Talk about a diet! By resolving, for the first time, features of an individual star in a neighbouring galaxy, ESO's VLT has allowed astronomers to determine that it weighs almost half of what was previously thought, thereby solving the mystery of its existence. The behemoth star is found to be surrounded by a massive and thick torus of gas and dust, and is most likely experiencing unstable, violent mass loss.
WOH G64 is a red supergiant star almost 2 000 times as large as our Sun and is located 163 000 light-years away in the Large Magellanic Cloud, one of the Milky Way's satellite galaxies.
"Previous estimates gave an initial mass of 40 times the mass of the Sun to WOH G64. But this was a real problem as it was way too cold, compared to what theoretical models predict for such a massive star. Its existence couldn't be explained," says Keiichi Ohnaka, who led the work on this object.
New observations, made with ESO's Very Large Telescope Interferometer, conclude that the gas and dust around the star is arranged in a thick ring, rather than a spherical shell, and the star is thus less hidden than had been assumed. This implies that the object is in fact half as luminous as previously thought, and thus, less massive. The astronomers infer that the star started its life with a mass of 25 solar masses. For such a star, the observed temperature is closer to what one would expect.
"Still, the characteristics of the star mean that it may be experiencing a very unstable phase accompanied by heavy mass loss," says co-author Markus Wittkowski from ESO. "We estimate that the belt of gas and dust that surrounds it contains between 3 and 9 solar masses, which means that the star has already lost between one tenth and a third of its initial mass."
To reach this conclusion, the team of astronomers used the MIDI instrument to combine the light collected by three pairs of 8.2-m Unit Telescopes of the VLT. This is the first time that MIDI has been used to study an individual star outside our Galaxy.
The observations allowed the astronomers to clearly resolve the star. Comparisons with models led them to conclude that the star is surrounded by a gigantic, thick torus, expanding from about 15 stellar radii (or 120 times the distance between the Earth and the Sun - 120 AU!) to more than 250 stellar radii (or 30 000 AU!).
"Everything is huge about this system. The star itself is so big that it would fill almost all the space between the Sun and the orbit of Saturn," says Ohnaka. "And the torus that surrounds it is perhaps a light-year across! Still, because it is so far away, only the power of interferometry with the VLT could give us a glimpse on this object. "
Henri Boffin | alfa
Liquid crystals in nanopores produce a surprisingly large negative pressure
25.04.2019 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
New robust device may scale up quantum tech, researchers say
25.04.2019 | Purdue University
Flexible, organic and printed electronics conquer everyday life. The forecasts for growth promise increasing markets and opportunities for the industry. In Europe, top institutions and companies are engaged in research and further development of these technologies for tomorrow's markets and applications. However, access by SMEs is difficult. The European project SmartEEs - Smart Emerging Electronics Servicing works on the establishment of a European innovation network, which supports both the access to competences as well as the support of the enterprises with the assumption of innovations and the progress up to the commercialization.
It surrounds us and almost unconsciously accompanies us through everyday life - printed electronics. It starts with smart labels or RFID tags in clothing, we...
The human eye is particularly sensitive to green, but less sensitive to blue and red. Chemists led by Hubert Huppertz at the University of Innsbruck have now developed a new red phosphor whose light is well perceived by the eye. This increases the light yield of white LEDs by around one sixth, which can significantly improve the energy efficiency of lighting systems.
Light emitting diodes or LEDs are only able to produce light of a certain colour. However, white light can be created using different colour mixing processes.
Researchers led by Francesca Ferlaino from the University of Innsbruck and the Austrian Academy of Sciences report in Physical Review X on the observation of supersolid behavior in dipolar quantum gases of erbium and dysprosium. In the dysprosium gas these properties are unprecedentedly long-lived. This sets the stage for future investigations into the nature of this exotic phase of matter.
Supersolidity is a paradoxical state where the matter is both crystallized and superfluid. Predicted 50 years ago, such a counter-intuitive phase, featuring...
A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter
A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.
Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...
17.04.2019 | Event News
15.04.2019 | Event News
09.04.2019 | Event News
25.04.2019 | Materials Sciences
25.04.2019 | Earth Sciences
25.04.2019 | Life Sciences