

Image Credit: ESO