Veil Nebula

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Veil Nebula
Diffuse nebula
supernova remnant
Veil Nebula - NGC6960.jpg
Western Veil nebula
Observation data: J2000.0 epoch
Right ascension 20h 45m 38.0s [1]
Declination +30° 42′ 30″ [1]
Distance2400 [2]   ly
Apparent magnitude (V)7.0
Apparent dimensions (V)3 degrees (diameter)
Constellation Cygnus
Physical characteristics
Radius 50-65[ citation needed ] ly
Designations NGC 6960, [1] 6992, [1] 6995, [1] 6974, and 6979, IC 1340, Cygnus Loop, Cirrus Nebula, [1] Filamentary Nebula, [1] Witch's Broom Nebula (NGC 6960), [3] Caldwell 33/34
See also: Lists of nebulae

The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. [4]

Contents

It constitutes the visible portions of the Cygnus Loop, [5] 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. [2] At the time of the explosion, the supernova would have appeared brighter than Venus in the sky, and visible in the daytime. [6] The remnants have since expanded to cover an area of the sky roughly 3 degrees in diameter (about 6 times the diameter, and 36 times the area, of the full Moon). [4] While previous distance estimates have ranged from 1200 to 5800 light-years, a recent determination of 2400 light-years is based on direct astrometric measurements. [2] (The distance estimates affect also the estimates of size and age.)

The Hubble Space Telescope captured several images of the nebula. The analysis of the emissions from the nebula indicates the presence of oxygen, sulfur, and hydrogen. [7] The Cygnus Loop is also a strong emitter of radio waves and x-rays. [8]

Components

NASA photograph of the Cygnus Loop in ultraviolet light, with labels for well-known features. (25 November 2012) Cygnus Loop Labeled.png
NASA photograph of the Cygnus Loop in ultraviolet light, with labels for well-known features. (25 November 2012)

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. [9] There are three main visual components:

NGC 6974 and NGC 6979 are luminous knots in a fainter patch of nebulosity on the northern rim between NGC 6992 and Pickering's Triangle. [12] [13]

Observation

George Willis Ritchey image of what he called the Great Nebula in Cygnus (In modern times the Veil Nebula); taken with the two-foot reflecting telescope with 3 hours exposure at the Yerkes Observatory in 1901. Annual report of the Board of Regents of the Smithsonian Institution (1901) (17813060474).jpg
George Willis Ritchey image of what he called the Great Nebula in Cygnus (In modern times the Veil Nebula); taken with the two-foot reflecting telescope with 3 hours exposure at the Yerkes Observatory in 1901.

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." [14]

When finely resolved, some parts of the nebula appear to be rope-like filaments. The standard explanation is that the shock waves are so thin, less than one part in 50,000 of the radius, [15] that the shell is visible only when viewed exactly edge-on, giving the shell the appearance of a filament. At the estimated distance of 2400 light-years, the nebula has a radius of 65 light-years (a diameter of 130 light-years). The thickness of each filament is 1⁄50,000th of the radius, or about 4 billion miles, roughly the distance from Earth to Pluto. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined.

Even though the nebula has a relatively bright integrated magnitude of 7, it is spread over so large an area that the surface brightness is quite low, so the nebula is notorious among astronomers as being difficult to see. However, an observer can see the nebula clearly in a telescope using an O-III astronomical filter (isolating the wavelength of light from doubly ionized oxygen), as almost all light from this nebula is emitted at this wavelength. An 8-inch (200 mm) telescope equipped with an O-III filter shows the delicate lacework apparent in photographs. Smaller telescopes with an O-III filter can show the nebula as well, and some[ who? ] argue that it can be seen without any optical aid except an O-III filter held up to the eye.[ citation needed ]

The brighter segments of the nebula have the New General Catalogue designations NGC 6960, 6974, 6979, 6992, and 6995. The easiest segment to find is 6960, which runs behind 52 Cygni, a star that can be seen with the naked eye. NGC 6992 and 6995 are objects on the eastern side of the loop which are also relatively easy to see. NGC 6974 and NGC 6979 are visible as knots in an area of nebulosity along the northern rim. Pickering's Triangle is much fainter and has no NGC number (though 6979 is occasionally used to refer to it). It was discovered photographically in 1904 by Williamina Fleming (after the New General Catalogue was published), but credit went to Edward Charles Pickering, the director of her observatory, as was the custom of the day.

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. [16] [17]

See also

Related Research Articles

<span class="mw-page-title-main">Cygnus (constellation)</span> Constellation in the northern celestial hemisphere

Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.

<span class="mw-page-title-main">Emission nebula</span> Nebula formed of ionized gases that emit light of various wavelengths

An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them.

<span class="mw-page-title-main">Tarantula Nebula</span> H II region in the constellation Dorado

The Tarantula Nebula is a large H II region in the Large Magellanic Cloud (LMC), forming its south-east corner.

