New Hubble image pays tribute to WFPC2

The Hubble community bids farewell to the soon-to-be decommissioned Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope. In tribute to Hubble's longest running optical camera, a planetary nebula has been imaged as WFPC2's final "pretty picture".

This planetary nebula is known as Kohoutek 4-55 (or K 4-55). It is one of a series of planetary nebulae that were named after their discoverer, Czech astronomer Luboš Kohoutek. A planetary nebula is formed from material in the outer layers of a red giant star that were expelled into interstellar space when the star was in the late stages of its life. Ultraviolet radiation emitted from the remaining hot core of the star ionises the ejected gas shells, causing them to glow.

In the specific case of K 4-55, a bright inner ring is surrounded an asymmetric, fainter layer. The entire system is then surrounded by a faint red halo of light emitted by ionised nitrogen. This multi-shell structure is fairly uncommon in planetary nebulae.

This Hubble image was taken on 4 May 2009, with WFPC2. The colours represent the makeup of the various emission regions in the nebula: red represents nitrogen, green indicates hydrogen and blue, oxygen. K 4-55 is nearly 4600 light-years away in the constellation of Cygnus.

The WFPC2 instrument, which was installed in 1993 to replace the Wide Field/Planetary Camera, will be removed to make room for the Wide Field Camera 3 during the upcoming Hubble Servicing Mission.

During the camera's 16-year tour of duty, WFPC2 has provided outstanding science and spectacular images of the cosmos, an enduring legacy of astronomical treasures. Some of its best-remembered images are of the "Pillars of Creation" in the Eagle Nebula, Comet P/Shoemaker-Levy 9's impact on Jupiter's atmosphere and the 1995 Hubble Deep Field — the longest and deepest Hubble optical image of its time.

Kohoutek used ESO telescopes extensively at La Silla, Chile, to conduct much of his research on planetary nebulae. The Czech Republic became the thirteenth member state of the European Southern Observatory in 2007.

Image caption: see here
Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA). Acknowledgment: R. Sahai and J. Trauger (Jet Propulsion Laboratory)