Messier 87 is also called M87 or NGC 4486 and this is an elliptical supergiant galaxy that is called a “Virgo A” or the Smoking Gun. It’s positioned in the heart of the Virgo Cluster that is located in the southern constellation Virgo. M87 is the largest elliptical galaxy that we can see from Earth.
One of the most interesting features of M87 is the jet that is visible when using x-rays, radio emission, and even optical light. The jet sprays out from the supermassive black hole in the center of the galaxy and reaches out nearing 5,000 light-years.
M87 is considered to be a “true” elliptical galaxy but doesn’t have any dust lanes or areas for star nurseries. It’s believed that the galaxy was formed due to a merging of two other galaxies.
M87 has several trillion stars and around 15,000 globular star clusters. To give you an idea of its size, the Milky Way galaxy has only around 150 globular clusters and nearing a few hundred billion stars.
When it comes to the galactic neighborhood, M87 dominates the scene in the Virgo cluster of galaxies. This cluster has nearing 2,000 galaxies total, so it’s saying a lot when we say the M87 is the reigning king.
Messier 87 Statistics:
- Designation: M87 or NGC 4486
- Galaxy Type: Elliptical
- Diameter: 120,000 light-years
- Mass: 2,400 billion M☉
- Constellation: Virgo
- Group: Virgo Cluster
- Number of Stars: 1 trillion
- Distance to Galactic Center: 53 million light-years
Even though M87 is 53.5 million light-years away from Earth, it has an apparent magnitude of 9.59. This means that the brightness of M87 is above average and can be more easily viewed.
The galaxy that we know as M87 has been seen by countless people as a faint mist in civilizations all around the world for thousands of years. Although the people didn’t know that it was a galaxy, at one point in history scientists thought that it, along with many other misty views in the night sky, were nebula that existed inside the Milky Way galaxy.
In 1781, Charles Messier discovered M87 and included it as a nebulous feature in the sky in his catalog with the designation.
Heber Curtis of the California Lick Observatory was the first astronomer to detect M87’s giant jet and to note that M87 didn’t have a spiral structure.
Even though M87 is a giant among galaxies, to see any details, it required telescopes. Prior to 1991, the only astronomer that ever saw M87’s jet without the help of photography was Otto Struve, a Ukrainian-American astronomer at the Los Angeles Mount Wilson Observatory. Struve used the 100-inch telescope at the observatory for a view of the jet.
M87 is considered to be the most massive, the largest, and the most luminous galaxy in our local universe. Scientists have estimated that its mass is nearing 2.7 trillion solar masses. It’s mass is 200 times the mass of the Milky Way galaxy, even though the two galaxies have a similar size.
Even though it’s the most luminous or bright of galaxies, its distance only gives it an absolute magnitude of -22.
A composite image taken by the Hubble Space Telescope have shown the jet as the most striking feature. The jet is a blue color and is nearing the center of M87. The image also shows an incredible number of star-like globular clusters throughout the galaxy.
It is home to a minimum of 1 trillion stars, yet astronomers have found that there are star nurseries in only a small part of the mass of the galaxy.
Scientists use a ratio to measure the amount of light being generated from a galaxy’s stars. M87’s luminosity ratio is 6.3, which means that only one sixth of its mass is involved in star formation.
The Virgo Cluster has a larger number of elliptical galaxies in its central region and as its clusters continue to move toward the core and merge, it appears that M87 will continue to grow in size.
It’s believed that the giant elliptical galaxies form after a series of collisions and mergers that involve numerous spiral galaxies.
One of the theories about the globular cluster is that they may have accumulated due to gravity pulling on them from the dwarf galaxies that are nearby. This idea is based on the fact that the dwarf galaxies have almost no globular clusters.
Like most galaxies, M87 has a black hole and in this case, the jet is powered by the black hole. This happens as material is being ejected from the core of M87.
Gaseous material that is located in the galaxy’s center enters the black hole and then there is a release of energy that creates a stream of subatomic particles. The particles accelerate in speeds that are almost the speed of light.
In images taken of the M87 jet it has a brightness that is higher due to the speed traveling in the direction of Earth. However, the true trajectory of the jet is just a bit offset from Earth’s line of sight of M87, so we see a little of the jet length.
The shockwave of the jet is nearing the point where the jet seems to curve downward. This notates the areas where the particles that are moving fast collide with the galaxy’s gas and begin to slow down.
NASA’s Spitzer Space Telescope has taken another image that shows that M87 has a second jet. It’s moving away from our view at such a speed that it is almost invisible on every wavelength and creates a shockwave that appears like an inverted letter “C.” The Spitzer telescope’s images show M87 as a hazy, blue puff in space.
The supermassive black hole at the center of M87 is around 6.5 billion times the mass of our sun.
