School teacher spots green blob

Mystery object appears to be a starless dwarf galaxy

Within a few weeks, astronomers are expected to formally report the discovery of an intensely hot, green ring of gas. They’ll make a Dutch primary school teacher an honorary coauthor to credit her for first drawing their attention to this apparently starless dwarf galaxy. It’s unlike any celestial object known.

MYSTERY BLOB After seeing an uncorrected version of this image, a school teacher alerted astronomers. Galaxy Zoo Team, Isaac Newton Telescope

Neighboring a massive spiral galaxy known as IC 2497, the newfound object radiates with an intensity and temperature higher than could be accounted for by ordinary starlight, observes astronomer
William Keel of the University of Alabama in Tuscaloosa.

He reports that analyses of the object’s emissions, earlier this year, suggest that it is being “lit by the ultraviolet light and X-rays from a quasar that has vanished in the last 100,000 years.” The quasar’s telltale ghostly radiance, or light echo, indicates the blob is very warmprobably 16,000° to 20,000° Celsius.

Quasar-light echoes have been witnessed ricocheting within small clouds, notes Chris Lintott of the University of Oxford in England. But none has ever illuminated a galaxy-sized object, as is being done here. That is among the features making this new object “weird,” Lintott sayseven “unique.”

Last July, he and other astronomers at several universities invited the public to visit a website named Galaxy Zoo and help catalog never-before-seen distant galaxies. The false-color images had been collected as part of the Sloan Digital Sky Survey.

Within a month, Hanny van Arkel, of Heerlen, the Netherlands, signed on. A few days later, she recalls, a strange deep-blue object in one photo made her do a double take. She reported the mystery blobwhich, in true color, is deep greenand it soon became affectionately known as Hanny’s Voorwerp (Dutch for “object”).

Hanny’s Voorwerp has proven so strange that astronomers have since been feverishly requesting observing time on telescopes around the world to learn more about it. Indeed, word arrived on May 30van Arkel’s 25th birthdaythat the Hubble Space Telescope would train its eye on this prize for seven orbits next year.

In its first year, the Galaxy Zoo project turned up plenty of other weird objects as well, Lintott reports, such as “this wonderful object called a ‘blue banana.’” He is clueless about what it might be, but he says that “at some point I’ve got to spend a few days trying to find out.”

Crows Lintott: “This is what I used to think astronomers did. We found something weird, looked at it with everything we could get our hands on and then worked out what it is.”

Janet Raloff

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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