Celestial Fireworks
Presented by Dr. Frank Summers, Space Telescope Science Institute

To help commemorate Hubble’s 25th anniversary in April 2015, our imaging team captured an amazing cluster of thousands of massive, hot, bright stars. The brilliance of the cluster inspired the metaphor of “celestial fireworks,” celebrating decades of astronomical accomplishments. To make this beautiful image even more eye-popping, our visualization team processed it into a three-dimensional computer model and created a flight into the nebula. In this episode, Dr. Summers explores the spectacular image and reveals behind-the-scenes details of how the visualization was made.

For more information: http://hubblesite.org/explore_astronomy/hubbles_universe_unfiltered

Hubble Press Release:
Hubble Space Telescope Celebrates 25 Years of Unveiling the Universe
http://hubblesite.org/newscenter/archive/releases/2015/12/

Show Notes:

— It is remarkable that the Hubble Space Telescope reached the 25 year milestone. However, that doesn’t mean the telescope is “old.” The five servicing missions to the telescope provided a continuing series of advances in both the observatory hardware and the scientific instruments. In addition, two decades of experience running the observatory have brought about vast improvements in efficiency and yield. In so many ways, Hubble has increased its capabilities over the years and gotten demonstrably better with age. Scientific productivity is perhaps the best measure of the vitality of a telescope, and on that measure Hubble is a robust as it has ever been.

— A search for the Spitzer Space Telescope image of the nebula Gum 29 finds an object known as RCW 49. They are the same nebula. There are multiple catalogs of nebulae by different astronomers, at different observatories, at different times. Colin Stanley Gum published his study of 84 nebulae in 1955, while the team of Rodgers, Campbell, and Whiteoak (RCW) produced a catalog of 182 objects in 1960. Other catalogs of nebulae include those of Caldwell and Sharpless. A nebula can be referenced by any of these catalog names, or by the more well-known NGC catalog number if such an entry exists. Unfortunately, there is no one standard naming convention, and cross-referencing between catalogs is a standard feature in astronomy.

— In many of our visualizations, the stars were handled as image cutouts. If there are just a few hundred stars in an image, the process of identifying the pixels associated with each star is not overly cumbersome. Software written for astronomical research addresses such tasks and can be applied to visualization. However, dense star clusters with many thousands of stars present a severe challenge with tremendous overlap amongst the stars. The point-spread function technique, described in the video, is also an adaptation of research software. Although developed specifically for star clusters, the process can be applied to any image.

— The development of computer graphics software to support Hollywood movies has greatly benefited our work in scientific visualizations. Astronomy is not a large enough market for specialized visualization software to be particularly profitable. Instead, we use the software written for the billion-dollar film market, and adapt it to our purposes. The sophisticated tools for look development, virtual cameras, and image rendering help add a cinematic feel, while we can keep track of the scientific details and ensure the presentation is astronomically appropriate. We strive for a combination of accuracy and aesthetics.

Image Notes:

Zoom to Gum 29 (movie)
Credit: NASA, ESA, G. Bacon, and Z. Levay (STScI)
Acknowledgment: A. Fujii, the Digitized Sky Survey 2 (STScI/AURA, Palomar/Caltech, and UKSTU/AAO), ESO, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team

Nebula Gum 29
Credit: ESO

Nebula Gum 29, infrared
Credit: NASA/JPL-Caltech/E. Churchwell (University of Wisconsin)

Star Cluster Westerlund 2, x-ray
Credit: NASA/CXC/Univ. de Liège/Y. Naze et al

Nebula Gum 29 and Star Cluster Westerlund 2
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team

Flight to Star Cluster Westerlund 2 (movie)
Credit: NASA, ESA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (Viz3D Team, STScI), and J. Anderson (STScI)
Acknowledgment: The Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), the Westerlund 2 Science Team, and ESO