Featured Research

from universities, journals, and other organizations

New Theory Finds Middle Ground Between Conflicting Evidence For First Stars

Date:
June 2, 2004
Source:
University Of Chicago
Summary:
The very first stars that formed early in the history of the universe were smaller than the massive giants implied by the results of a NASA research satellite, but still larger than the typical stars found in our galaxy today, according to a research team led by the University of Chicago's Jason Tumlinson.

Credit: Image courtesy Jason Tumlinson, University Of Chicago

The very first stars that formed early in the history of the universe were smaller than the massive giants implied by the results of a NASA research satellite, but still larger than the typical stars found in our galaxy today, according to a research team led by the University of Chicago's Jason Tumlinson.

"We have managed to reconcile within a single theory the two very different leading indicators of the nature of the first stars," said Tumlinson, the Edwin Hubble Scientist in Astronomy & Astrophysics at the University of Chicago. Tumlinson will present the theory June 1 at the American Astronomical Society meeting in Denver. His co-authors are the University of Colorado's Aparna Venkatesan and J. Michael Shull.

No telescope is powerful enough yet to see the first stars, but astronomers can guess at their existence based on the stellar clues they leave behind. In 2001 and 2002, NASA's Wilkinson Microwave Anistropy Probe (WMAP) looked at the oldest light in the universe left over from the big bang, the cosmic microwave background, and found one such clue in the form of ionized (electrically charged) gas floating between the galaxies. WMAP showed that this intergalactic gas was ionized approximately 200 million years after the big bang.

"Very massive stars, with roughly 200 to 500 times the mass of the sun, and more massive than we see anywhere today, are extremely efficient at producing this ionizing radiation," Tumlinson said. This implies that the earliest stars were massive enough to cause the ionization.

But the oldest stars in our galaxy that astronomers can see in the sky today are on average approximately 13 billion years old. "They would have formed just after the first stars and out of the very gas and heavy elements that were strewn into space when the earliest stars exploded as supernovae," said Venkatesan, a National Science Foundation Fellow at Colorado and 2000 University of Chicago Ph.D. alumna.

The problem is that the ratio of heavy elements observed in the second generation of stars could not have been produced in the most massive stars associated with the WMAP studies.

"It was our goal to reconcile these two conflicting pieces of evidence," Tumlinson said.

His team reconciled the evidence by formulating a theory showing how stars with a mass of 20 to 100 times that of the sun could both be large enough to satisfy the WMAP results, yet still produce the ratio of heavy elements detected by ground-based telescopes in very old stars.

"We're not saying the very massive stars couldn't have formed at some low level. We're saying that for early heavy element production you need mostly stars that are massive but not extremely massive."

This theory meshes well with what astronomers know about how stars of various masses form in the galaxy.

"There are a lot of very low-mass stars like the sun, and as you go up in stellar mass, the numbers get more rare," Tumlinson said. "There are a very few stars of high mass, say a hundred solar masses in our galaxy. According to our theory, these massive stars were much more common in the first generation."

Problems that remain to be solved include determining how long the conditions could be maintained for forming the first stars from primordial gas and how these objects can be detected in the future, Venkatesan said.

"Predicting how the first stars affect their environment and whether they resemble the stars in our own galactic backyard at all is a critical input for the planning of future telescopes and instruments and in interpreting their data," she said.

The project was funded by NASA and the National Science Foundation.


Story Source:

The above story is based on materials provided by University Of Chicago. Note: Materials may be edited for content and length.


Cite This Page:

University Of Chicago. "New Theory Finds Middle Ground Between Conflicting Evidence For First Stars." ScienceDaily. ScienceDaily, 2 June 2004. <www.sciencedaily.com/releases/2004/06/040602062725.htm>.
University Of Chicago. (2004, June 2). New Theory Finds Middle Ground Between Conflicting Evidence For First Stars. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2004/06/040602062725.htm
University Of Chicago. "New Theory Finds Middle Ground Between Conflicting Evidence For First Stars." ScienceDaily. www.sciencedaily.com/releases/2004/06/040602062725.htm (accessed July 22, 2014).

Share This




More Space & Time News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Cargo Craft Undocks from Space Station

Raw: Cargo Craft Undocks from Space Station

AP (July 22, 2014) A Russian Soyuz cargo-carrying spacecraft undocked from the International Space Station on Monday. The craft is due to undergo about ten days of engineering tests before it burns up in the Earth's atmosphere. (July 22) Video provided by AP
Powered by NewsLook.com
NASA Ceremony Honors Moon Walker Neil Armstrong

NASA Ceremony Honors Moon Walker Neil Armstrong

AP (July 21, 2014) NASA honored one of its most famous astronauts Monday by renaming a historic building at the Kennedy Space Center in Florida. It now bears the name of Neil Armstrong, the first man to walk on the moon. (July 21) Video provided by AP
Powered by NewsLook.com
Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com
This Week @ NASA, July 18, 2014

This Week @ NASA, July 18, 2014

NASA (July 18, 2014) Apollo 11 yesterday, Next Giant Leap tomorrow, Science instruments for Europa mission, and more... Video provided by NASA
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins