Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How stars grow into heavyweights

04.11.2015

Astronomers find a stable disk around a young, massive sun

Stars count lightweights and heavyweights among their number. All are born in clouds of gas and dust, but the more massive a baby star, the earlier nuclear fusion ignites in its core. And the radiation pressure produced here should really purge its surroundings and thus prevent the infall of matter which will allow the star to grow bigger. Some stars nevertheless manage to reach masses of more than a hundred times that of our Sun. How is this possible?


A star puts on weight: This artist’s impression shows the disk of gas and dust around the massive sun AFGL 4176.

© K. G. Johnston and ESO

Astronomers have believed for some time that disks around the infant stars play an important role in this process. A team of researchers including astronomers from the Heidelberg Max Planck Institute for Astronomy have now discovered such a stable structure around one of the most massive, newly forming stars in our galaxy.

The team headed by Katharine Johnston from the University of Leeds, and including the Max Planck astronomers Thomas Robitaille, Henrik Beuther, Hendrik Linz and Roy van Boekel, turned their sights on the object with catalogue number AFGL 4176. It is a very massive star in the southern constellation known as Centaurus, around 14,000 light years from Earth.

The star is in the process of being born, which is why its immediate environment is concealed within an envelope of gas and dust. The scientists observed the star in the millimetre and submillimetre range with the ALMA observatory of the European Southern Observatory (ESO), however – and looked behind the veil and into the interior of the envelope. They detected a disk-like, rotating structure.

To confirm this observation, the astronomers arranged a kind of identification parade: first they simulated more than 10,000 model disks with different properties. They then compared these images and spectra with the data obtained from nature. The best agreement was for a stable disk, where the gravitational effects of both the star and the disk material are important.

The radius of the disk surrounding AFGL 4176 is roughly 2000 times the average distance between the Earth and the Sun. The total mass is 12 solar masses – this corresponds to just under half the weight of the star itself, which is roughly 25 solar masses. The disk rotates around the star in a similar way to the planets around our Sun: the gas in the inner regions moves faster than that in the outer ones and obeys the laws discovered by Johannes Kepler at the beginning of the 17th century.

These Keplerian disks could play a key role in the growth of massive stars and particularly explain how enough additional matter can accrete despite the substantial radiation pressure exerted by the young star. One factor is that a stable disk of this type can direct enormous amounts of matter onto the nascent star; another is that it presents a very narrow profile to the radiation pressure and thus a much smaller area of attack than gas which surrounds the star like a spherical shell.

Astronomers had previously been unable to detect stable disks around the most massive stellar embryos (O-type stars) with certainty. It was therefore unclear whether these disks were possible explanations at all.

The observations by Katharine Johnston and her colleagues, in contrast, show that at least one of the most massive stars can be formed in the same way as its less massive relatives: through mechanisms which are the same as those of less massive stars despite differences in scales and in timing; and with matter which is funnelled onto the growing infant star by a Keplerian disk.

The high quality of the ALMA observations raises expectations that it will also be possible to clarify further important, unanswered questions about the formation of massive stars. The astronomers hope for information about one feature in particular: very massive stars are nearly always members of twin or multiple star systems. High-resolution images of the innermost regions in the early phases of star birth could show directly how the precursors of the different components of such a system form.


Contact

Dr. Markus Pössel
Max Planck Institute for Astronomy, Heidelberg
Phone: +49 6221 528-261

Email: poessel@mpia.de

 
Dr. Henrik Beuther
Max Planck Institute for Astronomy, Heidelberg
Phone: +49 6221 528-447

Email: beuther@mpia.de

Dr. Thomas Robitaille
Max Planck Institute for Astronomy, Heidelberg
Phone: +49 6221 528-395

Email: robitaille@mpia.de


Original publication
Johnston et al.
A Keplerian-like disk around the forming O-type star AFGL 4176
Astrophysical Journal Letters, 29 October 2015

Source

Dr. Markus Pössel | Max Planck Institute for Astronomy, Heidelberg
Further information:
https://www.mpg.de/9723445/massive-star

More articles from Physics and Astronomy:

nachricht New research identifies how 3-D printed metals can be both strong and ductile
11.12.2017 | University of Birmingham

nachricht Three kinds of information from a single X-ray measurement
11.12.2017 | Friedrich-Schiller-Universität Jena

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: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

Im Focus: Virtual Reality for Bacteria

An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications

Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...

Im Focus: A space-time sensor for light-matter interactions

Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.

The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

Blockchain is becoming more important in the energy market

05.12.2017 | Event News

 
Latest News

New research identifies how 3-D printed metals can be both strong and ductile

11.12.2017 | Physics and Astronomy

Scientists channel graphene to understand filtration and ion transport into cells

11.12.2017 | Materials Sciences

What makes corals sick?

11.12.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>