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




STELLAR CHEMISTRY
How to weigh the Milky Way
by Staff Writers
New York NY (SPX) Jun 04, 2015


File image.

What if your doctor told you that your weight is somewhere between 100 and 400 lbs.? With any ordinary scale every patient can do better at home. Yet, one patient can't: the Milky Way. Even though today we peer deeper into space than ever before, our home galaxy's weight is still unknown to about a factor of four. Researchers at Columbia University's Astronomy Department have now developed a new method to give the Milky Way a more precise physical checkup.

The Milky Way consists of roughly 100 billion stars that form a huge stellar disk with a diameter of 100-200 thousand light years. The Sun is part of this structure, hence, when we look into the sky, we look right into a gigantic disk of stars. The vast number of stars and the huge extent on the sky make it hard to measure fundamental quantities for the Milky Way, such as its weight.

An international team of scientists led by Columbia University researcher Andreas Kupper used stars outside this disk, which orbit around the Milky Way in a stream-like structure, to weigh the Milky Way to high precision.

In a new study published in The Astrophysical Journal, the team demonstrates that such streams, produced by dissolving globular clusters, can be used to measure not only the weight of our Galaxy, but can also be exploited as yardsticks to determine the location of the Sun within the Milky Way.

"Globular clusters are compact groups of thousands to several millions of stars that were born together when the universe was still very young," said Kupper.

"They orbit around the Milky Way and slowly disintegrate over the course of billions of years, leaving a unique trace behind. Such star streams stick out from the rest of the stars in the sky as they are dense and coherent, much like contrails from airplanes easily stick out from regular clouds."

The researchers used data from the Sloan Digital Sky Survey, which scanned the sky of the Northern Hemisphere for about 10 years to create a comprehensive catalog of stars in the sky.

The stream they tested the new technique on was produced by a globular cluster named Palomar 5, and had already been discovered in 2001 high above the Galactic disk. Eduardo Balbinot, coauthor on the current study from the University of Surrey in England, revisited the Sloan data and detected density wiggles in the stream of Palomar 5.

"We found the wiggles to be very pronounced and regularly spaced along the stream," said Balbinot. "Such variations cannot be random."

It is these wiggles that allow the researchers to gain the unprecedented precision of their measurement. Using the Yeti supercomputer of Columbia University, they created several million models of the stream in different realizations of the Milky Way.

From these models and from comparing the wiggle pattern of the models to the observations, they were able to infer the mass of the Milky Way within a radius of 60,000 light years to be 210 billion times the mass of the Sun with an uncertainty of only 20 percent. The unique pattern of the density wiggles helped significantly to rule out models of the Milky Way, which were either too heavy or too skinny.

"An important advance in this work was using robust statistical tools - the same ones used to study changes in the genome and employed by internet search engines to rank websites," explained Ana Bonaca, a coauthor from Yale University. This rigorous approach helped in achieving the high precision in weighing the Milky Way."

"Such measurements have been tried before with different streams, but the results were always quite ambiguous," added Professor Kathryn Johnston, coauthor of the study and chair of the Columbia Astronomy Department. "Our new measurement breaks these ambiguities by exploiting the unique density pattern that Palomar 5 created as it orbited around the Milky Way for the past 11 billion years."

In the future, the researchers aim to use more structures like the Palomar 5 stream to gain an even higher precision and to create the most realistic model of the Milky Way to date. From the improved precision the scientists hope to learn about the formation and composition of our home galaxy, and to understand how the Milky Way compares with other galaxies in the Universe. So far, the results indicate that the Milky Way is a healthy patient - neither too skinny nor too heavy for its size.

Lead author of the study "Globular Cluster Streams as Galactic High-Precision Scales - the Poster Child Palomar 5", Andreas Kupper, is a Hubble Fellow at the Astronomy Department of Columbia University. The Hubble Fellowship grants are awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA.


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
Columbia University
Stellar Chemistry, The Universe And All Within It






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





STELLAR CHEMISTRY
Charting the Milky Way From the Inside Out
Pasadena CA (JPL) Jun 04, 2015
Imagine trying to create a map of your house while confined to only the living room. You might peek through the doors into other rooms or look for light spilling in through the windows. But, in the end, the walls and lack of visibility would largely prevent you from seeing the big picture. The job of mapping our own Milky Way galaxy from planet Earth, situated about two-thirds of the way o ... read more


STELLAR CHEMISTRY
Crashing comets may explain mysterious lunar swirls

Google Lunar X-Prize meets Yoda

China, Russia plan joint landing on the Moon

NASA's LRO Moves Closer to the Lunar Surface

STELLAR CHEMISTRY
United Arab Emirates Hopes to Reach Mars by2021

NASA Begins Testing Next Mars Lander Insight

The Supreme Council of Parachute Experts

Science Drives NASA's Journey to Mars

STELLAR CHEMISTRY
LightSail reestablishes communication with mission control

NASA pushes flying saucer parachute test to Thursday

NASA's Exploration Plans Include Living Off the Land

Keeping astronauts in space longer with better air and water

STELLAR CHEMISTRY
China Plans First Ever Landing On The Lunar Far Side

China ranked 4th among world space powers

3D printer making Chinese space suit parts

Xinhua Insight: How China joins space club?

STELLAR CHEMISTRY
NASA Delays Approval on International Space Station Projects

Space Station remodelling

Space age mice are thin-skinned

NASA Begins Major Reconfiguration of International Space Station

STELLAR CHEMISTRY
Recent Proton loss to push up launch costs warns manufacturer

Air Force Certifies SpaceX for National Security Space Missions

SpaceX cleared for US military launches

Ariane 5's second launch of 2015

STELLAR CHEMISTRY
Astronomers Discover a Young Solar System Around a Nearby Star

Circular orbits identified for small exoplanets

Weather forecasts for planets beyond our solar system

Astrophysicists offer proof that famous image shows forming planets

STELLAR CHEMISTRY
MUOS-3 communications satellite completes in-orbit testing

Patent for Navy small space debris tracker granted

3D printers get Ugandan amputees back on their feet

Saving money and the environment with 3-D printing




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.