The Magellanic Clouds are divided up into two types: the Large Magellanic Cloud or LMC and the Small Magellanic Cloud or the SMC.
This is a pair of unusually shaped galaxies that scientists assume have happened due to their interaction with each other.
The LMC and SMC orbit around each other every 900 million years and complete an orbit around the Milky Way around every 1.5 billion years. They are located almost 200,000 light-years away from Earth.
The shape of the LMC was once thought to be irregular until astronomers had more powerful telescopes to get a closer look for study.
They discovered that the LMC is actually an irregular galaxy with a bar across the center. It’s thought that it might at one time have been a spiral galaxy.
It is known that both the SMC and LMC have areas known as star-forming regions, with the LMC having had a supernova explosion of 1987a.
The Milky Way galaxy is consuming gas from both the LMC and SMC in what is called the Magellanic Stream.
Astronomers theorize that both the LMC and SMC may collide with the Milky Way galaxy in the future. It’s the LMC that attracts a lot more attention because it is packed with the star nurseries, and this causes the area to have a bright glow.
Large Magellanic Cloud Statistics:
Galaxy Type: Disrupted Barred Spiral
Diameter: 14,000 light-years
Mass: 10 billion M☉
Constellation: Dorado & Mensa
Group: Local Group
Number of Stars: 30 billion
Distance to Galactic Center: 163,000 light-years
Small Magellanic Cloud Statistics:
Galaxy Type: Dwarf Galaxy
Diameter: 7,000 light-years
Mass: 6.5 billion M☉
Constellation: Tucana & Hydrus
Group: Local Group
Number of Stars: 3 billion
Distance to Galactic Center: 197,000 light-years
Large Magellanic Cloud
The LMC or Large Magellanic Cloud is considered to be one of the Milky Way’s dwarf satellite galaxies. At 163,000 light-years away, it’s one of the galaxies that is fairly close to Earth.
When viewed from Earth it has an appearance across the skies of the Southern Hemisphere that look something like a very faint cloud. The LMC exists on the Dorado and Mensa border.
The LMC is just one of the many galaxies that make up the Local Group. These carry the name because they are those galaxies that are the closest to the Milky Way galaxy.
The most notable in the Local Group is the Andromeda galaxy. It is 2.5 million light-years away and it is moving closer and closer to the Milky Way so that it’s assumed that it will eventually collide with the Milky Way.
The Small Magellanic Clooud:
The SMC is the fourth-closest neighbor to our Milky Way galaxy and it is around 200,000 light-years from us.
It is the partner galaxy to the LMC and both are part of the Local Group of neighboring galaxies that are near the Milky Way.
If you view the SMC, you will see that it spans out to around 7,000 light-years across.
Looking at it from Earth you will note that the SMC would take up around the same amount of room across the sky as 9-10 moons.
The SMC is considered to be relatively small for a galaxy, even though it is home to a few hundred million stars.
Even though many astronomers in the Southern Hemisphere saw the LMC and SMC for thousands of years, both the Large and Small Magellanic Clouds are named after Ferdinand Magellan, the famous explorer.
Magellan made a voyage around the world in 1519 and both he and his crew were the first to bring so much information to the Western world about other cultures and peoples.
Although Magellan died during the voyage, his crew offered documentation that showed that Magellan had identified the Magellanic Clouds during their voyage.
Up until the sophisticated telescopes were designed, astronomers knew very little about the LMC and SMC.
Both the Hubble Space Telescope and NASA’s WISE (Wide-field Infrared Survey Explorer) have given us a more in-depth view of these two galaxy neighbors.
Hubble combined it’s technologies with the sun-orbiting satellite Gaia to show LMC’s rotation as well the millions of faint stars that are at the top of the central bar.
WISE has captured images of the Small Magellanic Cloud which is around 200,000 light-years away.
The images were able to show the irregular shape of SMC and viewing with different infrared light displays the cyan and blue colors that represent stars and the red and green colors that are made up of warm dust.
Using over 3,900 frames, an image has been created that displays light that is emitted by hydrogen, sulfur, and oxygen atoms.
The image depicts LMC as it is encircled by ionized gas that surrounds the large number of young stars.
The winds are shaped due to strong stellar winds and they emit a glow that shows the hydrogen, called H II (ionized hydrogen) as a large section in the star forming area.
- The SMC is so close to the Milky Way galaxy that scientists are using it to study the type of activity that is occurring outside of the Milky Way. Astronomers grapple with the challenge of looking into a neighboring galaxy to see how stars are formed and evolve. Stars are typically covered with interstellar gas and debris. The clouds have small grains that can absorb and scatter star light, and that distorts the object’s view.
- LMC is known as a hotspot for the birth of new stars. NASA has several observatories to watch LMC and they, as well as other space agencies, report an incredible quantity of gas that comes together in the LMC star nurseries.
