Globular cluster M4. Credit: NOAO/AURA/NSF
Using recent advancements in Australian telescope tech, a Monash Uni team has made an unexpected discovery that a large group of stars are dying prematurely, challenging our accepted view of stellar evolution revealing that large numbers of helium burning stars are dying prematurely in the M4 globular cluster. M4 is one of the closest and brightest globular clusters, and has already been very well studied. “Globular clusters are some of the oldest objects in the Universe. Although we have some ideas for what is going on in them, every time we look carefully we find something unexpected” said Professor Lattanzio.
Researchers used a new instrument called a high efficiency and resolution multi-element spectrograph (HERMES). With HERMES fitted to the Anglo Australian Telescope (AAT) and operated by the AAO, the researchers uncovered the surprising results by working out the chemical composition of stars in M4 by deciphering their starlight. The international team found that about half of the stars tend to skip the Red Giant phase, instead becoming White Dwarfs millions of years ahead of schedule. While the cause of this remains a mystery, the HERMES chemical analysis has revealed that premature death tends to only occur in the sodium-rich/oxygen-poor stars. The surprising thing is that our best models of these stars do not predict that they will die young.
These findings build on previous Monash University-led research which made the initial discovery that many stars were dying prematurely in the globular cluster NGC 6752. Commenting on this discovery, Dr Simon Campbell said he was surprised to find these results extend to much more ‘normal’ stars’. “Although the phenomenon of sodium-rich stars failing to reach old age has been seen in our previous research, it was totally unexpected that it should occur on such a scale in this ‘normal’ star cluster, ” Dr Campbell said.
“HERMES represents a significant step forward for Australia’s observational capacity. This incredible advance is unique in that it combines multi-object capability with high data quality. Otherwise we are limited to observing one star at a time to collect such high quality data. This capability makes HERMES and the AAT competitive against some of the world’s biggest telescopes and a new tool for making breakthrough discoveries,” Dr De Silva said.Looking to the future research in this field, Professor Lattanzio highlighted the role that advanced computer simulations will play in the next stage of research.
“Computer simulations do not agree with this observation; so as well as continuing observations, new computer models will need to be generated to better understand what is taking place in the cores of these stars,” Professor Lattanzio said. http://www.monash.edu/news/show/stellar-mystery-deepens
Recent Comments