New class of old star cluster discovered

Aug 01, 2013
New class of old star cluster discovered
An example of the new type of star cluster discovered (left), and an example of a previously known globular star cluster (right). The images were taken with the Hubble Space Telescope and their distances from Earth confirmed by the Keck 2 Telescope.

(Phys.org) —Star clusters with properties not seen before have been discovered by an international team of astrophysicists, led by Swinburne University of Technology's Professor Duncan Forbes.

Using data from the Hubble Space Telescope and the W M Keck Observatory's 10 metre telescope in Hawaii, the researchers found several star clusters with sizes and masses that were previously not known to exist.

"Old, compact star clusters, such as , are well known to amateur astronomers," Professor Forbes said.

"Although globular star clusters were first discovered in 1665, it has taken more than 340 years to fully appreciate all the different types of star clusters that are made in the Universe."

The researchers confirmed the existence of a number of different star clusters, overturning the idea that star clusters only come in certain types.

"We now know that star clusters have a rather continuous range of size and mass without any gaps in their properties," Professor Forbes said.

"Our discovery was made possible by using the Hubble Space Telescope to measure the sizes of the star clusters and long exposures on the DEIMOS instrument fitted to the Keck II telescope to obtain distances and confirm their status." Professor Jean Brodie, a team member from the University of California, said.

They also measured the colour of the star clusters, finding the lower mass ones to be red and the higher mass ones to be blue in colour, suggesting differences in their .

"No single model for the formation of these star clusters can currently reproduce the diversity of structural properties we have observed for old star clusters," Professor Forbes said.

"Our observations present a challenge to researchers aiming to reproduce in ."

The research team included Vincenzo Pota and Christopher Usher (Swinburne University of Technology), Jay Strader (Michigan State University), Aaron Romanowsky (San Jose State University), Jean Brodie and Jacob Arnold (University of California), and Lee Spitler (Macquarie University).

The paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society, published by Oxford University Press.

The Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS) is capable of gathering spectra from 130 galaxies or more in a single exposure. In "Mega Mask" mode, DEIMOS can take spectra of more than 1,200 objects at once, using a special narrow-band filter.

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User comments : 4

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Tuxford
1 / 5 (6) Aug 01, 2013
Galactic clusters no longer able to be distinctly classified. Heaven forfend! Another crisis for the irrationally rationale mind. Nature displaying an unacceptably wide range of cluster formation. Shocking.

Not shocking if one can grasp that likely most clusters grow from the inside out, from the core star ejections, who was likely ejected from a still larger galactic core star, thereby forming the basis for the growth of a cluster eventually into a satellite galaxy. But this will drive the rationale mind over the irrational cliff. No. Back to Disneyland.
Fleetfoot
5 / 5 (5) Aug 02, 2013
Galactic clusters no longer able to be distinctly classified. Heaven forfend! Another crisis for the irrationally rationale mind. Nature displaying an unacceptably wide range of cluster formation. Shocking.


No, just another crank displaying an inability to read simple English. From the paper:

"Utilizing the Hubble Space Telescope (HST) to measure sizes, and long exposures on the Keck 10m telescope to obtain distances, we have discovered the first confirmed star clusters that lie within a previously claimed size-luminosity gap dubbed the `avoidance zone' by Hwang et al (2011)."

The range is no larger than before, these observations lie within the a section in the middle suggesting it is a dip rather than a "gap", or perhaps the edges of the populations overlap rather than being slightly separated.

Not shocking if one can grasp that likely most clusters grow from the inside out. ... Back to Disneyland.


It's the best place for clueless nonsense like that.
Tuxford
1 / 5 (5) Aug 02, 2013
"No single model for the formation of these star clusters can currently reproduce the diversity of structural properties we have observed for old star clusters," Professor Forbes said.

Fleet. I find your reaction within the realm of intellectual egomania. A little introspection may be called for. Other egomaniacs are bound not the rock the intellectual boat too much with outlandish conclusions, lest they be tossed overboard and suffer career ending ridicule.

Fleet. Let me help. "You are so smart." Feel better now?
Fleetfoot
5 / 5 (2) Aug 02, 2013
"No single model for the formation of these star clusters can currently reproduce the diversity of structural properties we have observed for old star clusters," Professor Forbes said.

Fleet. I find your reaction within the realm of intellectual egomania. A little introspection may be called for. Other egomaniacs are bound not the rock the intellectual boat too much with outlandish conclusions, lest they be tossed overboard and suffer career ending ridicule.

Fleet. Let me help. "You are so smart." Feel better now?


There's an old saying you should learn, "when you're in a hole, stop digging." Try reading the paper and seeing where the new objects lie in relation to the general groups before making yourself look even sillier.