The biggest digital map of the universe yet

The biggest digital map of the universe yet
On the summit of Haleakala, a dormant volcano on the island of Maui in Hawaii, USA, a telescope began clicking pictures of the night sky in 2010. Over the next four years, Pan-STARRS, short for Panoramic Survey Telescope and Rapid Response System or Pan-STARRS, photographed the entire sky, as seen from Hawaii, 12 times in five colours of visible and infrared light.

In December 2016, the astronomers who operate Pan-STARRS released the first results from their survey. Their big data universe lists the positions, colours and brightness of three billion stars, galaxies and other objects. It amounts to two petabytes of data, roughly equivalent to one billion selfies, according to a statement from the University of Hawaii’s Institute for Astronomy.

All this information, the universe in a box, resides in the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute in Baltimore where any astronomer can access it. In 2017, the Pan-STARRS team plans to produce a new catalogue of how these things are moving and changing. This was an exercise in more than just curiosity.

A big goal of the project, run by an international consortium led by the University of Hawaii, is to discover moving objects like asteroids so that we can visit them and perhaps steer them away before they visit us, as well as to discover supernovas and other rare violent events while they are exploding. Pan-STARRS is the biggest digital mapping effort yet done, but it is not the last.

Dennis Overbye

The burst of bubbles, decoded

A cork pops. The sudden change in pressure in the bottle releases carbon dioxide. Bubbles form. Once in a glass, a million of them cling to its edges before rising to the top and bursting. The explosions release tiny droplets that dart across your tongue. This may be how you welcomed 2017.

In an issue of the European Physical Journal Special Topics released this month, researchers follow carbon dioxide from where it first forms in harvested grapes until it bursts in your glass. Thomas Seon, a physicist at Pierre and Marie Curie University in France, and his colleagues found that each bubble’s spray has droplets full of intense aromas and flavours. An aroma can vary, depending on bubbling speed, a single bubble’s size, temperature of the liquid and even the shape of the glass. While some believe tiny bubbles flowing constantly improve the taste, researchers say big bubbles actually release more aromatic spray.

Joanna Klein

It’s all about the wood for these violins

For centuries, many of the best violinists have preferred a Stradivari or a Guarneri. Why nobody has been able to replicate the coveted sound of those instruments, made in the small village of Cremona, Italy, in the late 17th and early 18th centuries, remains a mystery. A study in the Proceedings of the National Academy of Sciences found that mineral treatments, centuries of ageing and transformation from playing, might have created unique tonal qualities.

The study noted evidence of aluminium, calcium, copper and other elements in wood shavings from the instruments. “This paper is the first to convince me that some type of mineral infusion into wood might cause superior sound in a musical instrument,” said Henri Grissino-Mayer, a geography professor at the University of Tennessee, Knoxville, who was not involved in the research.

The researchers also discovered that one-third of an absorbent wood component known as hemicellulose had decomposed in Stradivari and Guarneri’s instruments, leaving them with about 25% less water than more recent models. Stradivari and Guarneri instruments have rich bass tones and a quality known as brilliance — able to project a clean, high-frequency sound.

Researchers also found an extra peak in oxidation when they heated the wood shavings of the violins, which suggests a detachment between wood fibres. This detachment, possibly the result of centuries of vibrations from playing, may give the instruments greater expressiveness, said Hwan-Ching Tai, lead author of the study. As the instruments continue to decompose, many will lose their precious acoustics, Hwan-Ching said. “These instruments will not last forever.”

Steph Yin

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