<span class="mw-page-title-main">Eagle Nebula</span> Open cluster in the constellation Serpens

The Eagle Nebula is a young open cluster of stars in the constellation Serpens, discovered by Jean-Philippe de Cheseaux in 1745–46. Both the "Eagle" and the "Star Queen" refer to visual impressions of the dark silhouette near the center of the nebula, an area made famous as the "Pillars of Creation" imaged by the Hubble Space Telescope. The nebula contains several active star-forming gas and dust regions, including the aforementioned Pillars of Creation. The Eagle Nebula lies in the Sagittarius Arm of the Milky Way.

<span class="mw-page-title-main">North America Nebula</span> Emission nebula in the constellation Cygnus

The North America Nebula is an emission nebula in the constellation Cygnus, close to Deneb. It is named because its shape resembles North America.

<span class="mw-page-title-main">Eskimo Nebula</span> Planetary nebula in the constellation Gemini

The Eskimo Nebula, also known as the Clown-faced Nebula, Lion Nebula, or Caldwell 39, is a bipolar double-shell planetary nebula (PN). It was discovered by astronomer William Herschel in 1787. The formation resembles a person's head surrounded by a parka hood. It is surrounded by gas that composed the outer layers of a Sun-like star. The visible inner filaments are ejected by a strong wind of particles from the central star. The outer disk contains unusual, light-year-long filaments.

<span class="mw-page-title-main">Centaurus A</span> Radio galaxy in the constellation Centaurus

Centaurus A is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance. NGC 5128 is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.

<span class="mw-page-title-main">Whirlpool Galaxy</span> Galaxy in the constellation Canes Venatici

The Whirlpool Galaxy, also known as Messier 51a (M51a) or NGC 5194, is an interacting grand-design spiral galaxy with a Seyfert 2 active galactic nucleus. It lies in the constellation Canes Venatici, and was the first galaxy to be classified as a spiral galaxy. It is 7.22 megaparsecs away and 23.58 kiloparsecs (76,900 ly) in diameter.

<span class="mw-page-title-main">NGC 281</span> Emission nebula in the constellation Cassiopeia

NGC 281, IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way's Perseus Spiral Arm. This 20×30 arcmin sized nebulosity is also associated with open cluster IC 1590, several Bok globules and the multiple star, B 1. It collectively forms Sh2-184, spanning over a larger area of 40 arcmin. A recent distance from radio parallaxes of water masers at 22 GHz made during 2014 is estimated it lies 2.82±0.20 kpc. from us. Colloquially, NGC 281 is also known as the Pacman Nebula for its resemblance to the video game character.

<span class="mw-page-title-main">Saturn Nebula</span> Planetary nebula in the constellation Aquarius

The Saturn Nebula is a planetary nebula in the constellation Aquarius. It appears as a greenish-yellowish hue in a small amateur telescope. It was discovered by William Herschel on September 7, 1782, using a telescope of his own design in the garden at his home in Datchet, England, and was one of his earliest discoveries in his sky survey. The nebula was originally a low-mass star that ejected its layers into space, forming the nebula. The central star is now a bright white dwarf star of apparent magnitude 11.5. The Saturn Nebula gets its name from its superficial resemblance to the planet Saturn with its rings nearly edge-on to the observer. It was so named by Lord Rosse in the 1840s, when telescopes had improved to the point that its Saturn-like shape could be discerned. William Henry Smyth said that the Saturn Nebula was one of Struve's nine "Rare Celestial Objects".

<span class="mw-page-title-main">NGC 6946</span> Galaxy in the constellations Cepheus & Cygnus

NGC 6946, sometimes referred to as the Fireworks Galaxy, is a face-on intermediate spiral galaxy with a small bright nucleus, whose location in the sky straddles the boundary between the northern constellations of Cepheus and Cygnus. Its distance from Earth is about 25.2 million light-years or 7.72 megaparsecs, similar to the distance of M101 in the constellation Ursa Major. Both were once considered to be part of the Local Group, but are now known to be among the dozen bright spiral galaxies near the Milky Way but beyond the confines of the Local Group. NGC 6946 lies within the Virgo Supercluster.

<span class="mw-page-title-main">NGC 891</span> Galaxy in the constellation Andromeda

NGC 891 is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October 6, 1784. The galaxy is a member of the NGC 1023 group of galaxies in the Local Supercluster. It has an H II nucleus.

<span class="mw-page-title-main">Cygnus Loop</span> Supernova remnant in the constellation of Cygnus

The Cygnus Loop is a large supernova remnant (SNR) in the constellation Cygnus, an emission nebula measuring nearly 3° across. Some arcs of the loop, known collectively as the Veil Nebula or Cirrus Nebula, emit in the visible electromagnetic range. Radio, infrared, and X-ray images reveal the complete loop.

<span class="mw-page-title-main">Sh2-279</span> Emission nebula in the constellation Orion

Sh2-279 is an HII region and bright nebulae that includes a reflection nebula located in the constellation Orion. It is the northernmost part of the asterism known as Orion's Sword, lying 0.6° north of the Orion Nebula. The reflection nebula embedded in Sh2-279 is popularly known as the Running Man Nebula.

