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Messier 87

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Messier 87, often called M87, is a massive supergiant elliptical galaxy.

Virgo constellation map
Virgo constellation map

It is located in the constellation Virgo. This galaxy is one of the largest and most massive systems in our local universe. Unlike the flat, disk-shaped Milky Way, M87 has an ellipsoidal shape. This means it looks more like a rounded ball or an egg. It is categorized as an E0 galaxy because it shows no obvious flattening.

HubbleTuningFork
HubbleTuningFork

It is also called a cD galaxy because it has a large, diffuse envelope of stars around its nucleus. M87 is a vital subject for astronomers studying how galaxies evolve and grow.

The structure of M87 is defined by its massive scale and unique movement. It contains several trillion stars that are spread out in a nearly spherical way. These stars do not follow the orderly, circular paths seen in spiral galaxies. Instead, they move in random orbital motions. This random movement is what maintains the galaxy's elliptical shape. The density of these stars is highest at the center. The luminosity, or brightness, decreases as you move further away from the core. M87 also contains about 15,000 globular clusters. These are tight groups of stars that orbit the galaxy. This is a much larger population than the 150 to 200 clusters found in the Milky Way.

At the very center of M87 lies an active galactic nucleus. This nucleus is powered by a supermassive black hole. This black hole acts as a massive engine for the galaxy. It creates a powerful jet of energetic plasma. This jet originates at the core and extends at least 5,000 light-years into space. The jet travels at a relativistic speed. This means it moves at a speed close to the speed of light.

Close-Up Look at a Jet Near a Black Hole
Close-Up Look at a Jet Near a Black Hole

The galaxy is also a strong source of multi-wavelength radiation. It is particularly bright in radio waves. This makes it a very important target for radio telescopes across the world.

History shows how our understanding of M87 has changed over time. The French astronomer Charles Messier discovered the object in 1781. At that time, he cataloged it as a nebula. In the 1880s, John Dreyer included it in the New General Catalogue as NGC 4486. In 1918, Heber Curtis noticed the galaxy lacked a spiral structure. He also observed a straight ray connected to the nucleus. In 1922, Edwin Hubble helped redefine what M87 was. He first classified it as a globular nebula. By 1926, he distinguished extragalactic nebulae as independent star systems. He then classified M87 as an elliptical extragalactic nebula.

MC LRGB
MC LRGB

Modern technology has allowed us to measure M87 with incredible precision. We know the galaxy is approximately 55 million light-years from Earth. It is the second-brightest galaxy in the northern Virgo Cluster. Scientists have used many methods to estimate its distance. These include measuring the brightness of planetary nebulae and using red giant stars. The mass of the central black hole has been studied extensively. In 1978, models suggested a mass of five billion solar masses. Later, data from the Hubble Space Telescope suggested a mass of 2.4 billion solar masses.

Telescopes Unite in Unprecedented Observations of Famous Black Hole M87
Telescopes Unite in Unprecedented Observations of Famous Black Hole M87

In 2017, the Event Horizon Telescope (EHT) captured data to image the black hole's shadow. A processed image was released on 10 April 2019.

EHT-PRIMO-refinement
EHT-PRIMO-refinement

There are several surprising facts about the mass and composition of M87. The galaxy's diameter is about 132,000 light-years. This is about 51% larger than the diameter of the Milky Way. Within a radius of 2.4 kiloparsecs, the mass is twice that of the Milky Way. However, most of this mass is not made of stars. Only about one-sixth of the mass is in the form of stars. The rest is likely dark matter or diffuse gas. The interstellar medium consists of gas enriched by evolved stars. The galaxy also experiences an infall of gas. This happens at a rate of two to three solar masses per year. Most of this gas may be pulled into the core.

Studying M87 helps scientists understand the broader life cycles of galaxies. Elliptical galaxies are thought to form through mergers. This happens when smaller galaxies collide and join together. Observations of planetary nebulae suggest M87 absorbed a medium-sized spiral galaxy about a billion years ago.

Galactic Chromodynamics
Galactic Chromodynamics

We can also see evidence of this through tidal stripping. This is when the gravity of a large galaxy pulls stars away from a smaller one. There are even linear streams of stars to the northwest of M87. These streams may be remnants of smaller galaxies being pulled in. M87 serves as a massive laboratory for studying gravity and galactic evolution.

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🖼️ Images & Media (7)
File:HubbleTuningFork.jpg
HubbleTuningFork.jpg
File:Virgo constellation map.svg
Virgo constellation map.svg
File:Galactic Chromodynamics.jpg
Galactic Chromodynamics.jpg
File:Telescopes Unite in Unprecedented Observations of Famous Black Hole M87.jpg
Telescopes Unite in Unprecedented...
File:EHT-PRIMO-refinement.jpg
EHT-PRIMO-refinement.jpg
File:Close-Up Look at a Jet Near a Black Hole.jpg
Close-Up Look at a Jet Near a Black Hole.jpg
File:MC LRGB.jpg
MC LRGB.jpg
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