The origin of the fastest star in our galaxy revealed The fastest known star in the Milky Way is on its way out of the galaxy, and the latest research shows that a supernova gave the star a galactic kick. The refugee star US 708 is moving at a speed of 12,000 km/s - or 43 million km/h - and is thus identified as the fastest star in the Milky Way known to astronomers to date. Its speed allows it to escape the gravitational pull of the galaxy and ultimately escape into intergalactic space. Most other stars that move fast enough to escape the galaxy are believed to be thrown out by the monstrous black hole at the galaxy's center. US 708 is the first star with a different origin story so far, and the study shows it had a strange and chaotic life. Our Sun and most of the millions of stars in the Milky Way collectively orbit the center of the galaxy at a relatively slow speed: our Sun moves at 724,000 km/h, or 200 km/s. But there is a class of so-called hypervelocity stars that move at high enough speeds to escape the gravitational pull of the galaxy. Until now, the fastest of these high-speed stars was moving at a speed of about 3.5 million kilometers per hour. But US 708 is traveling at more than 40 million kilometers per hour. “It's significantly faster,” says Stefan Geyer, a research fellow at the European Southern Observatory and co-author of the new study. Geyer and his colleagues first discovered US 708 in 2005. In his new work, together with colleagues, he was able to measure the speed of the star using current and historical data, and track the change in its movement over a total of 70 years. The supermassive black hole at the center of the Milky Way can flex its gravitational muscles and eject any star that happens to be in its neighborhood, and many other high-velocity stars are believed to have come from there. But US 708 did not begin its movement from the galactic center. Scientists say the star was likely in orbit of another star when its path changed. US 708 and its partner were orbiting each other very quickly and with very little space between them. A nearby star exploded as a supernova and was completely destroyed. US 708 suddenly found itself without a gravitational tether, and the speed of rotation suddenly gave the star motion in a straight line. “It's like you're riding on a carousel connected to a chain, and if you cut the chain, you'll immediately fly off the carousel,” Geyer says. “In this case, the carousel exploded.” Scientists cannot look back in time and see what happened to US 708 before it took its current course. But the clues they need are hidden in the physical characteristics and current behavior of the star. Speed isn't the only thing that sets US 708 apart from other high-speed stars. Until 2014, all discovered stars of this type were similar to our Sun. Earlier that year, a group of larger high-velocity stars was discovered (these stars appear to have been born in the center of the galaxy). But US 708 is not average, large or huge; it is known as a hot subdwarf. As their name suggests, hot subdwarfs are small but very hot, suggesting they were once significantly more massive. US 708 currently has about half the mass of our Sun, but scientists say the star was most likely a red giant with two to three times the mass of our Sun. The red giant's outer hydrogen layers likely flowed into the nearby star, leaving the subdwarf mostly helium. The cannibal star was most likely a white dwarf: a collapsed star that was no longer burning fuel. After it ate the outer layers of US 708's hydrogen, it began sucking out helium, which caused the rupture. Helium is a highly flammable gas, and as the white dwarf consumed the material, creating a thick, hot layer on its surface, the helium ignited. The theory suggests that this ignition and accumulation of helium led to the combustion of carbon within the star, which could then lead to the destruction of the entire star, as in a Type 1a supernova explosion. “The white dwarf was completely destroyed,” Geyer says. Again, the separatio yt3.ggpht.co

Can astronomy explain the Star of Bethlehem? Bright stars adorn the tops of Christmas trees around the world. Almost everyone knows about the star that led the wise men to the manger in the small town of Bethlehem, where Jesus was born. The Star of Bethlehem is described in the Gospel of Matthew in the New Testament. Is this star a biblical fiction or did it really exist? Let's look at it from the astronomers' point of view, described on Phys.org. To understand the Star of Bethlehem, we need to think like the Three Wise Men thought. Guided by this “star in the east,” they first arrived in Jerusalem and informed King Herod of the prophecy: a new ruler of the people of Israel had been born. We also need to think like King Herod, who asked the three wise men when the star appeared, because he and his court apparently did not see the star in the sky. These events give us the first astronomical mystery of the first Christmas: how could the court wise men of King Herod not know about the appearance of such a bright star and how it led the wise men to Jerusalem? Then, to reach Bethlehem, the Magi had to go directly south from Jerusalem; "the star in the east" "moved before them until it stood over the place where the child was." And here we have the second astronomical mystery of the first Christmas: how could a star “in the east” lead the Magi to the south? The north star led lost wanderers to the north, so why didn't the star in the east lead the wise men to the east? There is a third part of the mystery of the first Christmas: how did the star described by Matthew move “before them” and then stop and hang over the manger in Bethlehem in which the baby Jesus supposedly lay? What could the “star in the east” be? Any astronomer knows that no star is capable of this. Neither a comet, nor Jupiter, nor a supernova, nor a parade of planets, nor anything else can behave like this in the night sky. One could assume that Matthew's words describe a miracle that lies beyond the laws of physics. But Matthew chose his words carefully and wrote “a star in the east” twice, suggesting that these words had special meaning for the readers of his Gospel. Can we find another explanation that fits Matthew's words and that doesn't require breaking the laws of physics? Which one will fit into the modern way of astronomy? Surprisingly, the answer is yes. Astronomer Michael Molnar points out that "in the east" is a literal translation of the Greek phrase en te anatole, which was a technical term used in Greek mathematical astrology 2,000 years ago. He describes, and very specifically, a planet that rises above the eastern horizon shortly before sunrise. Moments after the planet appears, it disappears into the bright light of the Sun in the morning sky. It turns out that no one sees this “star in the east” unless they look at it at a certain moment. Now let's bring in a little astronomy. During human life, almost all stars remain in their places. The stars come on and off every night, but do not move relative to each other. The stars of Ursa Major appear in the same place year after year. But the planets, the Sun and the Moon are different from the fixed stars; in fact, the word “planet” comes from the Greek name for “wandering star.” Although the planets, the Sun and the Moon move along approximately the same path against the stars, they move at different speeds, so they sometimes obscure each other. When the Sun covers a planet, we cannot see it, but when the Sun overtakes the planet, it appears again. Now let's turn again to astrology. When a planet reappears in the morning sky shortly before sunrise for the first time in the many months it has been hidden in the sun's glare, the moment is known to astrologers as a heliacal rising. A heliacal rising is the special first appearance of a planet, and is what Greek astrologers called en te anatole. In particular, the heliacal rising of Jupiter was considered by Greek astrologers to be an important event for all those born on this day. Thus, "star in the east" refers to an astrono yt3.ggpht.