Space

November 15, 2013

Hubble reveals first pictures of Milky Way’s formative years

nasa-hubble
NASA’s Hubble Space Telescope has revealed the first visual evidence of how our home galaxy, the Milky Way, assembled itself into the majestic pinwheel of stars we see today.

Astronomers used Hubble’s deep-sky surveys to study the evolution of 400 galaxies similar to the Milky Way and noted their appearance at various stages of development over a time span of 11 billion years. Judging from images of these far-flung galaxies, they found the Milky Way likely began as faint, blue, low-mass object containing lots of gas. Gas is the fuel for star birth and the blue color is an indicator of rapid star formation.

They also found the Milky Way probably was a flat disk with a bulge in the middle, both of which grew simultaneously into the majestic spiral seen today. The sun and Earth reside in the disk and the bulge is both full of older stars and home to a supermassive black hole that probably grew along with the galaxy.

“For the first time, we have direct images of what the Milky Way looked like in the past,” said study co-leader Pieter G. van Dokkum of Yale University in New Haven, Conn. “Of course, we can’t see the Milky Way itself in the past. We selected galaxies billions of light-years away that will evolve into galaxies like the Milky Way. By tracing the Milky Way’s siblings, we find that our galaxy built up 90 percent of its stars between 11 billion and 7 billion years ago, which is something that has not been measured directly before.”

The Hubble telescope’s superior resolving power, with which it can see extremely fine details, allowed the researchers to study how the structure of the Milky Way changed over time. At the peak of star formation, when the universe was about 4 billion years old, the Milky Way-like galaxies were pumping out about 15 stars a year. By comparison, the Milky Way today is creating only one star a year.

“You can see that these galaxies are fluffy and spread out,” said study co-leader Shannon Patel of Leiden University in The Netherlands. “There is no evidence of a bulge without a disk, around which the disk formed later.” Team member Erica Nelson, of Yale University, added: “These galaxies show us the whole Milky Way grew at the same time, unlike more massive elliptical galaxies, in which the central bulge forms first.”

To identify the far-flung galaxies and study them in detail, the research team used three of the largest Hubble programs, the 3D-HST survey, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and the Great Observatories Origins Deep Survey. These surveys combined spectroscopy with visible and near-infrared imaging by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys.

The research team’s analysis involved measuring the distances and sizes of the galaxies. The astronomers calculated the mass of each galaxy from its brightness and colors. They selected the galaxies in their census from a catalog they compiled of more than 100,000 galaxies. The survey galaxies are consistent with computer models, which show at early stages, a majority of the bulges of spiral galaxies were built up at the same time as their corresponding disks.

“In these observations, we’re capturing most of the evolution of the Milky Way,” explained team member Joel Leja of Yale University. “These deep surveys allow us to see the smaller galaxies. In previous observations we could only see the most luminous galaxies in the distant past, and now we can look at more normal galaxies. Hubble gives us the shapes and colors of these spirals as well as their distances from Earth. We also can measure the rates at which each part of the galaxies grew. All of this is difficult to do from the ground.”

The team’s results were published July 10 in The Astrophysical Journal Letters. A second paper appears in the Nov. 11 online edition of The Astrophysical Journal.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines November 24, 2014

News: Hagel said to be stepping down as defense chief under pressure - Defense Secretary Chuck Hagel is stepping down under pressure, the first cabinet-level casualty of President Obama’s Democratic majority in the Senate and a beleaguered national security team that has struggled to stay ahead of an onslaught of global crises. Afghan mission for U.S....
 
 

News Briefs November 24, 2014

Fog forces five U.S. choppers to land in Polish field Officials say that that fog forced five U.S. Army helicopters to make an emergency landing in a Polish field and spend the night there, the second such incident since September. The U.S. Army said 15 soldiers were moving equipment to their base in Germany Nov....
 
 
Air Force photograph by Samuel King Jr.

Navy’s first F-35C squadron surpasses 1,000 flight hours

Air Force photograph by Samuel King Jr. An F-35C Lightning II aircraft piloted by Lt. Cmdr. Chris Tabert, assigned to Strike Fighter Squadron (VFA) 101, flies the squadron’s first local sortie. The F-35C is the carrier va...
 

 
boeing-SC-787

Boeing South Carolina begins final assembly of its first 787-9 Dreamliner

Boeing has started final assembly of the 787-9 Dreamliner at its South Carolina facility. The team began joining large fuselage sections of the newest 787 Nov. 22 on schedule, a proud milestone for the South Carolina team and a...
 
 
Lockheed Martin image

Ball Aerospace equips Orion mission with key avionics, antenna hardware

Lockheed Martin image Ball Aerospace & Technologies Corp. is providing the phased array antennas and flight test cameras to prime contractor Lockheed Martin for Orion’s Exploration Flight Test-1 (EFT-1), which is an u...
 
 

Salina, Kansas, recalls anniversary of shuttered base

It has been 50 years this month since the announcement that Schilling Air Force Base was closing rattled Salina residents. The Salina Journal, which carried news of the closure in its Nov. 19, 1964, editions, reported that the economic disaster then spared no part of the community – real estate, retail, civic involvement, church attendance,...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>