Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Absence of Stellar Pulsations Baffles Astronomers

23.08.2004


Readings done by a Canadian-Austrian team present a puzzle for astronomers. Expected surface phenomena, which provide information about stellar structures, could not be evidenced from readings obtained by means of a Canadian microsatellite. The precise satellite readings leave no doubt on the data published in NATURE. The project, organised in co-operation with the Institute of Astronomy at the University of Vienna and supported by the Austrian Science Fund (FWF), challenges the existing understanding of the structure of stars.

The phenomenon of pressure-driven oscillations at the surface of the sun has been known for more than 25 years. Astronomers use these pulsations to gain knowledge on the structure of the sun. Prof. Werner W. Weiss and his team from the Institute for Astronomy at the University of Vienna together with a Canadian team could for the first time conduct such observations on another star using a Canadian microsatellite. But contrary to all findings of terrestrial studies and previous calculations, there is no evidence for the surface pulsations.

"Good Vibrations" of the Stars



Prof. Weiss illustrates the astronomers’ interest in the surface pulsations thus: "It sounds paradoxical, but the surface pulsations provide us with knowledge of stellar structures. Just as seismology explores the interior of the earth by measuring quakes, the new discipline known as asteroseismology analyses the surface pulsations of stars to study their structures." One uses oscillations caused by these pulsations that move to the stellar core, where they are reflected and thrown back to the surface. The oscillations vary according to the nature of the surroundings and are measurable, thus providing indirect information about the interior of a star.

However, the surface pulsations cannot be directly measured. So the asteroseismologists measure the slight variations in the light intensity caused by these pulsations. The newest tool to be employed in this study is the Canadian microsatellite known as MOST (Microvariability and Oscillations of Stars) that is managed by Prof. Jaymie Matthews at the University of British Columbia, Canada. The satellite is situated 820 km above the earth and measures the light intensity of remote stars.

"The earth’s atmosphere is really cumbersome for measuring light. It works like a filter. MOST avoids this problem with a telescope that penetrates deep into space. Thus with a telescope of aperture 15 cm, we can achieve a higher precision in observation of a bright star than with an eight-metre telescope from earth," explains Prof. Weiss. The precision of the satellite telescope was actually confirmed by control surveys, which data was also received by a Viennese earth station, financed by the Austrian Space Agency and developed by the Vienna University of Technology.

Contradictory Findings = New Questions

The MOST’s first object for readings was Procyon, a star that lies in the constellation of Orion when viewed from the earth. Seven independent readings from the earth as well as theoretical calculations anticipated a minimum of 0.002% of oscillations of light intensity caused by pulsations, which was not a problem for MOST that can read oscillations up to 0.0003%. For all the precision, no significant surface oscillations could be determined for Procyon.

Prof. Weiss states: "This finding has interesting consequences for astronomy. It is possible that other gaseous movements, created by temperature differences at the surface of the star, cause an interfering signal that is superimposed on our readings. Then our data will be exceptionally valuable for future readings. It can also be that we must review our model calculations."

Astronomers would then be required to critically question the current knowledge about the inner structure of stars. The fact that even a budding specialist discipline such as asteroseismology challenges the foundation of a scientific area is a significant point for FWF. For it assuredly advances its adherence to creativity, quality and innovation as the most important criteria for funding.

Till C. Jelitto | alfa
Further information:
http://www.prd.at
http://www.astro.univie.ac.at
http://www.fwf.ac.at

More articles from Physics and Astronomy:

nachricht Physicists from Hannover Predict Novel Light Molecules
26.02.2020 | Leibniz Universität Hannover

nachricht From China to the South Pole: Joining forces to solve the neutrino mass puzzle
25.02.2020 | Johannes Gutenberg-Universität Mainz

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: High-pressure scientists in Bayreuth discover promising material for information technology

Researchers at the University of Bayreuth have discovered an unusual material: When cooled down to two degrees Celsius, its crystal structure and electronic properties change abruptly and significantly. In this new state, the distances between iron atoms can be tailored with the help of light beams. This opens up intriguing possibilities for application in the field of information technology. The scientists have presented their discovery in the journal "Angewandte Chemie - International Edition". The new findings are the result of close cooperation with partnering facilities in Augsburg, Dresden, Hamburg, and Moscow.

The material is an unusual form of iron oxide with the formula Fe₅O₆. The researchers produced it at a pressure of 15 gigapascals in a high-pressure laboratory...

Im Focus: From China to the South Pole: Joining forces to solve the neutrino mass puzzle

Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics

Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the Cluster of Excellence PRISMA+ at...

Im Focus: Therapies without drugs

Fraunhofer researchers are investigating the potential of microimplants to stimulate nerve cells and treat chronic conditions like asthma, diabetes, or Parkinson’s disease. Find out what makes this form of treatment so appealing and which challenges the researchers still have to master.

A study by the Robert Koch Institute has found that one in four women will suffer from weak bladders at some point in their lives. Treatments of this condition...

Im Focus: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Scientists develop algorithm for researching evolution of species with WGD

26.02.2020 | Information Technology

MOF co-catalyst allows selectivity of branched aldehydes of up to 90%

26.02.2020 | Life Sciences

Structural framework for tumors also provides immune protection

26.02.2020 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>