<span class="mw-page-title-main">Caldwell catalogue</span> Astronomical objects catalogued by Patrick Moore

The Caldwell catalogue is an astronomical catalogue of 109 star clusters, nebulae, and galaxies for observation by amateur astronomers. The list was compiled by Patrick Moore as a complement to the Messier catalogue.

<span class="mw-page-title-main">NGC 7252</span> Peculiar galaxy in the constellation Aquarius

NGC 7252 is a peculiar galaxy resulting from an interaction between two galaxies that started a billion years ago. It is located 220 million light years away in the constellation Aquarius. It is also called Atoms for Peace Galaxy, a nickname which comes from its loop-like structure, made of stars, that resembles a classic diagram of an electron orbiting an atomic nucleus.

<span class="mw-page-title-main">NGC 6884</span> Planetary nebula in the constellation in the constellation Cygnus

NGC 6884 is a planetary nebula located in the constellation Cygnus, less than a degree to the southwest of the star Ο1 Cygni. It lies at a distance of approximately 12.5 kly from the Sun. The nebula was discovered on May 8, 1883, by American astronomer Edward C. Pickering.

<span class="mw-page-title-main">N11 (emission nebula)</span> Emission nebula in the constellation Dorado

N11 is the brightest emission nebula in the north-west part of the Large Magellanic Cloud in the Dorado constellation. The N11 complex is the second largest H II region of that galaxy, the largest being the Tarantula Nebula. It covers an area approximately 6 arc minutes across. It has an elliptical shape and consists of a large bubble, generally clear interstellar area, surrounded by nine large nebulae. It was named by Karl Henize in 1956.

<span class="mw-page-title-main">NGC 6910</span> Open cluster in the constellation Cygnus

NGC 6910 is an open cluster in the constellation Cygnus. It was discovered by William Herschel on October 17, 1786. The cluster was also observed by John Herschel on September 18, 1828. It is a poor cluster with prominent central concentration and Trumpler class I2p. NGC 6910 is the core cluster of the stellar association Cygnus OB9.

References

  1. 1 2 3 4 5 6 7 "NGC 6960". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2007-01-02.
  2. 1 2 3 Fesen, Robert A.; Weil, Kathryn E.; Cisneros, Ignacio A.; Blair, William P.; Raymond, John C. (2018). "The Cygnus Loop's distance, properties, and environment-driven morphology". Monthly Notices of the Royal Astronomical Society. 481 (2): 1786–1798. arXiv: 1809.01713 . Bibcode:2018MNRAS.481.1786F. doi:10.1093/mnras/sty2370. S2CID   119000958.
  3. ↑ Nemiroff, R.; Bonnell, J., eds. (1 January 2007). "NGC 6960: The Witch's Broom Nebula". Astronomy Picture of the Day . NASA . Retrieved 2007-01-02.
  4. 1 2 Loff, Sarah (24 September 2015). "Veil Nebula Supernova Remnant". NASA . Retrieved 6 September 2018.
  5. ↑ Burnham, Robert (1978). Burnham's Celestial Handbook . New York: Dover. p.  800–811. ISBN   978-0-486-23568-4.
  6. ↑ King, Bob (5 September 2018). "Explore the Veil Nebula". Sky & Telescope. Retrieved 12 November 2020.
  7. ↑ "Pickering's Triangle in the Veil". NASA . Astronomy Picture of the Day. 17 September 2015. Retrieved 6 September 2018.
  8. 1 2 "Cygnus Loop". Encyclopaedia Britannica . Retrieved 6 September 2018.
  9. ↑ Tirion; Rappaport; Lovi (1991) [1987]. Uranometria 2000. Vol. 1. Richmond, VA: William–Bell, Inc. p. 120. ISBN   978-0-943396-14-9.
  10. 1 2 Trusock, Tom. "§"The Veil"". Cloudy Nights Telescope Reviews. Small Wonders: Cygnus ...
  11. ↑ Frommert, Hartmut. "NGC 6960, 6979, 6992, 6995: Veil Nebula". spider.seds.org.
  12. ↑ "NGC/IC Project". Results for NGC 6974. Retrieved 2010-12-03.
  13. ↑ "NGC/IC Project". Results for NGC 6979. Retrieved 2010-12-03.
  14. ↑ Bratton, Mark (2011). The Complete Guide to the Herschel Objects. Cambridge University Press. ISBN   9781107376854 – via Google Books.
  15. ↑ Blair, William. "Cygnus Loop HST Photo Release". William Blair Homepage at Johns Hopkins University. Archived from the original on 2014-07-28. Retrieved 2010-11-29.
  16. ↑ "Revisiting the Veil Nebula". phys.org. ESA/Hubble Information Centre. 24 September 2015. Retrieved 26 June 2020.
  17. ↑ "Moving filaments of the Veil Nebula". spacetelescope.org. NASA. 24 September 2015. Retrieved 26 June 2020.
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