The Hubble Telescope found a cosmic bubble for its birthday by releasing a spectacular image of the Bubble Nebula. The Hubble Telescope team took the anniversary image to commemorate 26 years in orbit.
The multinational NASA/ESA Hubble Space Telescope team captured the vast Bubble Nebula by making a composite of four images, using the Wide Field Camera 3 or WFC3. While the Hubble Telescope has taken partial images of the fascinating formation in the past, this represents the first time the Bubble Nebula has been captured in a single image.
The Bubble Nebula or NGC 7635 is located within the constellation known as Cassiopeia, about 8,000 light years away from Earth. A media release from the Hubble Telescope team describes the image as a “gigantic cosmic soap bubble” and the description is apt. However, in reality the vast formation glows from the inside out, lit up by a star that burns inside a cloud of gas and dust. The vivid blue color that illuminates the Hubble Telescope image comes from intense ultraviolet radiation of the star inside the cloud.
The Bubble Nebula lives up to its name with a markedly rounded and nearly symmetrical shape, as seen in the Hubble Telescope image. That rounding effect comes about because it lies in the path of a stellar wind originating from a bright star nearby, which can be seen to the upper left of the image. A stellar wind is a blast of gas that comes from the upper atmosphere of a star. The more massive the star, the more gas that is ejected. The Bubble Nebula lies close to the star known as SAO 20575, which has a mass 10 to 20 times that of the sun.
A stellar wind acts much the same way as the movement of the air that we call wind here on Earth. The Bubble Nebula, like the other objects near SAO 20575, is experiencing the pressure of 100,000 kilometer-an-hour stellar winds. Essentially, the stellar wind is blowing a blue bubble of interstellar material. The sphere of Bubble Nebula is about 10 light years in diameter and it is growing. Mathias Jäger of the European Space Agency explained the processes at work in an interview with The Guardian.
“The cloud gets denser and denser as you get to closer to its center, so at some point the cloud will be too dense for the weaker and weaker solar wind to push even further.”
Despite its great distance from earth, the Bubble Nebula was first discovered hundreds of years ago in 1787 by William Herschel, a British astronomer and pioneer of spectrophotometry. According to the Space Fellowship, the Bubble Nebula can be spotted inside the constellation Cassiopeia with a small telescope from earth.
The Bubble Nebula presents a number of issues that are interesting to Hubble Telescope scientists; among them is the fact that the star is not located at the center of the nearly spherical bubble of gas and dust.
The scale of the objects that the Hubble Telescope can view and then document in images is immense. A close-up view from the Hubble Telescope of the star inside the Bubble Nebula reveals several objects called cometary knots that surround it. Cometary knots look like comets with a small tail but are actually thought to be planetary nebulae or dying stars. As captured by the Hubble Telescope, they are small crescent-shaped formations with a tail lit up by the bright star SAO 20575. Each of these cometary knots are typically larger than our whole solar system.
The Hubble Telescope was the first of its kind and has been stunning the global public with a stream of mind-bending images since shortly after its launch on April 24, 1990.
[Image via NASA/ESA/Hubble Heritage Team]