A new image of NGC 1514 from the Gemini North telescope in Hawaii reveals an asymmetric envelope of gas around a two-star system, showing a late stage in the life of a Sun-like star.
The Gemini North telescope, located on Mauna Kea, Hawaii, has captured stunning detail of NGC 1514, known as the Crystal Ball Nebula. The new image, released by NSF NOIRLab, reveals a glowing, asymmetrical envelope of gas surrounding a binary system of two stars. The light captured in the image emerged from the nebula about 1,500 years ago and has only just now reached Earth. (noirlab.edu)
NGC 1514 is located in the constellation Taurus, near the border of the Perseus group. Despite its name, a planetary nebula is not related to planets. It is a historical name that originated in the 18th century, when astronomers saw round, fuzzy objects in telescopes of that time that reminded them of planetary disks. In reality, planetary nebulae are late stages in the lives of low- to intermediate-mass stars.
Not a single star, but a binary system
The nebula was discovered in 1790 by the German-British astronomer William Herschel. The discovery was particularly important because it challenged Herschel’s assumption that nebulae were very distant collections of stars that could not be distinguished individually. In the case of NGC 1514, Herschel noticed a prominent point of light in the center of a faint envelope of gas, and realized that the nebulae around the star were not “stellar in nature,” that is, not simply collections of distant stars.
At first glance, the Crystal Ball Nebula appears to have a single light source at its center. However, according to NOIRLab, the nebula's center is actually home to two stars orbiting each other in a cycle of about nine years. This is the longest cycle known to date for a binary star pair within a planetary nebula. One of the stars, once several times more massive than the Sun, ejected its outer layers in the final stages of its life. Radiation from the exposed core heats and ionizes the gas, causing it to glow.
A gas envelope that tells of the death of a star
When a sun-like star, or a slightly more massive star, nears the end of its life, it does not explode as a supernova. Instead, it gradually sheds its outer layers into space. The ejected material forms an expanding gas cloud, and the hot core remaining at its center illuminates it. In the case of the Crystal Ball Nebula, the gas is estimated to have a temperature of about 15,000 Kelvin, so it emits light in striking colors.
But NGC 1514 is not the smooth, symmetrical nebula you would expect from a classic planetary nebula. The new image shows a bumpy, uneven envelope. The proposed explanation is that the binary system at its center shapes the gas that is emitted. As the two stars orbit each other, their stellar winds affect the envelope of gas, pushing it in different directions and creating the asymmetrical structure seen today.
The image was taken with GMOS, a multi-object spectrograph mounted on the Gemini North telescope. The telescope is one of two telescopes in the Gemini International Observatory, operated by NSF NOIRLab. Gemini North is 8.1 meters in diameter and operates from one of the world's most important astronomical observatories, on the summit of Mauna Kea in Hawaii.
The new image is not just a pretty sight of a celestial object. It provides astronomers with a glimpse into the process by which stars end their lives, and how stellar companions can shape the material they eject. In the case of NGC 1514, what appears to be a cosmic crystal ball is actually a late record of a star's slow death, and how its companion continues to shape the remnants left behind.
Short FAQ:
What is the Crystal Ball Nebula?
The Crystal Ball Nebula is the nickname for NGC 1514, a planetary nebula in the constellation Taurus.
Are planetary nebulae related to planets?
No. It's a historical name. A planetary nebula is formed when a star sheds its outer layers towards the end of its life.
What's special about the new picture?
The image shows in detail the nebula's asymmetric gas envelope, and the influence of the binary system at its center on its shape.
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