Orion Nebula - History

History

There has been speculation that the Mayans of Central America may have described the nebula within their "Three Hearthstones" creation myth; if so, the three would correspond to two stars at the base of Orion, Rigel and Saiph, and another, Alnitak at the tip of the "belt" of the imagined hunter, the vertices of a nearly perfect triangle with Orion's Sword (including the Orion Nebula) in the middle seen as the smudge of smoke from copal incense in a modern myth, or, in (the translation it suggests of) an ancient one, the literal or figurative embers of a fiery creation.

Neither Ptolemy's Almagest nor Al Sufi's Book of Fixed Stars noted this nebula, even though they both listed patches of nebulosity elsewhere in the night sky; nor did Galileo mention it, even though he also made telescopic observations surrounding it in 1610 and 1617. This has led to some speculation that a flare-up of the illuminating stars may have increased the brightness of the nebula.

The first discovery of the diffuse nebulous nature of the Orion Nebula is generally credited to French astronomer Nicolas-Claude Fabri de Peiresc, on 26 November 1610 when he made a record of observing it with a refracting telescope purchased by his patron Guillaume du Vair.

The first published observation of the nebula was by the Jesuit mathematician and astronomer Johann Baptist Cysat of Lucerne in his 1619 monograph on the comets (describing observations of the nebula that may date back to 1611). He made comparisons between it and a bright comet seen in 1618 and described how the nebula appeared through his telescope as:

"one sees how in like manner some stars are compressed into a very narrow space and how round about and between the stars a white light like that of a white cloud is poured out"

His description of the center stars as different from a comets head in that they were a "rectangle" may have been an early description of the Trapezium Cluster (The first detection of three of the four stars of this cluster is credited to Galileo Galilei in a February 4, 1617 although he did not notice the surrounding nebula — possibly due to the narrow field of vision of his early telescope.)

The nebula was independently discovered by several other prominent astronomers in the following years, including, in 1656, Christiaan Huygens (whose sketch was the first published, in 1659).

Charles Messier first noted the nebula on March 4, 1769, and he also noted three of the stars in Trapezium. Charles Messier published the first edition of his catalog of deep sky objects in 1774 (completed in 1771). As the Orion Nebula was the 42nd object in his list, it became identified as M42.

In 1865 English amateur astronomer William Huggins used his visual spectroscopy method to examine the nebula showing it, like other nebula he had examined, was made up of "luminous gas". On September 30, 1880 Henry Draper used the new dry plate photographic process with an 11-inch (28 cm) refracting telescope to make a 51-minute exposure of the Orion Nebula, the first instance of astrophotography of a nebula in history. Another set of photographs of the nebula in 1883 saw breakthrough in astronomical photography when amateur astronomer Andrew Ainslie Common used the dry plate process to record several images in exposures up to 60 minutes with a 36-inch (91 cm) reflecting telescope that he constructed in the backyard of his home in Ealing, outside London. These images for the first time showed stars and nebula detail too faint to be seen by the human eye.

In 1902, Vogel and Eberhard discovered differing velocities within the nebula and by 1914 astronomers at Marseilles had used the interferometer to detect rotation and irregular motions. Campbell and Moore confirmed these results using the spectrograph, demonstrating turbulence within the nebula.

In 1931, Robert J. Trumpler noted that the fainter stars near the Trapezium formed a cluster, and he was the first to name them the Trapezium cluster. Based on their magnitudes and spectral types, he derived a distance estimate of 1,800 light years. This was three times further than the commonly accepted distance estimate of the period but was much closer to the modern value.

In 1993, the Hubble Space Telescope first observed the Orion Nebula. Since then, the nebula has been a frequent target for HST studies. The images have been used to build a detailed model of the nebula in three dimensions. Protoplanetary disks have been observed around most of the newly formed stars in the nebula, and the destructive effects of high levels of ultraviolet energy from the most massive stars have been studied.

In 2005, the Advanced Camera for Surveys instrument of the Hubble Space Telescope finished capturing the most detailed image of the nebula yet taken. The image was taken through 104 orbits of the telescope, capturing over 3,000 stars down to the 23rd magnitude, including infant brown dwarfs and possible brown dwarf binary stars. A year later, scientists working with the HST announced the first ever masses of a pair of eclipsing binary brown dwarfs, 2MASS J05352184–0546085. The pair are located in the Orion Nebula and have approximate masses of 0.054 M_☉ and 0.034 M_☉ respectively, with an orbital period of 9.8 days. Surprisingly, the more massive of the two also turned out to be the less luminous.