Astronomers spun up by galaxy-shape finding

September 11, 2017, University of Sydney
Galaxies from the SAMI survey, imaged with Japan's Subaru telescope. Credit: D. Taranu (University of Western Australia), C. Foster (University of Sydney), NAOJ (the National Astronomical Observatory of Japan)

For the first time astronomers have measured how a galaxy's spin affects its shape.

It sounds simple, but measuring a galaxy's true 3D shape is a tricky problem that astronomers first tried to solve 90 years ago.

"This is the first time we've been able to reliably measure how a galaxy's shape depends on any of its other properties - in this case, its rotation speed," said research team leader Dr Caroline Foster of the University of Sydney, who completed this research while working at the Australian Astronomical Observatory.

The study is published today in the journal Monthly Notices of the Royal Astronomical Society.

Galaxies can be shaped like a pancake, a sea urchin or a football, or anything in between.

Faster-spinning are flatter than their slower-spinning siblings, the team found.

"And among spiral galaxies, which have disks of stars, the faster-spinning ones have more circular disks," said team member Professor Scott Croom of the University of Sydney.

The team made its findings with SAMI (the Sydney-AAO Multi-object Integral field unit), an instrument jointly developed by The University of Sydney and the Australian Astronomical Observatory with funding from CAASTRO, the ARC Centre of Excellence for All-sky Astrophysics.

The SAMI instrument at the 3.9m Anglo-Australian Telescope. Each silver cable holds a 'hexabundle' of special optical fibres that can look at several different points across the face of a single galaxy. SAMI can study 13 galaxies at a time. The orange cables also hold optical fibres: these are used for calibration purposes. Credit: Ángel R. López-Sánchez.

SAMI gives detailed information about the movement of gas and stars inside galaxies. It can examine 13 galaxies at a time and so collect data on huge numbers of them.

Dr Foster's team used a sample of 845 galaxies, over three times more than the biggest previous study. This large number was the key to solving the shape problem.

Because a galaxy's shape is the result of past events such as merging with other galaxies, knowing its shape also tells us about the galaxy's history.

Explore further: Scientists unveil new 3-D view of galaxies

More information: Monthly Notices of the Royal Astronomical Society (2017). doi.org/10.1093/mnras/stx1869

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wduckss
1 / 5 (2) Sep 11, 2017
Nothing new.
"From the astronomic observations the rotation can be divided into these categories: slow cyclones (they exist on the poles of Sun and similar stars of the slow rotation, as well as on some gas giants); fast cyclones (the shiny stars with a high speed rotation; also, the centers of spiral galaxies); very fast cyclones (elliptical galaxies and so-called pulsars or neutron stars). The faster the rotation, the stronger the gravitational forces a ara. .."
2013/14
http://www.svemir...html#14b etc.
rrwillsj
1 / 5 (2) Sep 18, 2017
wds, uhh, what the heck does rotation have to do with field power of gravity? The gravitational force is a constant of mass.

It don't matter whether you are doing a quick pirouette en point across the floor or a graceful grand pas de chat across a stage. Your body's 60 Kgs of mass is always 60Kgs of mass.

Even in a zero-g environment, a megagram of metal (with or without delta/v) produces a metagram of gravitational attraction. No matter what the rest of the universe is doing!

What I see as your greatest error is confusing force and energy. The few, small similarities (when visualized from the limits of a human perspective) between the force of gravity and the energy of electro-magnetism, are two fundamentally different events of this universe.

That is why no one has yet developed a GUT reconciling G and E/M. And I do not believe that such an all-encompassing theory is possible for explaining the realities of this universe.

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