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Pulsating stars that reveal the motion of spiral galaxies are called cepheid variables. Cepheids are bright, yellowish stars that pulsate regularly, varying in brightness by up to a factor of 100 over periods of a few days to several months. Astronomers use cepheids to study the rotation of spiral galaxies by measuring the velocities of cepheids at different locations in the galaxy. The velocities of cepheids can be measured by observing their Doppler shifts.The Doppler effect is the apparent change in frequency of a wave in relation to an observer moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842. The Doppler effect can be observed with any type of wave, including sound waves, light waves, and water waves. The Doppler effect can also be used to measure the speed of moving objects. For example, astronomers use the Doppler shift of light from stars and galaxies to measure their velocities. This informa...

  The Very Large Telescope (VLT) in Chile has confirmed the existence of an exoplanet lurking in a 3-body star system. The exoplanet, which is 15 times more massive than Jupiter, is orbiting a small star that itself orbits a larger star. Also orbiting the larger star is a brown dwarf, or "failed" star. This discovery is significant because it is the first time that an exoplanet has been directly imaged in a 3-body star system. It also provides astronomers with new insights into the formation of complex planetary systems. The VLT was able to detect the exoplanet by using a technique called direct imaging. In this technique, astronomers use powerful telescopes to take images of stars and look for signs of planets orbiting them. In the case of the newly discovered exoplanet, astronomers were able to see a faint blob of light orbiting the small star. The discovery of this exoplanet is an exciting development for astronomers, and it shows the power of the VLT to study planets beyo...