Hubble Heritage Archive: NGC 3132

The text and images in this article were originally published on November 5, 1998, and reflect information about NGC 3132 available at that time.

A GLOWING POOL OF LIGHT

NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known to amateur astronomers in the southern hemisphere as the “Eight-Burst” or the “Southern Ring” Nebula. 

The name “planetary nebula” refers only to the round shape that many of these objects show when examined through a small visual telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes. NGC 3132 is nearly half a light-year in diameter, and at a distance of about 2000 light-years is one of the nearer known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second. 

This image, captured by NASA’s Hubble Space Telescope, clearly shows two stars near the center of the nebula, a bright white one, and an adjacent, fainter companion to its upper right. (A third, unrelated star lies near the edge of the nebula.) The faint partner is actually the star that has ejected the nebula. This star is now smaller than our own Sun, but extremely hot. The flood of ultraviolet radiation from its surface makes the surrounding gases glow through fluorescence. The brighter star is in an earlier stage of stellar evolution, but in the future it will probably eject its own planetary nebula. 

In the Heritage Team’s rendition of the Hubble image, the colors were chosen to represent the temperature of the gases. Blue represents the hottest gas, which is confined to the inner region of the nebula. Red represents the coolest gas, at the outer edge. The Hubble image also reveals a host of filaments, including one long one that resembles a waistband, made out of dust particles which have condensed out of the expanding gases. The dust particles are rich in elements such as carbon. Eons from now, these particles may be incorporated into new stars and planets when they form from interstellar gas and dust. Our own Sun may eject a similar planetary nebula some 6 billion years from now. 

Featured Image Credit: NASA and the Hubble Heritage Team (STScI/AURA) 
Acknowledgment: R. Sahai (Jet Propulsion Lab)

Fast Facts about NGC 3132

About this Object

About the Data

About this Image

Imaging Through Filters

The Hubble Heritage image of NGC 3132 was constructed from black-and-white Hubble Space Telescope data obtained from the public archive. The original observers used 5 different filters to select wavelengths of light corresponding to 5 different chemical elements which are each sensitive to different physical conditions within the nebula. Hence the 5 grayscale images displayed below appear somewhat different from each other. The Heritage Team assigned the primary colors of light to 3 of these images in order to construct the glowing image highlighted as our November 1998 release. In this case, color corresponds to excitation energy, which depends on the temperature of the gas and the amount of ultraviolet light from the hot star in the center. 

Nature displays a remarkable economy of form as displayed on the right by the striking similarity of Yellowstone’s Grand Prismatic Spring to the Hubble Heritage project’s new rendering of NGC 3132. Though the two physical systems are completely different, the reasons for the similarity of the images do share some common threads. In the Grand Prismatic Spring, the colors are produced by different species of thermophilic bacteria that live in narrow temperature ranges, as the waters of the hot spring naturally cool farther from the source of the heated water. The reddish bacteria at the outer edge survive in the coolest water, with the yellowish and greenish bacteria living in progressively hotter water. The water in the central blue area of the spring is too hot to support any of the bacterial species. 

The colors on the Heritage image of NGC 3132 are similarly derived with different colors tracing three different atomic species in the planetary nebula. The reddish colors show areas where singly ionized nitrogen emits; green maps out areas where the H-alpha emission from hydrogen occurs (yellow regions have both [N II] and H-alpha), and blue traces emission from doubly ionized oxygen, [O III]. The segregation of these species occurs because each atomic species requires different levels of ionizing radiation which decreases with distance from the central star. 

Image of Yellowstone Grand Prismatic Spring copyright Bonnie Sue Photography