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.


 
 

 
NASA photograph by Dimitri Gerondidakis

NASA’s Orion spacecraft, rocket move closer to first flight

NASA photograph by Dimitri Gerondidakis The United Launch Alliance Delta IV Heavy rocket that will send NASA’s Orion spacecraft on its first flight test in December was moved to its vertical launch position Oct. 1 at Space La...
 
 
lm-orion3

Orion spacecraft transfers To launch abort system facility

https://www.youtube.com/watch?v=j68mszdhTmY NASA and Lockheed Martin have finished fueling the Orion spacecraft with ammonia, hydrazine and high pressure helium at Kennedy Space Center’s Payload Hazardous Servicing Facili...
 
 

NASA telescopes find clear skies, water vapor on exoplanet

Astronomers using data from three of NASA’s space telescopes – Hubble, Spitzer and Kepler – have discovered clear skies and steamy water vapor on a gaseous planet outside our solar system. The planet is about the size of Neptune, making it the smallest planet from which molecules of any kind have been detected. “This discovery...
 

 
NASA photograph by Aubrey Gemignani

New crew launches to space station to continue scientific research

NASA photgoraph Three crew members are heading to the International Space Station after launching in a Soyuz spacecraft from the Baikonur Cosmodrome in Kazakhstan at 4:25 p.m., EDT, Sept. 25. Three crew members representing the...
 
 

NASA expands commercial space program, requests proposals for IS resupply

On the heels of awarding groundbreaking contracts to U.S. commercial space companies to ferry American astronauts to the International Space Station, NASA has released a request for proposals for the next round of contracts for private-sector companies to deliver experiments and supplies to the orbiting laboratory. Under the Commercial Resupply Services 2 RFP, NASA intends...
 
 

ATK offers solid solution to U.S. Air Force’s RD-180 replacement request

ATK has provided the U.S. Air Force an American-made commercial solid rocket solution as a replacement for the RD-180 Russian-made, first-stage engine of United Launch Alliance’s Atlas V launch vehicle. “ATK’s solid rocket propulsion solution provides a cost-effective, reliable solution based on advanced technology,” said Blake Larson, president of ATK’s Aerospace ...
 




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>