Today, NASA released the first official images taken by the newly upgraded Hubble Space Telescope. The new instrument installed on Hubble in May 2009, The Wide Field Camera 3 (WFC3), contains CCD image sensors made by e2v Technologies (Chelmsford, England).
The ultraviolet-visible (UVIS) channel of the WFC3 includes the company's CCD-43 imaging sensor, which has 4k x 2k pixels, each 15 microns in size with quantum efficiency of 50% at 250 nm and 65% at 500 nm. Two of the units are placed close together to create an image area with 4k x 4k pixels.
The WFC3 is able to take large-scale, extremely clear and detailed pictures of the universe over a very wide range of colors. It delivers more than a 10X improvement over the previous camera (WFPC2) in efficiency at UV wavelengths.
The Butterfly Nebula
Here, the revitalized Hubble has taken an image of the Butterfly Nebula (a planetary nebula catalogued as NGC 6302), which is about 3800 light-years away. What resemble butterfly wings are actually gas heated to more than 36,000 degrees Fahrenheit. The gas is moving at more than 600,000 miles an hour.
A dying star that was once about five times the mass of the Sun lies at the point where the two wings meet. It has ejected its envelope of gases and is now unleashing a stream of ultraviolet radiation that is making the cast-off material glow. The "butterfly" stretches for more than two light-years, which is about half the distance from the Sun to the nearest star, Alpha Centauri.
The central star itself cannot be seen, because it is hidden within a doughnut-shaped ring of dust, which appears as a dark band pinching the nebula in the center. The thick dust belt constricts the star's outflow, creating the classic hourglass shape displayed by some planetary nebulae.
The star's surface temperature is estimated to be about 400,000 degrees Fahrenheit, making it one of the hottest known stars in our galaxy. Spectroscopic observations made with ground-based telescopes show that the gas is roughly 36,000 degrees Fahrenheit, which is unusually hot compared to a typical planetary nebula.
The WFC3 image reveals a complex history of ejections from the star. The star first evolved into a huge red-giant star, with a diameter of about 1,000 times that of our Sun. It then lost its extended outer layers. Some of this gas was cast off from its equator at a relatively slow speed, perhaps as low as 20,000 miles an hour, creating the doughnut-shaped ring. Other gas was ejected perpendicular to the ring at higher speeds, producing the elongated wings of the butterfly-shaped structure. Later, as the central star heated up, a much faster stellar wind, a stream of charged particles traveling at more than 2 million miles an hour, plowed through the existing wing-shaped structure, further modifying its shape.
NGC 6302 was imaged on July 27, 2009 with Hubble's WFC3 in ultraviolet and visible light. Filters that isolate emissions from oxygen, helium, hydrogen, nitrogen, and sulfur from the planetary nebula were used.
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.