* Astronomy

Members Login
Post Info
TOPIC: The first stars


L

Posts: 131433
Date:
HE 1523-0901
Permalink  
 


HE 1523-0901 is the designation given to a red giant star  located in the Milky Way galaxy approximately 750 light years away. It is thought to be a second generation Population II, or metal-poor, star ([Fe/H]=-2.95). The star was found in the sample of bright metal-poor halo stars from the Hamburg/ESO Survey by Anna Frebel and collaborators. The group's research was published in the May 10 2007 issue of the Astrophysical Journal.
The star's age, as measured by ESO's Very Large Telescope, is 13.2 billion years. This makes it the oldest object yet discovered in the galaxy, and nearly as old as the estimated age of the universe itself (13.7 billion years as measured by WMAP).

Read more

__________________


L

Posts: 131433
Date:
Cosmic Dark Ages
Permalink  
 


The details surrounding the end of the dark ages are among the final unknowns in modern astronomy.
The Cosmic Dark Ages, a public astronomy lecture exploring how starlight from the first galaxies lit up the Universe, will be presented by Swinburne researcher Dr Emma Ryan-Weber at the university's Hawthorn campus on Friday 16 April.

Read more

__________________


L

Posts: 131433
Date:
RE: The first stars
Permalink  
 


When the very first stars lit up, they may have been fuelled by the dark matter that has long eluded scientists.
These "dark stars," first born nearly 13 billion years ago, might still exist today. Although they would not shed any visible light, astronomers might detect these invisible giants - some 400 to 200,000 times wider than our sun and 500 to 1,000 times more massive - because they should spew gamma rays, neutrinos and antimatter and be linked with clouds of cold, molecular hydrogen gas that normally would not harbour such energetic particles.

Read more

__________________


L

Posts: 131433
Date:
Population III stars
Permalink  
 


Research by a Michigan State University scientist sheds new light on how stars and galaxies were formed back in the early days of the universe - some 13 billion years ago.
Work by Brian O'Shea, an MSU assistant professor of physics and astronomy, and two colleagues indicates that the universe's earliest inhabitants, known as Population III stars, were not nearly as massive as originally thought. In addition, they argue that many of these stars actually formed in binary systems, that is, pairs of stars that orbit a common center.
The research will be published in the journal Science, and will appear on the Web site Science Express July 9.

Read more

__________________


L

Posts: 131433
Date:
RE: The first stars
Permalink  
 


Simulations Illuminate Universe's First Twin Stars
The earliest stars in the universe formed not only as individuals, but sometimes also as twins, according to a paper published today in Science Express. By creating robust simulations of the early universe, astrophysicists Matthew Turk and Tom Abel of the Kavli Institute for Particle Astrophysics and Cosmology, located at the Department of Energy's SLAC National Accelerator Laboratory, and Brian O'Shea of Michigan State University have gained the most detailed understanding to date of the formation of the first stars.

"We used to think that these stars formed by themselves, but now we see from our computer simulations that sometimes they have siblings. These stars provide the seeds of next generation star formation, so by understanding them we can better understand how other stars and galaxies formed" - Matthew Turk.

To make this discovery, the researchers created an extremely detailed computer simulation of early star formation. Into this virtual universe they sprinkled primordial gas and dark matter as it existed soon after the Big Bang, data they obtained from observations of the cosmic microwave background. This mostly uniform radiation - a faint glow of radio waves spread across the entire sky - contains subtle variations that reflect the beginning of all structure in the universe.

Read more

__________________


L

Posts: 131433
Date:
Permalink  
 

It was snap, crackle and pop in the early days of the universe. You would not want to live there. Astronomers said Tuesday that they had smashed the long-distance record in astronomy when they recorded an explosion, probably a massive early star, that lived and died 13 billion years ago, only about 600 million years after the Big Bang.

Read more 


__________________


L

Posts: 131433
Date:
Permalink  
 

Dans un quasar très éloigné, énorme formation détoiles aux limites des lois physiques

Comment les premières étoiles ont été formées ? Des indications concrètes ont été trouvées pour la première fois par une équipe internationale  de chercheurs, dont un directeur de recherche du CNRS. En observant l'une des galaxies les plus éloignées connue à ce jour (un quasar formé moins d'un milliard d'années après le Big Bang) ils ont réussi à dénicher un nombre gigantesque d'étoiles en son coeur, un chiffre si énorme qu'il approche les limites des lois physiques. Cette découverte est d'autant plus intéressante qu'elle réfute une théorie longtemps nourrie selon laquelle les premières étoiles se seraient formées de manière dispersée dans tout le volume des jeunes galaxies. La détection a pu être réalisée grâce à l'interféromètre du Plateau de Bure de l'IRAM (Institut de Radioastronomie Millimétrique : CNRS-INSU, MPG, IGN) dans les Hautes-Alpes.

Read more  (French)

__________________


L

Posts: 131433
Date:
Permalink  
 

A team of NASA-funded scientists, including two from UC Santa Barbara, have discovered cosmic radio noise that they find completely unexpected and exciting.
The finding came from data collected from a large helium-filled NASA balloon, big enough to fit a football field inside. The scientists discovered cosmic radio noise that is blasting six times louder than expected.

"It seems as though we live in a darkened room and every time we turn the lights on and explore, we find something new. The universe continues to amaze us and provide us with new mysteries. It is like a large puzzle that we are slowly given pieces to so that we can eventually see through the fog of our confusion" - team member Philip M. Lubin, professor of physics at UCSB.


Read more

__________________


L

Posts: 131433
Date:
Permalink  
 

When the universe was still young, they were already dying.
The first stars ever to grace the cosmos with light were brutish monsters, so the story believed by most astronomers goes, lumbering clouds of hydrogen and helium hundreds of times more massive than the Sun. They lived fast and bright and died hard, exploding or collapsing into massive black holes less than a billion years after the Big Bang, never to be seen again.
But they might have left something behind, a buzz of radio waves emitted by high-energy particles spit from the doomed gas swirling around those black holes.
Has that buzz, a cry from the vanished ancestors of our Sun, now been heard?


Read more


__________________


L

Posts: 131433
Date:
Permalink  
 

Title: Protostar Formation in the Early Universe
Authors: Naoki Yoshida (Nagoya University), Kazuyuki Omukai (NAOJ), Lars Hernquist (CfA-Harvard)
(Version v2)

The nature of the first generation of stars in the Universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass of just one percent that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

Read more  (386kb, PDF)

__________________
«First  <  1 2 3 4 5 6  >  Last»  | Page of 6  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard