Sharpless 264, also known as the Lambda Orionis Ring, is a

molecular cloud A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen ...

and

H II region An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds ...

, which can be seen in the northern region of the

Orion molecular cloud complex The Orion molecular cloud complex (or, simply, the Orion complex) is a star-forming region with stellar ages ranging up to 12 Myr. Two giant molecular clouds are a part of it, Orion A and Orion B. The stars currently forming within the complex a ...

(OMCC), in the constellation of Orion. The OMCC is one of the best-known

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

regions and the closest sector of the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

to the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

where high-mass

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s are born. The

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

is named after its main star, λ Orionis, a

blue giant In astronomy, a blue giant is a hot star with a luminosity class of III (giant star, giant) or II (bright giant). In the standard Hertzsprung–Russell diagram, these stars lie above and to the right of the main sequence. The term applies to a ...

responsible for the

ionization Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule i ...

of the surrounding material.Mathieu, R. D.
''The λ Orionis Star Forming Region''
''in Handbook of Star Forming Regions'', Volume I: The Northern Sky ASP Monograph Publications, vol. 4, Bo Reipurth, December 2008, p. 757, . It is also sometimes called the Angelfish Nebula due to its resemblance as to its lighter areas (pink to peach colour) to an angelfish. In the infrared its ionized boundaries are that which appears, instead.

Observations

λ Orionis (also known as Meissa or Heka) at about 1,100 light-years is the

representing the head of Orion and can be found to the

north North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

of the quadrangle defined by the stars

Betelgeuse Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of Orion ...

Bellatrix Bellatrix is the third-brightest star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse (Alpha Orionis). It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly va ...

Rigel Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...

and

Saiph Saiph , designation Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the sta ...

. This star can be found at the centre of open cluster Collinder 69 composed of fourth and fifth-magnitude young hot stars, visible to the naked eye. It can be resolved with a pair of

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

. The rest of the cluster and associated nebula spans a few hundred light-years centred about 1400

light-years A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

away. The broad nebula shown is not visible unaided, with

or small amateur

telescopes A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

. It becomes clear in long-exposure

photographs A photograph (also known as a photo, image, or picture) is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensor, such as a CCD or a CMOS chip. Most photographs are now created ...

, such as in the first illustration on this page.

Orange giant A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...

φ² Orionis, while appearing to be surrounded by the Ring, is merely a foreground object at only about 116 light years from Earth. HD 34989 is a blue-white main sequence star, visible magnified only, just outside the Ring. It has a small nebulous cloud more geared towards the near-infrared than other parts of the neighbouring ionized regions across the Ring.

Gallery

Orion%27s_Big_Head_Revealed_in_Infrared.jpg, The ring shows its

status in the infrared — this image includes the very bright source of infrared and near-infrared Betelgeuse, therefore blue-white when shown converted to visible light. Sig07-006.jpg,

Barnard 30 Barnard 30 is a dark cloud in the Lambda Orionis ring, north of Lambda Orionis, also called Meissa. The region is about 1300 light years from Earth. The Barnard 30 cloud is one of the regions in the Lambda Orionis Ring where the population of you ...

, a part of the Lambda Orionis Ring seen by the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

. Young stars are forming in this region. Barnard 35 Spitzer.jpg, Barnard 35, a part of the Lambda Orionis Ring seen by the

. The Herbig-Haro Object HH 175 is part of this structure. The bright star on the lower right part of the image is

FU Orionis FU Orionis is a variable and binary star system in the constellation of Orion, that in 1937 rose in apparent visual magnitude from 16.5 to 9.6, and has since been around magnitude 9. The name ''FU Orionis'' is a variable star designatio ...

. HD 34989 Spitzer.jpg, The star HD 34989 is surrounded by material that is part of the Lambda Orionis Ring. The images of this region were taken with the

References

External links

CCD Images of the Sharpless CatalogGalaxy Map
{{Sh2 objects Sharpless objects H II regions Orion molecular cloud complex Orion (constellation)