Right Ascension	1 : 34.5 (h:m)
Declination	+30 : 48 (deg:m)
Distance	3000 (kly)
Apparent Dimension	1 (arc min)

Discovered by William Herschel on September 11, 1784.

This is a Hubble Space Telescope image (right) of a vast nebula NGC 604 in the Triangulum galaxy M33.

This is a site where new stars are being born in a spiral arm of the galaxy. Though such nebulae are common in galaxies, this one is particularly large, nearly 1,500 light-years across. The nebula is so vast it is easily seen in ground-based telescopic images (left).

At the heart of NGC 604 are over 200 hot stars, much more massive than our Sun (15 to 60 solar masses). They heat the gaseous walls of the nebula making the gas fluoresce. Their light also highlights the nebula's three-dimensional shape, like a lantern in a cavern. By studying the physical structure of a giant nebula, astronomers may determine how clusters of massive stars affect the evolution of the interstellar medium of the galaxy. The nebula also yields clues to its star formation history and will improve understanding of the starburst process when a galaxy undergoes a "firestorm" of star formation.

The image was taken on January 17, 1995 with Hubble's Wide Field and Planetary Camera 2. Separate exposures were taken in different colors of light to study the physical properties of the hot gas (17,000 degrees Fahrenheit, 10,000 degrees Kelvin).

Credits: Hui Yang (University of Illinois), Jeff J. Hester (Arizona State University), and NASA.

This image is also available as ~810k color and ~740k b/w hi-res jpeg

Observing Reports for NGC 604 (IAAC Netastrocatalog)

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Hartmut Frommert
Christine Kronberg
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Last Modification: April 18, 1998