A
sharp-eyed instrument on the Very Large Telescope has given astronomers a peek
at the heart of a nearby galaxy, revealing a host of young, massive and dusty
stellar nurseries and a possible twin of our own Milky Way's supermassive black
hole.
The galaxy,
dubbed NGC 253, is one of the brightest and dustiest spiral galaxies in the
sky. It is also known as the Sculptor Galaxy, because it is located in the
Sculptor constellation.
The
Sculptor Galaxy is a starbust galaxy, so-called because of very intense star
formation there.
Astronomers
from the Instituto de Astrofísica de Canarias in Spain used NACO, an adaptive
optics instrument on the European Southern Observatory's Very
Large Telescope (located in Atacama desert in northern Chile), to study NGC 253 in finer detail in the near-infrared.
Adaptive optics
corrects for the blurring effect that Earth's atmosphere can have on images
taken by ground-based telescopes. Sensors and deformable mirrors correct
distortions of incoming light, producing images as clear as if the telescope
were in space.
With its adaptive
optics system, NACO revealed features of NGC 253 that were only 11
light-years across.
The NACO
observations were combined with data from another VLT instrument, VISIR, and
images from the Hubble Space Telescope and radio observations made by the Very
Large Array and the Very Large Baseline Interferometer. (Because of their
longer wavelengths, radio signals aren't affected by atmospheric turbulence.)
"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," said team member Juan Antonio
Fernández-Ontiveros.
With the
images, the astronomers identified 37 distinct bright regions — a threefold
increase on previous results — packed into a tiny region at the core of the
galaxy that makes up just 1 percent of the galaxy's total size.
"We
now think that these are probably very active nurseries that contain many stars
bursting from their dusty cocoons," said team member Jose Antonio
Acosta-Pulido.
The
combined data also led the astronomers to conclude 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 is
known to harbor a massive black hole.
"We
have thus discovered what could be a twin of our galaxy's center," said
team member Almudena Prieto.
The team's
findings are detailed in the January issue of the journal Monthly Notices of
the Royal Astronomical Society Letters.
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