Rod spinningGalaxy，It means that there is a short bar shaped star cluster in the middlespiral galaxy。About two-thirdsspiral galaxyIt's a barred spiral galaxy.The short bar usually affects the stars andInterstellar gasAnd it will also affectSwivel arm。The spiral arms of barred spiral galaxies appear to emerge from the ends of short rods.In ordinary spiral galaxies, the stars are directly gushing from the core;In the galaxy taxonomy, it is represented by the symbol SB.[1]
All dayBright galaxyAmong them, barred spiral galaxies account for about 15%. When dark galaxies are counted, the proportion of barred spiral galaxies increases to 25%.In terms of mass, luminosity and spectrumMember celestial bodyOfStar family type, distribution of gas and dust,Galactic diskandGalactic haloThe structure and spatial distribution characteristics ofspiral galaxybe similar.
The motion characteristics of barred spiral galaxies are that the core is often aHigh qualityA fast rotating body of,motion state andspace structureComplex, the gas and stars inside and near the rod structure have nonCircular motion； Galactic disks seem to dominate the exterior of galaxies, accounting for a large part of the mass of galaxies.
There are many basic problems to be solved in rod spiral galaxies, such as how the rod structure is formedGalactic evolutionWhat role does it play in the process.
Classification of galaxies
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According to Hubble's classification and Wokule's classification, barred spiral galaxies can be divided into three categories: ① normal barred spiral galaxies SBa, SBb and SBc; ②Lenticular barred spiral galaxy SB0; ③Irregular barred spiral galaxies SBd and SBm.
Rod shaped rotating nebula NGC1672 photographed by the Hubble Space Telescope
Normal bar spiral galaxies are characterized by obvious bar structure,Swivel armExtending from the rod end, usually withRod body90 degrees.Swivel arm fromHypotypeA to c are becoming more and more popular.The rod like structures of SBa and SBb are smooth, while bright stars, bright nodes or bright clusters are clearly visible on the rod body and the rotating arm of SBc.
Lenticular barred spiral galaxy SB0 andElliptical galaxyThe difference between SBa and the normal barred spiral galaxy is that it has no spiral arms.Its shape is likeGreek alphabetΘ，That is, there is one in the centerBright nucleusOutside the core, there is a ring of lenticular galaxy disk with darker brightness and concentric with the core. The two ends of the bar generally intersect on the periphery of the disk.
The rod like structure of irregular barred spiral galaxies SBd and SBm is not necessarily at the center of the galaxy, and its spiral arm structureIrregularityIncrease from d to m.The luminosity of rod structure accounts for aboutGalactic luminosity10~20%;The color is often redder than the swing arm.
NASA(NASA）Recently, a bar spiral galaxy was estimated, which is about 30 million light years away from the EarthClock base(Horologium constellation).
Barred spiral galaxy
BARRED SPIRAL GALAXY is a long bar shaped galaxy with its centerSpiralFor spiral galaxy, the center of general spiral galaxy has a circular core, while the center of bar spiral galaxy has a circular core.
