Oldest Stars Found Near
Milky Way’s Centre
Astronomers have discovered the oldest stars ever seen, dating
from before the Milky Way formed when the universe was just
300 million years old.
The nine stars, found near the centre of the Milky Way, are
surprisingly pure but contain material from an even earlier star
that died in an enormous explosion called a hypernova.
“These pristine stars are among the oldest surviving stars in the
universe, and certainly the oldest stars we have ever seen,” said
Louise Howes of The Australian National University. “These
stars formed before the Milky Way, and the galaxy formed around
them,” said Howes, who was lead author of the study published in
Nature(tinyurl.com/pbcnqox).
The discovery and analysis of the nine pure stars challenges
current theories about the environment of the early universe from
which these stars formed.
“The stars have surprisingly low levels of carbon, iron and other
heavy elements, which suggests the first stars might not have
exploded as normal supernovae,” Howes said. “Perhaps they ended
their lives as hypernovae – poorly understood explosions of prob-
ably rapidly rotating stars producing ten times as much energy as
normal supernovae.”
ANU project leader Prof Martin Asplund said that finding
such rare relic stars among the billions of stars in the Milky Way’s
centre was like finding a needle in a haystack. “The ANU
SkyMapper telescope has a unique ability to detect the distinct
colours of anaemic stars – stars with little iron – which has been
vital for this search,” he said.
Following the team’s discovery in 2014 of an extremely old star
on the edge of the Milky Way, they focused on the dense central
parts of the galaxy, where stars formed even earlier. The team sifted
through about five million stars observed with SkyMapper to select
the most pure and therefore oldest specimens, which were then
studied in more detail using the Anglo-Australian Telescope and
the Magellan telescope in Chile.
The team also demonstrated that the stars spend their entire lives
near the Milky Way’s centre and are not just passing through it,
a further indication that the stars really are the oldest known stars
in the universe.JAN/FEB 2016|| 11Combinations of a significant number of non-toxic chemicals, many
of which can be found in plants and foods, may help treat advanced
and untreatable cancers, according to new research from a global
taskforce of 180 scientists.
Prof Lynn Ferguson of The University of Auckland, whose team
focused on genomic instability, says the research published in
Seminars in Cancer Biology (tinyurl.com/pdxkt2x) suggests that
non-toxic doses of plant and food chemicals may even address
cancer relapse.
“While current therapies have achieved modest successes in
some cancers, significant problems remain with most of our
approaches to treatment,” Ferguson says. “In particular, many newer
targeted therapies are extremely expensive, highly toxic and not
effective for rare types of cancer and advanced cancers.
“Even when they appear to work, a significant percentage of
patients will experience a relapse after only a few months,” she says.
“Typically advanced cancers are untreatable and relapses occur
when small sub-populations of mutated cells become resistant to
therapy. Doctors who try to address this problem with combinations
of therapies find that therapeutic toxicity typically limits their
ability to stop many cancers.”
To tackle this problem, the taskforce nominated 74 high-prioritymolecular targets that could be reached with chemicals to improve
patient outcomes. Corresponding low-toxicity chemical approaches
were then recommended as potential candidates for a mixture of
chemicals that could reach a broad-spectrum of priority targets in
most cancer types.
“While some chemicals, such as metformin and dichloroacetate,
are older drugs that have potential due to their low toxicity, many of
the chemicals that were selected, such as resveratrol in grapes,
genistein in soy, curcumin and others, can be extracted from plants
and foods,” says lead author Dr Keith Block of the Block Centre for
Integrative Cancer Treatment in Illinois.
“Although most have been studied for individual anti-cancer
effects, there has been almost no research done on substantial
combinations of these chemicals,” he says. “The taskforce teams
have emerged believing that carefully designed combinations of
non-toxic chemicals can be developed that will maximise our
chances of arresting most cancers.”
The taskforce also wanted to produce an approach to therapy
that would have the potential to be cheap because many of the
latest cancer therapies are deemed unaffordable in low-to-middle
income countries. Animal trials are now needed to advance this
approach before human trials are possible.Plant-based Chemicals Could Reverse Terminal Cancer
Artist’s impression of a hypernova, in which an explosion of
rapidly rotating stars produces ten times as much energy as
normal supernovae. Credit: ESO