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 Temperature-controlled fiber-optic light source with liquid core
20.06.2018 | Leibniz-Institut für Photonische Technologien e. V.

nachricht New material for splitting water
19.06.2018 | American Institute of Physics

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: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Better model of water under extreme conditions could aid understanding of Earth's mantle

21.06.2018 | Earth Sciences

What are the effects of coral reef marine protected areas?

21.06.2018 | Life Sciences

The Janus head of the South Asian monsoon

21.06.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>