As a way of commemorating 26 years since the launch of NASA’s Hubble Space Telescope (launched on April 24, 1990), astronomers have taken a stunning image of the Bubble Nebula, a massive bubble resembling a balloon blown into space by a large, hot star.
Every year, to mark the date, the Hubble Space Telescope observes a given object that has astronomical importance. NASA and ESA picked the Bubble Nebula this year. The Bubble Nebula was chosen to celebrate the occasion because it is incredible. The nebula reminds us of the fantastic scientific and photographic opportunities Hubble has opened up since it was launched 26 years ago, aboard the Shuttle Discovery.
During those years in space, Hubble has taken plenty of images beyond the solar system, which has helped astronomers to analyze and study the inner workings of the universe.
The Bubble Nebula (discovered by British astronomer and composer William Herschel in 1787), also referred to as NGC 7635, Sharpless 162 or Caldwell 1, lies in the constellation of Cassiopeia, 8000 light-years from Earth and is about 1.5 times the distance from the Sun to its nearest stellar neighbor. The bubble is ten light-years in diameter and was created by a bright, massive star that generated intense stellar wind.
The Wolf-Rayet star, which is the seething star forming the nebula, is between 10 and 20 times the mass of the sun. The Wolf-Rayet star, also referred to as SAO 20575, or BD +60 2522 is about four million years old and will likely detonate as a supernova in 10-20 million years. The star emits intense ultraviolet radiation, which has shaped the material from which it is formed over time into the nebula that is seen today. Gas on SAO 20575 gets incredibly hot and finds its way into space as a stellar wind.
Even though the bubble is symmetric, the star is not near the center of the bubble. Astronomers are uncertain how such a degree of symmetry has been maintained for such a long time.
Cometary knots also surround the star. Cometary knots are dense molecular clump that produce long tails when they encounter stellar winds. These cometary knots have masses comparable to that of Earth and are larger compared to the Solar System.
As the Bubble Nebula continues to expand, it has interacted with the giant molecular cloud around its territory. The cloud shines with light from SAO 2057. However, the bubble continues to grow facilitated by the stellar winds of over 60000 miles per hour.
Even though the nebula has been observed by Hubble before, this year has been different. Hubble’s Wide Field Camera 3 took four different photographs to form a mosaic. The combination was used to produce the highest-resolution view of the Nebula, probably explaining why the particular image was chosen to mark Hubble’s work for the last 26 years.
John Grunsfeld, astronaut and associate administrator of Science Mission Directorate at NASA Headquarters, in Washington, D.C, said, “As Hubble makes its 26th revolution around our home star, the Sun, we celebrate the event with a spectacular image of a dynamic and exciting interaction of a young star with its environment,”
“The view of the Bubble Nebula reminds us that Hubble gives us a front-row seat to the awe-inspiring Universe we live in,” He added.