Press Release

A Holiday Gift from Space: Spitzer Photographs Christmas Tree Cluster

By SpaceRef Editor
December 22, 2005
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A Holiday Gift from Space: Spitzer Photographs Christmas Tree Cluster

Cambridge, MA – The signs of the holidays are all around us – wreaths on doors, twinkling lights in windows, and decorated trees in living rooms. Even outer space is joining the year-end celebration with this new image of a star-forming region called the Christmas Tree cluster recently taken by NASA’s Spitzer Space Telescope.

The Christmas Tree cluster was nicknamed by amateur astronomers for its appearance through small telescopes, which show a triangular outline of stars like a tree bedecked by dazzling holiday lights. The new infrared image reveals a different view: ribbons of gas and dust swirling like snow blowing in frigid winter winds and adorned by a festive collection of brilliant stars. The complex and breathtaking pattern of nebular emission traces a massive molecular cloud from which the cluster formed only recently.

Astronomers constructed the new image using data from two infrared cameras on Spitzer: the Infrared Array Camera, developed by the Smithsonian Astrophysical Observatory, and the Multiband Imaging Photometer for Spitzer, developed by the University of Arizona’s Steward Observatory. The dramatic appearance of the Christmas Tree cluster in infrared light results from heat radiation from ribbons of glowing dust that swaddle dozens of newborn stars just beginning to emerge from their natal cocoons.

“Hundreds of new stars and planetary systems have been produced over the past few million years in a prodigious burst of birthing activity within this enormous star-making factory,” said Charles Lada of the Harvard-Smithsonian Center for Astrophysics (CfA), a co-author on the study presenting the new image.

With Spitzer, astronomers can observe the nebula in otherwise invisible infrared light (or heat). Dust particles that permeate the cloud glow warmly in the infrared and reveal the intricate structure of the material that makes up this giant cloud. Moreover, infrared radiation provides astronomers with a much deeper view than visible radiation into the celestial womb of gas and dust that make up this massive molecular cloud. As a result they can directly observe growing young stellar embryos, known as protostars, which are otherwise invisible.

The Spitzer images reveal a conspicuous and curious new ornament on the “Christmas tree”: a collection of bright young protostars spatially arranged in a geometrical configuration that resembles spokes on a wheel or perhaps the pattern of a snowflake ornament. This new ornament is only now, for the first time, rendered visible by Spitzer’s unique infrared detectors.

“That was a wonderful holiday surprise for us!” said Paula Teixeira of CfA, lead author on the study. “The spatial regularity of these protostars provides us with a critical clue about the very nature of the process of stellar birth in the Spokes, or Snowflake, cluster.”

The spacings of the protostars in the Snowflake cluster confirm basic theoretical expectations, which predict that the average distance between forming protostars should be set by the density and temperature of the natal cloudy material.

The cluster is located about 3.000 light-years from the Earth in the constellation Monoceros the Unicorn.

Additional Spitzer images of the Christmas Tree cluster are online at

JPL manages the Spitzer mission for NASA’s Science Mission Directorate. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. NASA’s Goddard Space Flight Center built Spitzer’s Infrared Array Camera. The instrument’s principal investigator is Giovanni Fazio of CfA.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David Aguilar

Christine Pulliam

Whitney Clavin
Jet Propulsion Laboratory

Note to editors: High-resolution images to accompany this release are online at

SpaceRef staff editor.