The Event Horizon Telescope along with eight ground-based radio telescopes around the globe took a more recent image close-up that shows the black hole’s silhouette. They operated as if they were one giant telescope that was the size of Earth.
Additional in-depth photographs have shown that Virgo A goes out beyond 120,000 light-years and that it has outer regions that aren’t circular like many, but instead are elongated. Taking the calculations, the size corresponds to over 1 million light-years in special extension.
The distortion of the outer regions of M87 are thought to be due to encounters with other galaxies, allowing M87 to absorb the materials.
Hubble Space Telescope observations have also shown that the M87 gas clouds have what is called “superluminal motion.” This is thought to be an illusion that is cause due to the jet stream pointing in the Earth’s direction.
Discovering this illusion assisted in supporting a theory that radio galaxies, quasars, and BL Lacertae objects may all be galaxies that are viewed from different perspectives.
Analysis of the nuclear region spectrum has shown lines of emissions that include a variety of ions including: hydrogen, helium, oxygen, nitrogen, magnesium, and sulfur.
They have found that the lines for weakly ionized atoms are stronger than the strongly ionized atoms and M87 is therefore referred to as “low-ionization nuclear emission-line.” The mechanism that causes this is still being debated by scientists.
- While almost all galaxies have a supermassive black hole at their center, astronomers think that M87 may have more than one of these black holes at its core.
- M87’s supermassive black hold is a strong multi-wavelength radiation source, specifically radio waves. There is an interstellar medium of gas between its stars that is chemically enriched from the elements emitted by stars that have already evolved.
- The diameter of M87 is bigger than Pluto’s complete orbit.
- The jet spewing out of M87 is energetic plasma that originates at the core and then expands out to around 4,900 light-years.
- There is a collection of galaxies near M87 that are arranged in a pair of chain-like structures. These are called Markarian’s Chain and can be seen by observers with a good-sized telescope.
- The dust in the M87 galaxy is surrounded by a hot gas corona and is a lot less than the amount in the Milky Way galaxy.
- M87 isn’t a flat spiral, but instead shaped like a sphere.
- M87 is growing. Scientists are using very large telescopes to watch the supergiant elliptical galaxy get bigger. They have confirmed that its growth is due to absorbing of interstellar matter gained from eating the smaller galaxies near it.
- As scientists continue to watch and study M87 they have found that in the last one billion years, it’s merging with a smaller galaxy.
- Scientists are also watching as M86 and M87 get closer to each other for their first encounter. It’s thought that in the past, M87 interacted with M84, explaining the truncated halo that M87 has.
- Another explanation of the halo structure could be due to the contraction caused by an unknown/unseen mass, such as dark matter, heading into the galaxy from somewhere in the cluster. Scientists also think that yet another reason could be feedback from M87’s active nucleus.
Exploration and Research:
NASA’s Spitzer Space Telescope took in-depth images of M87.
The EHT (Event Horizon Telescope) took images that showed the faint traces of the material being spew by the M87 jet and the shockwave that the jet created.
NASA observatories that have studied M87 include the Hubble Space Telescope, Chandra X-ray Observatory, NuSTAR, and he New Horizon Telescope.
1966: Halton Arp, an American astronomer, discovered the M87 second jet that is pointed in the opposing direction of Earth’s observations.
Facts about Messier 87 for Kids:
- The gas that fills M87 has been enriched by materials that were left over from its stars that died off a long time ago.
- Scientists are astounded at the speed that the M87 jet has as it spews material from its black hole.
- Astronomers are still trying to crunch the numbers but quite a few believe that M87 may have more than one supermassive black hole at its core.
- M87 is a galaxy that is surrounded in a hot gas corona.
- Due to its incredible brightness in all kinds of viewing, including visible, radio, x-ray and other wavelengths, M87’s nuclear area is known as an “active galactic nucleus.”
- Both the Hubble Space Telescope and the Chandra X-ray Observatory have tracked a knot of matter within the M87 jet that has been designated as HST-1. It’s about 210 light-years from the core. In a 4-year period they have noted that the intensity of the x-ray has increased by a factor of 50, but the X-ray emissions have been decaying.
- Observations of the material being ejected from the supermassive black hole shows that the rate is variable. The variations create pressure waves in M87’s hot gas and the Chandra X-ray Observatory detected rings and loops within the gas that may indicate that every few million years there are minor eruptions.
- The 1999 images taken by the Hubble Space Telescope included the M87 jet motion. The speed that was measured showed that it is 4-6 times the speed of light. This is a phenomenon that is known as superluminal motion and is believed to be an illusion due to the view of the jet.
- M87 experiences what is known as an “infall of gas” at a rate of 2-3 solar masses each year. It’s believed that most of this is moved to the core area of the galaxy.
- M87 is thought to have at least 50 satellite galaxies in its immediate neighborhood.