Large spiral galaxies, such as our neighbour the Andromeda Galaxy, leave virtually no gas or dust particles unused during the formation of stars. Dutch astronomers calculated this based on the rotational speeds of more than one hundred nearby galaxies. The large galaxies achieve an efficiency of 80 to 100% and are therefore far more efficient than the maximum of 20% attributed to the previous record holders: medium-sized galaxies such as our Milky Way.

Published by the editorial team, 3 June 2019

The new calculations also have implications for what is called the missing normal matter. For a long time, researchers have assumed that the universe consists of about 5% normal matter, such as atoms and molecules, and of 95% dark, unknown matter and dark, unknown energy. In addition, the majority of that 5% normal matter was missing. According to the new calculations, however, scarcely any normal matter is missing in the large spiral galaxies.

Scientists are now adjusting the theory to reflect the new findings. Finding some of the missing normal matter was a relief. However, the fact that large galaxies form stars far more efficiently than previously thought will give rise to other problems.

Andromeda Galaxy

NGC 5371 is an example of a very efficient spiral galaxy. It is located about 100 million light years from Earth in the constellation Canes Venatici, which lies near the constellation Ursa Major. It is one of the heaviest of the more than 100 galaxies investigated. The galaxy contains almost no missing normal matter and has used virtually all of the dust and gas to produce stars. The Andromeda Galaxy, our nearest neighbour at just 2.5 million light years from Earth, also proved to be highly efficient.

The research was carried out by Lorenzo Posti (University of Groningen and University of Strasbourg, France), Filippo Fraternali (University of Groningen) and Antonino Marasco (University of Groningen and ASTRON) and will soon be published in the journal Astronomy and Astrophysics.


Peak star formation efficiency and no missing baryons in massive spirals. By Lorenzo Posti (University of Groningen and University od Strasbourg France), Filippo Fraternali (University of Groningen) & Antonino Marasco (University of Groningen and ASTRON). Accepted for publication in Astronomy & Astrophysics. (free preprint)


The spiral galaxy NGC 5371 is highly efficient and contains almost no missing normal matter. (c) SDSS/Fraternali



Original press release here (in Dutch only).


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On June 13-17, the LOFAR Family Meeting took place in Cologne. After two years LOFAR researchers could finally meet in person again. The meeting brings together LOFAR users and researchers to share new scientific results.

Our renewed ‘Melkwegpad’ (Milky Way Path) is finished! The new signs have texts in Dutch on the one side and in English on the other side. The signs concerning planets have a small, 3D printed model of that planet in their centre.
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The background drawing shows how the subband correlator calculates the array correlation matrix. In the upper left the 4 UniBoard2s we used. The two ACM plots in the picture show that the phase differences of the visibilities vary from 0 to 360 degrees.

Daily image of the week: Testing with the Dwingeloo Test Station (DTS)
One of the key specifications of LOFAR2.0 is measuring using the low- and the highband antenna at the same time. For this measurement we used 9 lowband antenna and 3 HBA tiles.