Omega Nebula
Encyclopedia
The Omega Nebula, also known as the Swan Nebula, Checkmark Nebula, Lobster Nebula, and the Horseshoe Nebula (catalogued as Messier 17 or M17 and as NGC 6618) is an H II region
in the constellation
Sagittarius
. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier
catalogued it in 1764. It is located in the rich starfields of the Sagittarius area of the Milky Way
.
The Omega Nebula is between 5,000 and 6,000 light-year
s from Earth
and it spans some 15 light-years in diameter
. The cloud of interstellar matter
of which this nebula
is a part is roughly 40 light-years in diameter. The total mass
of the Omega Nebula is an estimated 800 solar mass
es.
An open cluster
of 35 stars lies embedded in the nebulosity and causes the gas
es of the nebula to shine due to radiation
from these hot, young stars.
The Swan portion of M17, the Omega Nebula in the Sagittarius nebulosity
is said to resemble a barber’s pole
.
in 1833, and published in 1836. He described the nebula as such:
A second, more detailed sketch was made during his visit to South Africa
in 1837. The nebula was also studied by Johann von Lamont
and separately by an undergraduate at Yale College
, Mr Mason, starting from around 1836. When Herschel published his 1837 sketch in 1847, he wrote:
Sketches were also made by William Lassell
in 1862 using his four-foot telescope
at Malta
, and by M. Trouvelot from Cambridge, Massachusetts
and Edward Singleton Holden
in 1875 using the twenty-six inch Clark refractor at the United States Naval Observatory
.
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived, blue stars forged in these regions emit copious amounts of ultraviolet light, ionizing the surrounding gas...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Sagittarius
Sagittarius (constellation)
Sagittarius is a constellation of the zodiac, the one containing the galactic center. Its name is Latin for the archer, and its symbol is , a stylized arrow. Sagittarius is commonly represented as a centaur drawing a bow...
. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier
Charles Messier
Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects"...
catalogued it in 1764. It is located in the rich starfields of the Sagittarius area of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
.
The Omega Nebula is between 5,000 and 6,000 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
and it spans some 15 light-years in diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
. The cloud of interstellar matter
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
of which this nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
is a part is roughly 40 light-years in diameter. The total mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of the Omega Nebula is an estimated 800 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es.
An open cluster
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist...
of 35 stars lies embedded in the nebulosity and causes the gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
es of the nebula to shine due to radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
from these hot, young stars.
The Swan portion of M17, the Omega Nebula in the Sagittarius nebulosity
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
is said to resemble a barber’s pole
Barber's pole
A barber's pole is a type of sign used by barbers to signify the place or shop where they perform their craft. The trade sign is, by a tradition dating back to the Middle Ages, a staff or pole with a helix of colored stripes...
.
Early research
The first attempt to accurately draw the nebula (as part of a series of sketches of nebulae) was made by John HerschelJohn Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
in 1833, and published in 1836. He described the nebula as such:
A second, more detailed sketch was made during his visit to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in 1837. The nebula was also studied by Johann von Lamont
Johann von Lamont
Johann von Lamont was a Scottish-German astronomer and physicist.-Biography:Von Lamont was born John Lamont at Corriemulzie near Inverey in Aberdeenshire, Scotland. The son of Robert Lamont and Elizabeth Ewan, his education began at the local school in Inverey, near Braemar...
and separately by an undergraduate at Yale College
Yale College
Yale College was the official name of Yale University from 1718 to 1887. The name now refers to the undergraduate part of the university. Each undergraduate student is assigned to one of 12 residential colleges.-Residential colleges:...
, Mr Mason, starting from around 1836. When Herschel published his 1837 sketch in 1847, he wrote:
Sketches were also made by William Lassell
William Lassell
William Lassell FRS was an English merchant and astronomer.Born in Bolton and educated in Rochdale after the death of his father, he was apprenticed from 1814 to 1821 to a merchant in Liverpool. He then made his fortune as a beer brewer, which enabled him to indulge his interest in astronomy...
in 1862 using his four-foot telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
at Malta
Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...
, and by M. Trouvelot from Cambridge, Massachusetts
Cambridge, Massachusetts
Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, an important center of the Puritan theology embraced by the town's founders. Cambridge is home to two of the world's most prominent...
and Edward Singleton Holden
Edward Singleton Holden
Edward Singleton Holden was an American astronomer.-Early years:He was born in St. Louis, Missouri in 1846 to Jeremiah and Sarah Holden. From 1862-66, he attended Washington University in St. Louis, where he obtained a B.S. degree...
in 1875 using the twenty-six inch Clark refractor at the United States Naval Observatory
United States Naval Observatory
The United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation, and Timing for the U.S. Navy and the U.S. Department of Defense...
.
See also
- Messier ObjectMessier objectThe Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. The original motivation of the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets...
- List of Messier objects
- New General CatalogueNew General CatalogueThe New General Catalogue of Nebulae and Clusters of Stars is a well-known catalogue of deep sky objects in astronomy. It contains 7,840 objects, known as the NGC objects...