At a cosmologically crisp 1 degree Kelvin (minus 272 degrees Celsius), the Boomerang nebula is the coldest known object in the universe — colder than the faint afterglow of the Big Bang, the explosive event that created the cosmos.
Astronomers using the Atacama Large Millimeter/sub-millimeter Array (ALMA) telescope in Chile have taken a new look at this object to learn more about its frigid properties and to determine its true shape, which has an eerily ghost-like appearance.
“This ultra-cold object is extremely intriguing and we’re learning much more about its true nature with ALMA,” said Raghvendra Sahai, a researcher and principal scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and lead author of a paper published in Astrophysical Journal. “What seemed like a double lobe, or boomerang shape, from Earth-based optical telescopes, is actually a much broader structure that is expanding rapidly into space.”
The nebula revealed its true shape to ALMA in the image above. The background blue structure, as seen in visible light by NASA’s Hubble Space Telescope, shows a classic double-lobe shape with a narrow central region. ALMA’s resolution and ability to see cold gas molecules reveals the nebula’s more elongated shape, as seen in red.
Additional authors on the paper include Wouter Vlemmings, Chalmers University of Technology, Onsala, Sweden; Patrick Huggins, New York University, New York; Lars-Ake Nyman, Joint ALMA Observatory, Santiago de Chile; and Yiannis Gonidakis, CSIRO, Australia Telescope National Facility.
ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by the European Southern Observatory, on behalf of North America by the National Radio Astronomy Observatory, and on behalf of East Asia by the National Astronomical Observatory of Japan.