Changes

| image          =

| image          =

| designation    =Various

| designation    =Various

| rightascension  =20^h 45^m 38.0^s<ref name=constellation-guide>{{cite web|url=https://www.constellation-guide.com/veil-nebula/|title=Veil nebula|accessdate=2019-12-23|publisher=constellation-guide.com}}</ref>

| rightascension  =20^h 45^m 38.0^s<ref name=constellation-guide>{{cite web|url=https://www.constellation-guide.com/veil-nebula/|title=Veil nebula|accessdate=December 23, 2019|publisher=constellation-guide.com}}</ref>

| declination    =+30° 42′ 30″<ref name=constellation-guide/>

| declination    =+30° 42′ 30″<ref name=constellation-guide/>

| distance        =1,470 ly<ref name=constellation-guide/>

| distance        =1,470 ly<ref name=constellation-guide/>

| parallax        =

| parallax        =

}}

}}

The '''Veil nebula''' is a large [[nebula]] in the [[constellation]] of [[Cygnus]].<ref name=nasa>{{cite web|url=https://www.nasa.gov/image-feature/veil-nebula-supernova-remnant|title=Veil Nebula Supernova Remnant|accessdate=2019-12-23|publisher=nasa.gov|date=2015-09-24}}</ref> The name of the nebula derives from the draped, filamentary structures within the nebula. The nebula is part of the Cygnus loop and its closeness compared to other nebulae make it an excellent target for amateur astronomers. The nebula has several names including: Witch’s broom nebula, Bridal Veil nebula, Cirrus nebula, or Filamentary nebula.

The '''Veil nebula''' is a large [[nebula]] in the [[constellation]] of [[Cygnus]].<ref name=nasa>{{cite web|url=https://www.nasa.gov/image-feature/veil-nebula-supernova-remnant|title=Veil Nebula Supernova Remnant|accessdate=December 23, 2019|publisher=nasa.gov|date=September 24, 2015}}</ref> The name of the nebula derives from the draped, filamentary structures within the nebula. The nebula is part of the Cygnus loop and its closeness compared to other nebulae make it an excellent target for amateur astronomers. The nebula has several names including: Witch’s broom nebula, Bridal Veil nebula, Cirrus nebula, or Filamentary nebula.

==History of observation==

==History of observation==

==Properties and structure==

==Properties and structure==

The nebula is situated 2,100 [[light year]]s away from [[Earth]], though some sources suggest it is closer at 1,470&nbsp;ly.<ref>{{cite web|url=https://phys.org/news/2018-11-cygnus-loop.html|title=The Cygnus Loop|accessdate=2019-12-23|publisher=phys.org|date=2018-11-27}}</ref><ref>

The nebula is situated 2,100 [[light year]]s away from [[Earth]], though some sources suggest it is closer at 1,470&nbsp;ly.<ref>{{cite web|url=https://phys.org/news/2018-11-cygnus-loop.html|title=The Cygnus Loop|accessdate=December 23, 2019|publisher=phys.org|date=November 27, 2018}}</ref><ref>

{{cite journal

{{cite journal

  |last1=Fesen |first1=R. A.

  |last1=Fesen |first1=R. A.

  |ref=harv

  |ref=harv

}} {{arXiv|1711.02174}}

}} {{arXiv|1711.02174}}

</ref> The nebula is around 110&nbsp;ly across, corresponding to an apparent size of 3 degrees.<ref>{{cite web|url=https://apod.nasa.gov/apod/ap191031.html|title=The Ghostly Veil Nebula|accessdate=2019-12-23|publisher=apod.nasa.gov|date=2019-10-31}}</ref> It covers an area of the night sky equal to around six full [[Moon]]s. The debris in the nebula is moving rapidly at roughly 600,000 kilometres per hour.<ref name=constellation-guide/> This results in shock fronts forming that heat the gas in the nebula to millions of [[kelvin]]. The material then glows as it cools. Although bright, the large area results in a low surface brightness and an OIII filter is recommended for observations.<ref>{{cite web|url=http://spider.seds.org/spider/Misc/veil.html|title=NGC 6960, 6979, 6992, 6995: The Veil Nebula|accessdate=2019-12-23|publisher=spider.seds.org}}</ref> The brightness of the nebula varies across the nebula due to variations in the [[density]] of the gas present in the nebula, with denser regions being brighter.<ref name=skyandtelescope>{{cite web|url=https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/explore-veil-nebula/|title=Explore the Veil Nebula|accessdate=2019-12-23|publisher=skyandtelescope.com|date=2018-09-15|author=Bob King}}</ref>

