MiLky Way SubGroup WiTh SaTeLLiTe GaLaxys

SubGroup Word Descriptions In FohnehTik EengGLish Voeess Sownd Chahrz

THuh NexT TekST Wuhz Fruhm:

definitions - subgroup

subgroup (n.)

1.(mathematics) a subset (that is not empty) of a mathematical group

2.a distinct and often subordinate group within a group

Merriam Webster

Subgroup , n. (Biol.) A subdivision of a group, as of animals. Darwin.

MiLkee Waee Subgruup Pikchr:


SaTeLLiTe GaLaXy Term Description In FohnehTik EengGLish Voeess Sownd Chahrz

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What Is a Satellite Galaxy?

Our sun is part of a massive collection of stars in the Milky Way galaxy. These hundreds of billions of stars orbit the galaxy’s center. But did you know that there are things that are even bigger orbiting the Milky Way’s center? Other galaxies orbit it too!


These less massive galaxies have their own impressive collection of stars, which all orbit their own center; but the galaxies and everything in them orbit our galaxy too. It’s as if our galaxy is the sun and those other galaxies are planets. Astronomers call them “satellite galaxies.”

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The Nearest Galaxies

The Large and Small Magellanic clouds were thought to be the closest galaxies to ours, until 1994, when the Sagittarius Dwarf Elliptical Galaxy (SagDEG) was discovered. In 2003, the Canis Major Dwarf Galaxy was discovered - this is now the closest known galaxy to ours! …

The Canis Major Dwarf Galaxy

The Canis Major Dwarf Galaxy is only 25,000 light years from the Sun, and 42,000 light years from the Galactic center. It too, is well-hidden by the dust in the plane of the Milky Way - which is why it wasn't discovered until recently.

This galaxy is also being pulled apart by the Milky Way's gravity - as it orbits the Milky Way, it is leaving a long filament of stars, gas, and dust in its wake. This 200,000 light year-long filament is known as the Monoceros Ring, and actually wraps three times around our galaxy! The Canis Major Dwarf galaxy was discovered in the course of the investigation of this Ring, which was first discovered in 2002. [ BeeLoh Iz ] an illustration of the Milky Way, the Canis Major Dwarf, and the stream of material coming from the Galaxy.


Distance Information

The closest known galaxy to us is the Canis Major Dwarf Galaxy, at 236,000,000,000,000,000 km (25,000 light years) from the Sun. The Sagittarius Dwarf Elliptical Galaxy is the next closest , at 662,000,000,000,000,000 km (70,000 light years) from the Sun.

The Large Magellanic Cloud, 1,690,000,000,000,000,000 km (179,000 light years) away, was once considered the nearest galaxy outside of the Milky Way. The Small Magellanic Cloud is 1,980,000,000,000,000,000 km (210,000 light years) away.
How Do We Calculate Distances of This Magnitude?

Astronomers primarily use Cepheid and/or RR Lyrae Variables to measure distances to the LMC, the SMC, and the Dwarf Galaxies. The distance to the LMC has come to play such a crucial role in establishing the extragalactic distance scale that several research groups are applying a variety of methods other than the Cepheids and RR Lyraes. These alternative techniques, which include the use of SN 1987A, the so-called red clump stars, and eclipsing binaries are used to check the accuracy of the period-luminosity relationships. By using several different methods to determine distances, astronomers can increase the accuracy of and our confidence in the RR Lyrae and Cepheid methods, and the distances determined by them.

For more information about Cepheids and RR Lyrae, please read the section on calculating distances in the Milky Way.
Why Are These Distances Important To Astronomers?

If you measure the distance to one object in the LMC, for example, you know the distances to all the millions of objects in the LMC fairly accurately. Of course, there are not all exactly the same, but the thickness of LMC, as seen from the Earth, is much smaller than the typical uncertainties in the distances to individual objects in the Milky Way. Astronomers therefore often study LMC objects then calculate their true brightness from their apparent brightness and the latest (the most accurate) distance to the LMC. For example, astronomers have studied the supernova remnants to compare with theoretical models, or to derive a relationship between their size, energy, and brightness.
Travel Time

To get to the closest galaxy to ours, the Canis Major Dwarf, at Voyager's speed, it would take approximately 749,000,000 years to travel the distance of 25,000 light years! If we could travel at the speed of light, it would still take 25,000 years!

MiLky Way SaTeLLiTe GaLaxies Uv SuperUniverse Uv ReeL Prwvd TrwTh Saiz Ohmz.


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