Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More star births than astronomers have calculated

02.10.2008
More newborn stars are apparently emerging around the universe than previously assumed. Researchers at Bonn University have now published a paper in the prominent science journal “Nature” explaining this discrepancy. Their study has identified a systematic error in the method of estimation.

The “birth rate” for stars is certainly not easy to determine. Distances in the universe are far too great for astronomers to be able to count all the newly formed celestial bodies with the aid of a telescope. So it is fortunate that the emerging stars give themselves away by a characteristic signal known as “H-alpha” emissions. The larger the number of stars being formed in a particular region of the firmament, the more H-alpha rays are emitted from that region.

“H-alpha emissions only occur in the vicinity of very heavy stars,” explains Jan Pflamm-Altenburg of the Argelander Institute of Astronomy at Bonn University. It has long been accepted that heavy and light stars are always born in a certain ratio to each other. One “H-alpha baby” is thought to be accompanied by 230 lighter stars with a mass too low for them to emit H-alpha rays.

However, new observations make this theory untenable. On the edges of “disc galaxies” (like the Milky Way) the H-alpha radiation ceases abruptly. For a long time astronomers concluded from this finding that no stars are being born in this region. “The explanation offered is simply that too little gaseous matter exists for it to collapse into balls and form stars,” says Jan Pflamm-Altenburg. “These theories largely inform our understanding of how galaxies developed from the Big Bang to the present.”

Satellite mission baffles astronomers

A satellite mission has recently revealed that stars are in fact being formed beyond the H-alpha perimeter. These stars are, without exception, so light that no H-alpha radiation is emitted. Consequently, the numerical ratio of 230 light stars to one heavy star does not apply to the edges of galaxies. “This observation presented the astronomy community with quite a conundrum,” says Professor Dr. Pavel Kroupa of the Argelander Institute.

Kroupa and Pflamm-Altenburg have come up with a solution which, they say, is basically very simple. They note that star births are not evenly distributed across galaxies but are focused on the star clusters – well known examples being the Seven Sisters and the Orion Nebula. And only large, high-mass clusters produce heavy stars, i.e. the newborn stars that can create the H-alpha emission. “But these heavy star clusters primarily occur in the core regions of disc galaxies,” says Jan Pflamm-Altenburg. “Towards the edges they become increasingly rare. The outer regions tend to contain smaller clusters in which the formation of lighter stars is more frequent.”

The conclusion is that a numerical ratio of 230 to 1 is only valid for the centres of galaxies. On the edges of galaxies each “H-alpha baby” might be accompanied by a thousand or more light stars. Those astronomers who always use the same factor when calculating total star formations from their H-alpha readings therefore underestimate the number of newborn stars.

The theoretical work of the two Bonn-based astrophysicists supports affirms that the mass of new stars depends linearly on the mass of the gas in their vicinity. Their conclusions open up completely new perspectives for research into the development of galaxies.

Contact:
Jan Pflamm-Altenburg
Argelander-Institut für Astronomie, University of Bonn
Telephone: 0228/73-5656
E-mail: jpflamm@astro.uni-bonn.de
Professor Dr. Pavel Kroupa
Argelander-Institut für Astronomie, University of Bonn
Telephone: 0177/9566127
E-mail: pavel@astro.uni-bonn.de

Prof. Dr. Pavel Kroupa | alfa
Further information:
http://www.astro.uni-bonn.de

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Massive impact crater from a kilometer-wide iron meteorite discovered in Greenland

15.11.2018 | Earth Sciences

When electric fields make spins swirl

15.11.2018 | Physics and Astronomy

Discovery of a cool super-Earth

15.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>