Subscribe free to our newsletters via your
. 24/7 Space News .




SKY NIGHTLY
Surprising Theorists, Stars Within Middle-Aged Clusters Are of Similar Age
by Staff Writers
Oxnard CA (SPX) Dec 18, 2014


NGC 1615, a middle-age star cluster located in the Large Magellanic Cloud, contains stars that are of a more uniform age than previously believed. Image courtesy NASA/ESA Hubble Space Telescope/Fabian RRRR. For a larger version of this image please go here.

A close look at the night sky reveals that stars don't like to be alone; instead, they congregate in clusters, in some cases containing as many as several million stars. Until recently, the oldest of these populous star clusters were considered well understood, with the stars in a single group having formed at different times, over periods of more than 300 million years.

Yet new research published online in the journal Nature suggests that the star formation in these clusters is more complex.

Using data from the Hubble Space Telescope, a team of researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University and the Chinese Academy of Science's National Astronomical Observatories in Beijing have found that, in large middle-aged clusters at least, all stars appear to be of about the same age.

Stars begin their lives as billowing clouds of dust and gas. Pulled together by gravity, these clouds slowly coalesce into dense spheres that, if they grow large enough, heat up and begin to convert hydrogen into helium in their cores.

This process releases energy and makes them shine. Billions of years later, when they reach the end of their core hydrogen supply, the stars begin to burn hydrogen in a shell around their cores and, as a result, their temperature changes.

Previous observations of massive star clusters revealed a relatively large amount of variation in temperature from stars reaching the end of their core hydrogen supply, suggesting that the stars within the clusters varied in age by as much as 300 million years or more.

"This has long been surprising," said Chengyuan Li, a doctoral student at Peking University and the lead author of the new study.

"Young clusters are thought to quickly lose any remaining star-forming gas during the first 10 million years of their lifetimes," which would make it difficult for the stars in a single cluster to vary in age by more than about 10 million years.

Observing a middle-aged, 2 billion-year-old star cluster located in the Large Magellanic Cloud called NGC 1651, the researchers looked for both the change in temperature that occurs when stars reach the end of their hydrogen supply - which is what previous studies had focused on - and a second change in temperature that occurs as the stars burn hydrogen in a shell around their core.

While they found the expected wide variation in temperature of stars finishing their core hydrogen reserves, the astronomers were surprised to find very little variation when looking at the brightnesses of stars of similar temperatures burning hydrogen in the shell outside the core.

The lack of variation among these stars led the researchers to conclude that the stars in this cluster must all be within just 80 million years of the same age - a very small age range for such an old cluster.

"NGC 1651 is the best example found to date of a truly single-age stellar population," said Richard de Grijs, a faculty member at KIAA involved in the study. "We have since identified a handful of other middle-aged clusters that appear to show similar features."

The research suggests that, for middle-aged clusters at least, today's conventional wisdom may be wrong and it might be common for all stars in a single cluster to be of approximately the same age.

A decade ago, astronomers actually thought that the stars within any cluster should all be about the same age, but that idea fell out of favor when clear evidence of the presence of stars of different ages within a single cluster was discovered, at least for the oldest and most populous clusters in our Milky Way. Based on today's Nature paper, a reverse shift looks necessary.

In addition to that important realization, the paper's authors suggest that the wide range of brightness seen in stars reaching the end of their core hydrogen supply may actually be due to stellar rotation. That's because two stars of exactly the same age can exhibit different levels of observed temperature if they rotate at significantly different rates.

Most current models don't take stellar rotation into account, de Grijs said. Future studies may offer even greater insight into the age of star clusters by better modeling stellar rotation rates and using those models to interpreting the variation in temperature of stars burning the last of their core hydrogen, he said.

Licai Deng, principal scientist at the National Astronomical Observatories, said, "these latest results resolve nearly a decade of debate among scientists; as such, the results were deemed 'solid and welcome' by the peer-reviewers."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Kavli Foundation
Astronomy News from Skynightly.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





SKY NIGHTLY
Galactic Gathering Gives Sparkling Light Display
Boston MA (SPX) Dec 15, 2014
At this time of year, holiday parties often include festive lights. When galaxies get together, they also may be surrounded by a spectacular light show. That's the case with NGC 2207 and IC 2163, which are located about 130 million light-years from Earth, in the constellation of Canis Major. This pair of spiral galaxies has been caught in a grazing encounter. NGC 2207 and IC 2163 have host ... read more


SKY NIGHTLY
Moon Express testing compact lunar lander at Kennedy

UK Plans to Drill Into Moon, Explore Feasibility of Manned Base

Carnegie Mellon Unveils Lunar Rover "Andy"

Why we should mine the moon

SKY NIGHTLY
Spike seen in methane on Mars, but source unknown

Mars Mountain was All Wet

Goddard instrument makes first detection of organic matter on Mars

MAVEN Identifies Links in Chain Leading to Mars Atmospheric Loss

SKY NIGHTLY
NASA Voyager: 'Tsunami Wave' Still Flies Through Interstellar Space

Russia, US to Cooperate on Orion Spacecraft Modernization

France's Accor in strategic alliance with China's Huazhu

From Myth to Legend: Orion Test a Success

SKY NIGHTLY
China's Long March puts satellite in orbit on 200th launch

Countdown to China's new space programs begins

China develops new rocket for manned moon mission: media

Service module of China's returned lunar orbiter reaches L2 point

SKY NIGHTLY
Boeing Covers Groundwork in Second Milestone For Commercial Crew

Orbital says it will complete ISS deliveries by end of 2016

OPALS: Light Beams Let Data Rates Soar

ATV views Space Station as never before

SKY NIGHTLY
2015 to be a busy year, says ISRO chief

ILS Proton launches Yamal-401 satellite marking 400th Proton mission

Russia launches Yamal-401 communication satellite

O3b satellites integrated on Soyuz For Dec 18 Arianespace flight

SKY NIGHTLY
Super-Earth spotted by ground-based telescope, a first

Astronomers spot Pluto-size objects swarming about young sun

Observing Solar System Worlds as if They Were Distant Exoplanets

Finding infant earths and potential life just got easier

SKY NIGHTLY
GaN-based LEDs in harsh radiation environments

New high-entropy alloy light as aluminum, as strong as titanium

Squid supplies blueprint for printable thermoplastics

Composite materials can be designed in a supercomputer virtual lab




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.