synonymMagellan Cloud(The two companion galaxies of the Milky Way) generally refers to the Magellanic galaxy
Magellanic clouds areGalaxyTwo ofCompanion galaxy。Rising in the area south of 20 ° north latitudeGround level。They are two cloud like objects clearly visible to the naked eye near the Southern Milky Way.The big oneSwordfishandMountain bench, about 6 ° in size, equivalent to 12 moonsApparent diameter；The smaller oneRhododendron, opening angle is about 2 °, equivalent to 4 lunar apparent diameters;The two clouds are about 20 ° apart on the celestial sphere.
In the southern hemisphere night skyMagellanic nebulaIt is one of the most spectacular sights among the bright stars, and it is also the object that astronomers have been chasing - these are two nebulae very close to the Milky Way,Large Magellanic CloudIt is about 160000 light years away from the Earth, and the Little Magellanic Cloud is about 200000 light years away from the Earth. It is one of the closest neighbors to the Milky Way Galaxy and also the southern hemisphereNaked eyeOne of the most distant objects that can be seen.
Large (LMC, lower cloud cluster) Small (SMC, upper left)
Arabs in the 10th century and Arabs in the 15th centuryPortugalWhen people travel far south of the equator, they have noticed these two cloud like objects in the southern sky, called "Cape of Good Hope Cloud".Portuguese navigatorMagellanThey were first described precisely in 1521 when they sailed around the world, and later named after him.Da Yun shoutsLarge Magellanic Cloud, short forBarley cloud（LMC）；Xiao Yun callsMagellanic nebula, short forWheat cloud（SMC）；Collectively known as Magellanic Cloud.
In 1912, American astronomerLeavitt Found the Cepheid variable star of the wheat cloudPeripheral light relationHerzpoon and Shapley then measured the distance of wheat cloud, becoming the first confirmedExtragalactic galaxy。The distance between the barley cloud and the wheat cloud is 160000 light years and 190000 light years respectively. They are 50000 light years apart in space.Large and small wheat clouds are among the nearest galaxies, which enables us to analyze theirMember celestial body, so they are importantAstronomical observationObject, alsoGalactic astrophysicsAn important source of information.
Large Magellanic CloudAbout 180000 light years away from us,Magellanic nebulaIt is 210000 light-years away from us, and the bright star at the lower left isShip baseαElderly Star, YesGalaxyOur residents are only 310 light years away.Both big and small wheat clouds are in the south half sky distanceSouthern Celestial PoleAbout 20 °.Barley cloudbe locatedSwordfishAndMountain benchThe junction of the two constellations spans the two constellations and occupies an 8 ° × 7 ° sky area, equivalent to more than 200 full moonsApparent area。Wheat cloudbe locatedRhododendron, occupying 4 °× 2 ° of the sky, which is equivalent to the apparent area of 30 full moons.The distance between barley cloud and wheat cloud is about 20 °.In the Southern HemisphereLook bigWheat clouds, all the year round, hang high near the southern sky zenith, competing for radiance, never fallinghorizonfollowing.Like we wereNorthern HemisphereseeBig DipperNever fall below the horizon.They are a pair of treasures in the southern sky.Unfortunately, they cannot be seen in most parts of the Northern HemisphereNansha IslandsThey can only be found in places very close to the southern horizon.
The Magellan Nebula is a smallIrregular galaxy, YesGalaxyOfSatellite galaxyEvery 1.5 billion years.Because it has no standard fixed shape, the Magellanic Cloud has becomesouthern hemisphereThe most controversial celestial body, even the one that can stimulate people's imagination.Some astronomers said that the Magellan Nebula seems to bedark substanceInteractionGalaxybend.
What is the curvature of galaxies?I think this is more difficult to explain. To put it simply, the movement of neighboring nebulae may have an impact on our living Milky Way, just like the agitation at the other end of the carpet, which can cause the shape distortion like wavesSilver plateIt has become a bowl.The most famous celestial body in the Southern Hemisphere, except for the gorgeousroseOfKeyhole Nebula , ShiningSouthern CrossIn addition, it belongs toMagellanic galaxy。These two celestial bodies are invisible at the latitude of mainland ChinaGalaxy”OfSatellite galaxy, andAndromeda Galaxy （M31）Next toM32Like NGC205, it is a small galaxy beside a large galaxy.LMC is 160000 light years away from the earth, and SMC is 190000 light years away from the earth.German amateur astronomy friends cameAustraliaWhen watching the stars, I mistook LMC and SMC for two "clouds" in the sky. Why can't the wind blow away?It was a joke.NGC104 star next to SMC is another good target for viewing, and the star next to LMCtarantula nebula You can't miss it.
Like our Milky Way, the Magellanic Cloud also includes gas and stars.Barley dwarfBarred spiral galaxyorIrregular galaxy, quality isGalaxy1/20 of.Wheat cloudIrregular galaxy or irregular bar spiralDwarf galaxyThe mass is only 1/100 of that of the Milky Way.MagellanicGas contentRichness;The neutral hydrogen mass accounts forTotal mass9% and 32% are much larger than those of the Milky Way.This indicates that their evolution degree is not as high as that of the Milky Way.TheirInterstellar dustContent ratioFew in the Milky Way, but youngStar Family IThere are many objects with high luminosity O-B-type star；In addition, novaeSupernova remnant、X-ray binaryEtc.As found on February 23, 1987Large Magellanic CloudOne in the middleSupernova（SN 1987A）Its maximum brightness is 250 million times that of the sun, and it is considered to be the brightest supernova in 383 years.The Magellanic Cloud orbits the Milky Way Galaxy once every 1.5 billion years.Every time it gets closer to the Milky Way, its stars and gases will change under the influence of the Milky Way's gravity.SmallMagellanThe cloud has been torn, and its star will becomeGalaxyPart of.Big Magellanic Cloud will also be this fate in the end.
Magellan andMagellanic nebulaThey are the two nearest neighbors to the Milky Way.For hundreds of years, these two nebulae have been considered to belong to the Milky WayCompanion galaxy。howeverHarvardCelestial bodies ofphysical scientistThe latest research by Gurtina Besla and his colleagues shows that the Magellanic Cloud is a recent arrival and the first visitor to the Milky Way.
These two nebulae are not only irregular in appearance, but also likeVolcanic cloud。amongLarge Magellanic Cloud160000 light years from the Earth, about 1/20 of the diameter of the Milky Way;Magellanic nebula200000 light years from the earth, onlyGalaxyOne hundredth of.
Many years ago, astronauts claimed that the Magellan Nebula traversed the three dimensions of the Milky WayVelocity fieldIt is much larger than before. There are two explanations for this phenomenon: (1) the Milky Way is much larger than the one that passed through before; (2) the Magellanic Cloud is not affected by the Milky Wayfield of gravityConstraints.But further research by Besla and his colleagues confirmed the second view, and they claimed that the Magellanic Cloud was the first time that it passed through the Milky Way.
However, such observations are still under consideration.Because if we take the Milky Way as the reference plane, the warping depth can reach 10000 light-years.But these two nebulae only came once 1 or 3 billion years ago, so their gravitational tides are unlikely to cause such warping.Faced with such a situation, Besla said: "We still have many unsolved mysteries. When an answer appears, there may be more questions."
