When studying the spiral arms of the Milky Way, optical methods are very limited.The knowledge about the spiral arms of the Milky Way is mainly derived from radio observations.Near the sun, radio observations detected three segments of spiral arms, namelyPerseusSwivel armOrion arm And Sagittarius Swivel Arm.The sun is near the inside of the Orion spiral arm.In the 1970s, people explored the Milky Waycarbon monoxideThe distribution of molecules has found a fourth spiral arm, which spansFoxyandCygnus。It is a stripSilver corefour thousandSecond gapThe swivel arm of is called3000 second gap arm, expanding outward at a speed of about 50 km/s.Known: The spiral arm is the place where gas, dust and young stars are concentrated.
The Milky Way Galaxy is a flat disk with thick middle and thin edge.His main part is calledSilver plate, is aVortex structure。itsTotal massIt is about one trillion times the size of the sun, about 100000 light-years in diameter, about 10000 light-years thick in the center, and about 3000 to 4000 light-years thick at the edge.Outside the silver disk are sparse stars andInterstellar matterConstituentSpheroid, known asSilver halo, with a diameter of about 100000 light-years.A careful observation of the Milky Way shows that it has four spiral arms, namely Orion, Perseus, Sagittarius and 3000 second gap.The Milky Way also rotates.The solar system orbits at 250 km/sGalactic centerRotate for about 250 million years.The Milky Way has twoCompanion galaxy, respectivelyLarge Magellanic GalaxyandMagellanic galaxy。 Galaxies other than the Milky Way are calledExtragalactic galaxy。The sun is located about 27700 light-years away from the center of the Milky Way GalaxyOrion arm Inside.
Since 2003, the research team has measured 163High qualityStar formationIn the areaMaizeyuanIn combination with 37 maser sources measured by other groups in the world, the self motions and self motions of nearly 200 massive star forming regions in the Milky Way were obtained.The distribution of these massive star forming regions on the silver disk clearly delineates four main spiral arms, which arePerseus arm, centaur bottom armNomaArm And shield-Centaurus arm 。[2]
Observation results
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After a year of observation, an international astronomical team was lucky to "catch" one of them.Journalists fromShanghai Astronomical Observatory It is learned that the instituteXu YeThe international team participated by the doctor accurately measuredsolar systemThe distance to the nearest "arm" of the Milky Way, the "Perseus spiral arm", is 6370 light-years.[1]
Shanghai ObservatoryShen ZhiqiangThe researcher said: "In order to accurately understand the age and size of the Milky Way, we need to accurately measure the distance between these arms. But the biggest problem is that we are observing otherGalaxyTheir shapes are clear at a glance, but we can't see the full picture of our own Milky Way, so we can only determine their shapes through observation and speculation. "[1]
It is reported that this is the farthest accurate measurement of human beings so farDistance of celestial bodiesIt is of great significance to accurately describe the age and size of the universe.This achievement was also published in the latest issue of Science.
It is understood that,Galaxyyesspiral galaxy , four rotating "arms" protrude from the inside out: Sagittarius rotating armOrion arm , Perseus Swivel Arm and3000 second gap arm。Each "arm" is composed of countless stars and nebulae.Our solar system is located in the Orion spiral arm, between the Sagittarius spiral arm and the Perseus spiral arm, but closer to the Perseus spiral arm.
In May 2023, the team of Xu Ye, a researcher at the Zijinshan Observatory of the Chinese Academy of Sciences, cooperated with the National Astronomical Observatory of the Chinese Academy of Sciences, and proposed a new understanding of the shape of the spiral arms of the Milky Way: the Milky Way is more like an ordinary multi spiral arm galaxy, composed of two symmetrical spiral arms inside and several irregular spiral arms outside, rather than the widely accepted special shape of four spiral arms from inside to outside.[3]
Observation method
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It is revealed that the scientists of the three countries skillfully adopted a kind of“Trigonometric parallax”Method, usingradio telescopeWe successfully captured a cosmic laser emission source from the "Perseus Swivel Arm", and took the distance between the sun and the earth as the baseline. After geometric calculation, we got thisradiation sourceDistance.
According to the observation results of the team, the sun goes to PerseusSwivel armIs 1.95Kilosecond gap, about 6370 light years, with an error of less than 2.1%.
The Milky Way consists of four large and two small spiral arms.The solar system sits on the shorter Orion spiral arm, between the Perseus spiral arm and the Sagittarius spiral arm.The spiral arms are the cradle of new stars in the Milky Way.In fact, there are about ten new stars forming in the Milky Way every year, and at least one star aging every 100 years.Newborn stars appear on the spiral arms of the Milky Way.
January 5, 2009, United StatesIowaUniversity founded to publish newsbulletinSaid that the scientists of the university and SwitzerlandUniversity of ZurichGermanyRuhr UniversityScientists cooperated to draw a complete image of the spiral arms of the Milky Way for the first time.image displayThere are two obviously symmetrical spiral arms inside the Milky Way, which extend to the outside of the Milky Way and divide into four spiral arms.
Cause
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High speed operation in the universe hasGalactic nucleusWhen it reaches another galaxy with a galactic nucleusrunning speed If they are close, they will devour each other and form a larger galaxy.If the galactic nuclei of these two galaxies meet, they will rotate around each other to form a faster rotating galactic nucleus with greater mass. This faster rotating galactic nucleus is like a huge generator, bursting out powerful particles from its poles and flowing into the distance.The greater the energy of the galactic nucleus, the greater the flux of the jet stream, and the farther the jet will go.We call such galactic nucleiBipolar jet galactic nucleus。The galactic nucleus is ejectingHigh-energy particleWhen flowing, it will consume its own energy.However, when it captures other star clusters or galaxies, it will add energy.When the energy of the galactic nucleus changes from large to small, two massiveJet belt。If the galactic nucleusMagnetic axisAround another axis called galactic nucleusAutorotation shaft）Rotate, then the trajectory of the jet belt will bendSpiral galaxyThe two spiral arms of the Milky Way Galaxy are built in this way.