</ref> The nebula is around 110&nbsp;ly across, corresponding to an apparent size of 3 degrees.<ref>{{cite web|url=https://apod.nasa.gov/apod/ap191031.html|title=The Ghostly Veil Nebula|accessdate=December 23, 2019|publisher=apod.nasa.gov|date=October 31, 2019}}</ref> It covers an area of the night sky equal to around six full [[Moon]]s. The debris in the nebula is moving rapidly at roughly 600,000 kilometres per hour.<ref name=constellation-guide/> This results in shock fronts forming that heat the gas in the nebula to millions of [[kelvin]]. The material then glows as it cools. Although bright, the large area results in a low surface brightness and an OIII filter is recommended for observations.<ref>{{cite web|url=http://spider.seds.org/spider/Misc/veil.html|title=NGC 6960, 6979, 6992, 6995: The Veil Nebula|accessdate=December 23, 2019|publisher=spider.seds.org}}</ref> The brightness of the nebula varies across the nebula due to variations in the [[density]] of the gas present in the nebula, with denser regions being brighter.<ref name=skyandtelescope>{{cite web|url=https://www.skyandtelescope.com/astronomy-blogs/explore-night-bob-king/explore-veil-nebula/|title=Explore the Veil Nebula|accessdate=December 23, 2019|publisher=skyandtelescope.com|date=September 15, 2018|author=Bob King}}</ref>

Observations of the nebula in non-optical regions of the [[electromagnetic spectrum]] have revealed many interesting facts about the nebula. The nebula is a source of [[radio]] emissions and possess the designations W87 and Shapeless&nbsp;101 for this.<ref>{{cite web|url=https://www.britannica.com/place/Cygnus-Loop|title=Cygnis Loop|accessdate=2019-12-23|publisher=britannica.com}}</ref> It is also one of the largest and brightest sources of [[x-ray]]s in the night sky.<ref>

Observations of the nebula in non-optical regions of the [[electromagnetic spectrum]] have revealed many interesting facts about the nebula. The nebula is a source of [[radio]] emissions and possess the designations W87 and Shapeless&nbsp;101 for this.<ref>{{cite web|url=https://www.britannica.com/place/Cygnus-Loop|title=Cygnis Loop|accessdate=December 23, 2019|publisher=britannica.com}}</ref> It is also one of the largest and brightest sources of [[x-ray]]s in the night sky.<ref>

{{cite journal

{{cite journal

  |last1=McEntaffer |first1=R. L.

  |last1=McEntaffer |first1=R. L.

  |ref=harv

  |ref=harv

}} {{arXiv|0801.4552}}

}} {{arXiv|0801.4552}}

</ref><ref>{{cite web|url=https://heasarc.gsfc.nasa.gov/docs/suzaku/gallery/science/cygloop.html|title=Soft X-ray Emission from the Cygnus Loop|accessdate=2019-12-23|publisher=heasarc.gsfc.nasa.gov|date=2007-07-02}}</ref> The x-ray spectrum of the nebula has indicated it contains the [[element]]s [[sulfur]], [[oxygen]] and [[hydrogen]]. The supernova remnant at the centre of the nebula is an x-ray source with designation Cygnus X-5.<ref name=constellation-guide/> When viewed in [[ultraviolet]], gas that has been heated to extreme temperatures by shockwaves is easily identifiable.<ref>{{cite web|url=https://www.nasa.gov/mission_pages/galex/pia15415.html|title=Cygnus Loop Nebula|accessdate=2019-12-23|publisher=nasa.gov|date=2012-03-22}}</ref>

</ref><ref>{{cite web|url=https://heasarc.gsfc.nasa.gov/docs/suzaku/gallery/science/cygloop.html|title=Soft X-ray Emission from the Cygnus Loop|accessdate=December 23, 2019|publisher=heasarc.gsfc.nasa.gov|date=July 02, 2007}}</ref> The x-ray spectrum of the nebula has indicated it contains the [[element]]s [[sulfur]], [[oxygen]] and [[hydrogen]]. The supernova remnant at the centre of the nebula is an x-ray source with designation Cygnus X-5.<ref name=constellation-guide/> When viewed in [[ultraviolet]], gas that has been heated to extreme temperatures by shockwaves is easily identifiable.<ref>{{cite web|url=https://www.nasa.gov/mission_pages/galex/pia15415.html|title=Cygnus Loop Nebula|accessdate=December 23, 2019|publisher=nasa.gov|date=March 22, 2012}}</ref>

The nebula is large and is commonly considered to be composed of three regions, the Eastern Veil nebula, the West Veil nebula and Fleming’s Triangle (sometimes called Pickering’s Triangle).<ref name=constellation-guide/> The regions and features of the nebula have numerous designations in the [[New General Catalogue]] including NGC&nbsp;6960, NGC&nbsp;6992, NGC&nbsp;6995, NGC&nbsp;6974, and NGC&nbsp;6979. Additionally the southern region of the Eastern Veil nebula has the designation IC&nbsp;1340.

The nebula is large and is commonly considered to be composed of three regions, the Eastern Veil nebula, the West Veil nebula and Fleming’s Triangle (sometimes called Pickering’s Triangle).<ref name=constellation-guide/> The regions and features of the nebula have numerous designations in the [[New General Catalogue]] including NGC&nbsp;6960, NGC&nbsp;6992, NGC&nbsp;6995, NGC&nbsp;6974, and NGC&nbsp;6979. Additionally the southern region of the Eastern Veil nebula has the designation IC&nbsp;1340.