- Using images from Chandra, Hubble, and Spitzer space telescopes, a composite image was created of the Tarantula Nebula inside the LMC that is also known as 30 Doradus. It revealed that the center were thousands of massive stars that were causing radiation and violence as they blew off material and produced intense radiation from the strong winds.
- The Hubble Space Telescope found a star-forming area in LMC that is smaller. The area is known as LHA 120-N 11 and the images depict quite a few pockets of gas and a lot of new, bright stars.
- For astronomers, there doesn’t seem to be a better place to watch stars being born than the LMC. It is positioned correctly so that it isn’t outshone by nearby stars and it also isn’t obscured by the Milky Way’s center dust.
- Scientists are studying the rotation of the LMC as part of the explanation of how galaxies behave. They have discovered that the LMC rotation is every 250 million years.
- The researchers are planning to change their attention focus to the SMC for the same kind of rotation analysis that’s been done on the LMC. Their intent is to study how the two interact with each other and possibly effect the relationship of galaxy movements in the Local Group that they and the Milky Way belong to.
- Until new information was received, scientists always assumed that the LMC and SMC both made multiple trips around the Milky Way galaxy together. However, they now feel that the Milky Way’s gravitation pull created the “Magellanic Stream” of dust and gas that was pulled from the SMC and that the cloud pair are making their first orbit around the Milky Way galaxy.
Exploration and Research:
Henrietta Leavitt, a Harvard College Observatory astronomer, studied SMC Cepheid variables, a class of changing stars, to discover the relationship between the duration of flare and the brightness of the Cepheids.
This research has had a continuing role in figuring out the distances to objects in the visible universe.
2007: The Hubble Space Telescope confirmed that the LMC and SMC were making their first orbit around the Milky Way galaxy. The research group involved was astronomer Nitya Kallivayalil and colleagues from the University of Virginia. The group made an accurate 3D calculation of the velocities of both SMC and LMC.
2007: University of Arizona researcher, Gurtina Besla was studying dwarf galaxies when she theorized that the LMC and SMC were making their first orbit around the Milky Way galaxy. Belsa made use of the ESA’s (European Space Agency) data from the spacecraft Gaia to gauge smaller satellites that were orbiting LMC.
Astronomers made use of the VLT (Very Large Telescope) in Chile at the ESO (European Southern Observatory) for the isolation of a low-energy, magnetic neutron star that was outside of the Milky Way galaxy.
The research showed that the star was at the center of a slowly expanding gas ring that was in other rings of dust and gas that were remnants from an SMC supernova that had exploded.
Using Australia’s Murchison Widefield Array radio telescope, astronomers were able to map the SMC cosmic rays and those from the LMC.
These rays are the charged particles that are given off after a supernova explodes and then has magnetic field interaction that creates radiation that is visible by radio telescopes.
Being able to identify these rays lets astronomers figure out an approximate number of new stars that are forming.
Published in the 2018 publication of The Astrophysical Journal Letters, Sally Oey, a University of Michigan astronomer and her team of colleagues, discovered that SMC is slowly splitting apart.
The research also brought new information about the formation of stars. They used data from the ESA (European Space Agency) space telescope, Gaia, for the tracking of new stars in the SMC.
Using the ASKAP (Australian SKA Pathfinder) radio telescope array, researchers have been able to focus in on the future destruction of the SMC.
The group has been tracking the slow demise of the cloud by observing the outflow of the hydrogen gas from the SMC.
The loss of all of the gas means that no new stars can be made and those galaxies simply fade away.
Facts about Magellanic Clouds for Kids :
- In the past, scientists thought that the Magellanic Clouds orbited the Milky Way galaxy, however, recent measurements have shown that the clouds are moving at too fast of a speed to have completed any orbit.
- The Large Magellanic Cloud is around 160,000 light-years from our Earth and the smaller partner, the Small Magellanic Cloud is around 197,000 light-years away from Earth.
- The shapes of both the LMC and SMC are distorted by the interaction and gravitational pull by the Milky Way galaxy. Both are moving closer to the Milky Way and its believed that as they move closer, the gravitational pull will also cause the outer bars of our Milky Way galaxy to become misshapen.
- The Magellanic Clouds have a larger portion of their mass made up of gas and a smaller part of their mass bound in elements that are metallic. This is referred to as being “gas-rich.”
- Some of the studies of the Small Magellanic Cloud has resulted in the theory that the cloud may have once been a single galaxy that was split into two pieces. It’s thought that the LMC gravitational pull might have been responsible for the breakup.
- A highly active region of the Large Magellanic Cloud where there are a lot of new stars being born is called the Tarantula Nebula. This area is part of a bigger cloud of dust and gas. The increased number of stars that are made within the area might be caused due to interstellar dust and gas compression that was due to the cloud’s collision with an external medium. Researchers are looking at the supernova 1987a because its explosion wasn’t that far from the nebula.