An annotated artist's impression showing radio waves travelling from the
new galaxies, then passing through the Milky Way and arriving at the
Parkes radio telescope on Earth (not to scale). Credit: ICRAR
An artist’s impression of the galaxies found in the ‘Zone of Avoidance’
behind the Milky Way. This scene has been created using the actual
positional data of the new galaxies and randomly populating the region
with galaxies of different sizes, types and colours. Credit: ICRAR
An animation showing the location of the galaxies discovered in the
'Zone of Avoidance'. Until now this region of space has remained hidden
from view because of the gas and dust of the Milky Way which blocks
light at optical wavelengths from reaching telescopes on Earth. By using
CSIRO's Parkes radio telescope to detect radio waves that can travel
through our galaxy's gas and dust, hundreds of new galaxies have been
found in the region of space known to astronomers as the 'Zone of
Avoidance'. This animation has been created using the actual positional
data of the new galaxies and randomly populating the region with
galaxies of different sizes, types and colours. Credit: ICRAR. Music by
Holly Broadbent.
An annotated animation showing the location of the galaxies discovered
in the 'Zone of Avoidance'. Until now this region of space has remained
hidden from view because of the gas and dust of the Milky Way which
blocks light at optical wavelengths from reaching telescopes on Earth.
By using CSIRO's Parkes radio telescope to detect radio waves that can
travel through our galaxy's gas and dust, hundreds of new galaxies have
been found in the region of space known to astronomers as the 'Zone of
Avoidance'. This animation has been created using the actual positional
data of the new galaxies and randomly populating the region with
galaxies of different sizes, types and colours. Credit: ICRAR. Music by
Holly Broadbent.
A visualisation showing the coordinates of the new 'hidden galaxies'. At
the centre is Earth. Blue represents galaxies found in other surveys
and other colours show the locations of the new galaxies. Credit: ICRAR
Hidden Galaxies Animation
Download link
Hundreds of hidden nearby galaxies have been studied for the first time, shedding light on a mysterious gravitational anomaly dubbed the Great Attractor.
Despite being just 250 million light years from Earth—very close in
astronomical terms—the new galaxies had been hidden from view until now
by our own galaxy, the Milky Way.
Using CSIRO’s Parkes radio telescope equipped with an innovative
receiver, an international team of scientists were able to see through
the stars and dust of the Milky Way, into a previously unexplored region
of space.
The discovery may help to explain the Great Attractor region, which
appears to be drawing the Milky Way and hundreds of thousands of other
galaxies towards it with a gravitational force equivalent to a million
billion Suns.
Lead author Professor Lister Staveley-Smith, from The University of
Western Australia node of the International Centre for Radio Astronomy
Research (ICRAR), said the team found 883 galaxies, a third of which had
never been seen before.
“The Milky Way is very beautiful of course and it’s very interesting to
study our own galaxy but it completely blocks out the view of the more
distant galaxies behind it,” he said.
Professor Staveley-Smith said scientists have been trying to get to the
bottom of the mysterious Great Attractor since major deviations from
universal expansion were first discovered in the 1970s and 1980s.
“We don’t actually understand what’s causing this gravitational
acceleration on the Milky Way or where it’s coming from,” he said.
“We know that in this region there are a few very large collections of
galaxies we call clusters or superclusters, and our whole Milky Way is
moving towards them at more than two million kilometres per hour.”
The research identified several new structures that could help to
explain the movement of the Milky Way, including three galaxy
concentrations (named NW1, NW2 and NW3) and two new clusters (named CW1
and CW2).
University of Cape Town astronomer Professor Renée Kraan-Korteweg said
astronomers have been trying to map the galaxy distribution hidden
behind the Milky Way for decades.
“We’ve used a range of techniques but only radio observations have
really succeeded in allowing us to see through the thickest foreground
layer of dust and stars,” she said.
“An average galaxy contains 100 billion stars, so finding hundreds of
new galaxies hidden behind the Milky Way points to a lot of mass we
didn't know about until now.”
Dr. Bärbel Koribalski from CSIRO Astronomy and Space Science said
innovative technologies on the Parkes Radio telescope had made it
possible to survey large areas of the sky very quickly.
“With the 21-cm multibeam receiver on Parkes we’re able to map the sky
13 times faster than we could before and make new discoveries at a much
greater rate,” she said.
The study involved researchers from Australia, South Africa, the US and
the Netherlands, and was published today in the Astronomical Journal.
More Information
The International Centre for Radio Astronomy Research (ICRAR) is a joint
venture between Curtin University and The University of Western
Australia with support and funding from the State Government of Western
Australia.
Professor Lister Staveley-Smith is ICRAR’s Director of Science at UWA
and the Deputy Director of the ARC Centre of Excellence for All-sky
Astrophysics (CAASTRO).
Dr Bärbel S. Koribalski is a CSIRO Science Leader, leading the HI
group at CSIRO Astronomy and Space Science. Dr Koribalski and Prof
Staveley-Smith are the principal investigators of WALLABY, the ASKAP HI
All-Sky Survey.
The ‘Great Attractor’ is a diffuse concentration of mass 250 million
light-years away, that’s pulling our galaxy, the Milky Way, and hundreds
of thousands of other galaxies towards it.
CSIRO’s Parkes telescope, or “the Dish”, is a 64-metre radio telescope
located in New South Wales, Australia. The telescope has been in
operation since 1961 and continues to be at the forefront of
astronomical discovery.
Original publication details:
‘The Parkes HI Zone of Avoidance Survey’, published in the Astronomical Journal February 9th, 2016. Available at this link.
Contacts:
Prof. Lister Staveley-SmithUniversity of Western Australia, ICRAR, CAASTRO
Ph: +61 425 212 592
E: Lister.Staveley-Smith@icrar.org
Ph: +61 425 212 592
E: Lister.Staveley-Smith@icrar.org
Prof. Renée C. Kraan-KortewegUniversity of Cape Town
M: +27 21 650 5830
E: kraan@ast.uct.ac.za
M: +27 21 650 5830
E: kraan@ast.uct.ac.za
Dr Bärbel Koribalski CSIRO Astronomy and Space Science
M: +61 450 624 954
E: Baerbel.Koribalski@csiro.au
M: +61 450 624 954
E: Baerbel.Koribalski@csiro.au
Pete WheelerMedia Contact, ICRAR
M: +61 423 982 018
E: Pete.Wheeler@icrar.org
M: +61 423 982 018
E: Pete.Wheeler@icrar.org
Source: International Centre for Radio Astronomy Research (ICRAR)