Millihertz

Définitions de « millihertz »

Millihertz - Nom commun

• (Métrologie) Unité de mesure de fréquence correspondant à un millième de hertz (10−3 Hz), symbolisée par mHz.

  En s'aventurant dans les profondeurs de l'océan pour mesurer les ondulations les moins perceptibles des courants marins, les scientifiques utilisent des instruments calibrés en millihertz, révélant ainsi la subtile danse des eaux qui se meut à un rythme presque imperceptible.

Étymologie de « millihertz »

Évolution historique de l’usage du mot « millihertz » depuis 1800

Citations contenant le mot « millihertz »

• Similar to LIGO, LISA will detect gravitational waves by bouncing laser light along extended arms, measuring the minuscule variations in arms length. But while LIGO has arms just 4 kilometers long, LISA could have arms millions of kilometers long. Where LIGO can detect powerful transient bursts of gravitational waves with frequencies under a kilohertz, such as the mergers of black holes, LISA will detect millihertz waves and will be able to detect not just black hole mergers, but the gradual inspiraling of supermassive black holes and possibly even the remnant gravitational waves of the big bang.

• Astronomers from Australia and Taiwan report the discovery of millihertz quasi-periodic oscillations in a neutron-star low-mass X-ray binary known as 1RXS J180408.9−342058. The discovery, detailed in a paper published September 3 on the arXiv preprint server, could help astronomers better understand the nature and behavior of X-ray binary sources.

• Although scientists have observed ambient seismic noise for more than a century, free oscillations of Earth — vibrations with frequencies of 2 to 7 millihertz that are continuous and persist globally — were not discerned until the aftermath of the magnitude-9.5 earthquake that struck Chile in 1960, when scientists recorded standing waves in the solid earth. At the time, it was thought that Earth’s free oscillations were faint residual tectonic tremors left over from large earthquakes and that the phenomenon was transient.

• [Joseph] says doing the software side of things with Pure Data wasn’t a problem, but getting it out of the computer proved to be tricky. It turns out that your average computer sound card isn’t equipped to handle frequencies down into the millihertz range (big surprise), so they need to be coaxed out with some extra hardware. Using a simple circuit not unlike an AM demodulator, he’s able to extract the low-frequency signal from a 16 kHz carrier.

• LISA’s three constituent spacecraft will trail Earth in its orbit round the Sun in a triangular formation, each spacecraft separated from the other two by 2.5 million km. By directing laser light at each other, the spacecraft will act as a giant three-arm interferometer for detecting gravitational waves. LISA’s sweet spot is the millihertz band, which abounds in sources. Some types are expected, such as supermassive black hole binaries. But other, more exotic sources could show up, including gravitational waves generated during cosmic inflation.

Traductions du mot « millihertz »

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