Zoom 13 Million Light-years to See Heart of Active Galaxy

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Using data from the Very Large Telescope’s powerful near-infrared eyes, astronomers have created a movie that takes you across 13 million light-years to galaxy NGC 253, an active galaxy filled with young, massive and dusty stellar nurseries. “We now think that these are probably very active nurseries that contain many stars bursting from their dusty cocoons,” says Jose Antonio Acosta-Pulido, a member of the team from Instituto de Astrofísica de Canarias in Spain. NGC 253 is known as a starburst galaxy, after its very intense star formation activity. Each bright region could contain as many as one hundred thousand young, massive stars. And in the center of this galaxy appears a strikingly familiar sight: a virtual twin of our own Milky Way’s supermassive black hole.

Watch the movie. (For different viewing options, click here).

The astronomers used NACO, a sharp-eyed adaptive optics instrument on the VLT to study the fine detail in NGC 253, one of the brightest and dustiest spiral galaxies in the sky. Adaptive Optics (AO) corrects for the blurring effect introduced by the Earth’s atmosphere. This turbulence causes the stars to twinkle in a way that delights poets, but frustrates astronomers, since it smears out the images. With AO in action the telescope can produce images that are as sharp as is theoretically possible, as if the telescope were in space.

NACO revealed features in the galaxy that were only 11 light-years across. “Our observations provide us with so much spatially resolved detail that we can, for the first time, compare them with the finest radio maps for this galaxy — maps that have existed for more than a decade,” says Juan Antonio Fernández-Ontiveros, the lead author of the paper reporting the results.

Astronomers identified 37 distinct bright regions packed into a tiny region at the core of the galaxy, comprising just one percent of the galaxy’s total size. This is three times more than seen previously. The astronomers combined their NACO images with data from the infrared instrument on VLT, the VISIR, as well as with images from the NASA/ESA Hubble Space Telescope and radio observations made by the Very Large Array and the Very Large Baseline Interferometer. Combining these observations, taken in different wavelength regimes, provided a clue to the nature of these regions.

In looking at all the data together, astronomers concluded that the center of NGC 253 hosts a scaled-up version of Sagittarius A*, the bright radio source that lies at the core of the Milky Way and which we know harbors a massive black hole. “We have thus discovered what could be a twin of our Galaxy’s Centre,” says co-author Almudena Prieto.

Source: ESO