Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Uncloaking the King of the Milky Way: The largest star in our home galaxy's largest stellar nursery

28.08.2014

Astronomers led by Shiwei Wu of the Max Planck Institute for Astronomy have identified the most massive star in our home galaxy's largest stellar nursery, the star-forming region W49.

The star, named W49nr1, has a mass between 100 and 180 times the mass of the Sun. Only a few dozen of these very massive stars have been identified so far. As seen from Earth, W49 is obscured by dense clouds of dust, and the astronomers had to rely on near-infrared images from ESO's New Technology Telescope and the Large Binocular Telescope to obtain suitable data. The discovery is hoped to shed light on the formation of massive stars, and on the role they play in the biggest star clusters.


An infrared colour composite image of the central area of W49. The massive star W49nr1 is indicated with a white arrow.

S.-W. Wu, A. Bik, Th. Henning, A. Pasquali, W. Brandner, A. Stolte. J and H-band data originally published in Alves and Homeier 2003.

The discovery of a new, very massive star is exciting to astronomers for more than one reason: Very massive stars, more than 100 times the mass of our own Sun, are something of an astronomical mystery. They are very short-lived (a few million years compared to the 10 billion years of stars like our Sun), which is one reason they are so rare. Among the billions of stars catalogued and examined by astronomers, these very massive specimens amount to no more than a few dozen, most of them discovered over the past few years.

Though rare, the massive stars have a decisive influence on their surroundings. They are extremely bright, giving off large amounts of highly energetic UV radiation as well as streams of particles (stellar wind). Typically, such a star will create a bubble around itself, ionizing any nearby gas, and pushing more distant gas ever farther away. Some of this pushed-away gas might actually cause distant gas clouds to collapse, triggering the birth of new stars.

Until a few years ago, there was even doubt whether such stars could form at all. Theorists have only quite recently managed to simulate the genesis of these massive bodies, and there are now several competing explanations for very massive star formation. In some models, such a star is the result of the merger between two stars forming in an extended star cluster. Up to now, there had only been three clusters (NGC 3603 and the Arches Cluster in our galaxy, R136 in the Large Magellanic Cloud) where such massive stars had actually been found.

Now, a team of astronomers lead by Shiwei Wu from the Max Planck Institute for Astronomy (MPIA) has discovered such a massive star, and not in any location, but in the largest star-forming region known in our Milky Way galaxy, which is called W49. The discovery was a challenging task: W49 is located at a distance of 36,000 light-years (11.1 kpc), almost half-way across our home galaxy, cloaked by the dust of two spiral arms that lie between us and the cluster.

Shiwei Wu explains: „Because W49 is hidden behind huge regions of interstellar dust, only one trillionth of the visible light it sends in our direction actually reaches Earth. That’s why we observed the cluster’s infrared light, which can pass through dust almost unhindered.”

Using a spectrum obtained with the European Southern Observatory’s Very Large Telescope in the infrared, the astronomers could determine the star’s type (“O2-3.5If* star”) and use this information and the star’s measured brightness to estimate its temperature and total light emission. Comparison with models for stellar evolution give an estimate of the star’s mass between 100 and 180 solar masses.

Because of the cluster’s size, W49 is one of the most important sites within our galaxy for studying the formation and evolution of very massive stars – and with W49nr1, the astronomers have now identified the cluster’s key object. With this and future observations, they have hopes of settling one of astronomy’s weightiest open questions: the birth of our galaxy’s most massive stars.

Contact

Shiwei Wu (first author)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 –528 203
email: shiwei@mpia.de

Klaus Jäger (public information officer)
Max Planck Institute for Astronomy
Heidelberg, Germany
Phone: (+49|0) 6221 – 528 379
email: pr@mpia.de

Background information

Further images and the original press release can be found here:

http://www.mpia.de/Public/menu_q2e.php?Aktuelles/PR/2014/PR_2014_07/PR_2014_07_e...

The results described here have been published as S.-W. Wu et al., “The Discovery of a Very Massive Star in W49” by the journal Astronomy & Astrophysics.

http://dx.doi.org/10.1051/0004-6361/201424154

The co-authors are Shi-Wei Wu (Max Planck Institute for Astronomy [MPIA]), Arjan Bik (MPIA and Stockholm University), Thomas Henning (MPIA), Anna Pasquali (ZAH, Heidelberg University), Wolfgang Brandner (MPIA) and Andrea Stolte (Argelander Institute for Astronomy, Bonn).

The study is based on a medium-resolution K-band spectrum taken with the ISAAC instrument mounted at ESO's Very Large Telescope in Chile. Infrared images were obtained with SOFI at the New Technology Telescope at ESO's La Silla Observatory (J- and H-Band), and with LUCI mounted at the Large Binocular Telescope in Arizona (K-Band).

Dr. Klaus Jäger | Max-Planck-Institut

Further reports about: Astronomie Astronomy Earth MPIA Max-Planck-Institut Sun Technology Telescope images

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>