The
Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus.It constitutes the visible portions of the Cygnus Loop, a supernova remnant, many portions of which have acquired their own individual names and catalogue identifiers. The source supernova was a star 20 times more massive than the Sun which exploded between 10,000 and 20,000 years ago. At the time of the explosion, the supernova would have appeared brighter than Venus in the sky, and visible in the daytime. The remnants have since expanded to cover an area of the sky roughly 3 degrees in diameter. A recent determination of 2400 light-years is based on direct astrometric measurements.
In modern usage, the names
Veil Nebula,
Cirrus Nebula, and
Filamentary Nebula generally refer to all the visible structure of the remnant, or even to the entire loop itself. The structure is so large that several NGC numbers were assigned to various arcs of the nebula.=10.5px There are three main visual components:
- The Western Veil (NGC 6960): Also known as The Witch's Broom
- The Eastern Veil (NGC 6992)
- Pickering's Triangle
The nebula was discovered on 5 September 1784 by William Herschel. He described the western end of the nebula as "Extended; passes thro' 52 Cygni... near 2 degree in length", and described the eastern end as "Branching nebulosity ... The following part divides into several streams uniting again towards the south."
The Veil Nebula is expanding at a velocity of about 1.5 million kilometers per hour. Using images taken by the Hubble Space Telescope between 1997 and 2015, the expansion of the Veil Nebula has been directly observed.
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