Orion Nebula

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The Orion Nebula, also known as Messier 42, is one of the most beautiful images of the sky. It is located south of the Orion belt.

Orion Nebula a a beautiful image in the sky

It is one of the brightest nebulae in existence, and can be seen with the naked eye, against the night sky.

The Orion Nebula is one of the most photographed, examined, and researched astronomical objects.

Click here to see a wondeful video  produced by the California Institute of Technology, Department of Education and the Spitzer Space Telescope, with new infrared images of the Orion Nebula, located in the area of ​​”the sword of Orion“. Thousands of rising stars are shown.

Where is the Orion Nebula?

The Orion Nebula is one of the few nebulae that can be seen with the naked eye, even in places with some light pollution.

It is the luminous point located in the center of the region of the three stars, located south of the Orion belt.

The Orion Nebula
Orion constellation. Credit: web “astrofisicayfisica.com”

To the naked eye, the nebula appears blurry, but with simple telescopes, or simply binoculars, the nebula is seen quite clearly.

Observers have noted that the nebula has greenish areas, in addition to some red regions and others bluish with violet tints.

Who discovered the Orion Nebula?

It is quite possible that ancient Chaldean, Mayan, Greek, and Egyptian astronomers were amazed to see something like a tiny cloud in the constellation Orion.

Charles Messier became aware of its existence on March 4, 1769, while observing three of the stars that are in that area of ​​the constellation Orion.

Orion Nebula
A drawing of the Orion nebula made by Messier in 1771, published in his work “Mémoires de l’Académie Royale”. Credit: Wikipedia

The Orion Nebula was designated in his catalog as M42, as it was the 42nd object on the list to be discovered.

In 1865, spectroscopy by William Huggins confirmed the gaseous character of the nebula.

On September 30, 1880, the first astrophotography of the Orion nebula was published.

And, a little later, a second photograph better than the first, with 137 minutes of exposure, and both obtained by the astronomer Henry Draper.

What is the Orion Nebula?

The Orion Nebula is part of a huge cloud of gas and dust, called the Orion cloud, seen in the center of the constellation Orion.

It is located 1,350 light years from Earth, and extends for a diameter of approximately 24 light years.

Inside the entire nebula, new stars are formed that give off a large amount of thermal energy; and therefore, the predominant spectrum is infrared.

Astronomers have observed protoplanetary disks and brown dwarfs in its entrails.

Strong turbulence has also been detected reaching speeds of 700,000 kilometers per hour.

Trapezoid Cluster

The Orion Nebula contains a recently formed star cluster, called the “Trapezium Cluster“, due to its four main stars.

In times of good viewing conditions, all four stars can be observed with a 5-inch (127 mm aperture) amateur telescope.

It is estimated that the “Trapezoid Cluster” is made up of some 2,000 very young stars, and that it extends for a distance of 20 light years.

The Orion Nebula
Trapezium cluster optical and infrared comparison. The “Trapezium cluster” in visible light (left) and infrared (right). Credit: Wikipedia.

The “Trapezium Cluster” is located in the center of the Orion Nebula.

In addition to brown dwarfs and other stars, stellar disks have been found that can support the probable hypothesis that there are planetary formations.

Hubble Space Telescope

In 1993, the Hubble Space Telescope first observed the Orion Nebula.

Since then, the nebula has been studied and examined in depth on many occasions, and the images obtained have been used to make a detailed model of the nebula in three dimensions.

The Hubble and Spitzer space telescopes are a gem for science. Thanks to the instruments they carry, they have shown us the universe like never before, with a majesty and clarity unknown until now.

Thanks to the combination of the images from both telescopes, NASA astronomers and image and data visualization specialists have generated this fabulous recreation of what would be a trip inside a nebula, that of Orion Messier 42, as it is commonly known.

The Orion Nebula
Panoramic view of the Orion Nebula. Image taken by the Hubble Space Telescope in 2006. Credit: National Geographic.

To obtain the image, the telescope had to complete 104 orbits, and capture about 3,000 stars below the 23rd magnitude, including several brown dwarfs and possible binary brown dwarfs.

The first binary brown dwarf

A year later, a team of scientists from the Hubble Space Telescope announced the first binary brown dwarf.

This binary system of brown dwarfs is found in the Orion nebula and has approximately masses of 0.054 solar masses and 0.034 solar masses respectively, with an orbital period of 9.8 days.

Surprisingly, the more massive brown dwarf of the two is also the less luminous.

Structure of the Orion Nebula

Optical images reveal clouds of gas and dust in the Orion Nebula.

Orion nebula infrared
The Orion Nebula in Visible and Infrared. Credit:  NASA, Spitzer Space Telescope; Visible: Oliver Czernetz, Siding Spring Obs.

The huge field of view of the new telescope allows the entire nebula and its surroundings to be captured in a single image.

Its infrared vision also allows a deep look at the hidden dust regions, revealing curious emissions from the very active young stars located there.

The Orion Nebula spans a 10º region in the sky, and contains interstellar clouds, star clusters, H II regions, and reflection nebulae.

The nebula forms an almost spherical cloud, where the maximum density is reached near the center point.

The maximum temperature is 10,000º K, but near the outer edge the temperature drops drastically.

Unlike the density distribution, the cloud has very different speeds and turbulence throughout its entire extension, especially around the central region.

Relative movements within the cloud reach speeds of 10 km / s, while local variations can exceed 50 km / s.

Star formation in the Orion Nebula

The Orion Nebula is the closest stellar nursery to Earth and helps scientists explore how stars form.

A veil of gas and dust makes this nebula extremely beautiful, but it also envelops the entire star birth process.

Fortunately, infrared light can pass through this cloudy veil, allowing specialized observatories like SOFIA to reveal many of the secrets of star formation that would otherwise remain hidden.

The Orion Nebula is an example of a stellar incubator, where cosmic dust forms stars as they associate, due to gravitational pull.

Stars form when hydrogen and other elements accumulate in a region of space, where they contract due to their own gravity.

As the gas collapses, the central cluster attracts more and more particles as the mass increases.

Finally, the gas is heated to a temperature sufficient to convert gravitational potential energy into thermal energy.

If the temperature continues to rise, a process of nuclear fusion begins, giving rise to a protostar.

A protostar is said to be born when it begins to emit enough radioactive energy to compensate for its gravity and slow down gravitational collapse.

Normally, when the star begins nuclear fusion the cloud of material is at a considerable distance.

This cloud that surrounds the star is the protoplanetary disk of the protostar, from which planets can form.

Once the protostar enters the main sequence, it is classified as a star.

Orion Nebula
The stellar wind in the Orion Nebula. Credit: NASA / SOFIA / Pabst et Al.

Stellar wind from a newborn star in the Orion Nebula prevents new stars from forming nearby, according to new research using NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA).

These results were published in the January 7, 2019, issue of the journal Nature.

But SOFIA’s observations suggest that child stars generate stellar winds, that can remove the seed material needed to form new stars, a process called “feedback.”

At the heart of the nebula is a small group of young, massive and luminous stars.

The wind is responsible for bursting a huge bubble around the central stars, and disrupts the natal cloud and prevents the birth of new stars.