Sh 2-264

Sharpless 264,also known as theLambda Orionis Ring,is amolecular cloudandH II region,which can be seen in the northern region of theOrion molecular cloud complex(OMCC), in the constellation ofOrion.The OMCC is one of the best-knownstar formationregions and the closest sector of theMilky Wayto theSolar Systemwhere high-massstarsare born. Thenebulais named after its main star,λ Orionis,ablue giantresponsible for theionizationof the surrounding material.^[1]It is also sometimes called theAngelfish Nebuladue to its resemblance as to its lighter areas (pink to peach colour) to anangelfish.In the infrared its ionized boundaries are that which appears, instead.

Observations

λ Orionis(also known asMeissaorHeka) at about 1,100 light-years is thestarrepresenting the head ofOrionand can be found to thenorthof the quadrangle defined by the starsBetelgeuse,Bellatrix,RigelandSaiph.This star can be found at the centre of open clusterCollinder 69composed of fourth and fifth-magnitude young hot stars, visible to the naked eye. It can be resolved with a pair ofbinoculars.The rest of the cluster and associated nebula spans a few hundred light-years centred about 1400light-yearsaway.

The broad nebula shown is not visible unaided, withbinocularsor small amateurtelescopes.It becomes clear in long-exposurephotographs,such as in the first illustration on this page.

Orange giant φ²Orionis,while appearing to be surrounded by the Ring, is merely a foreground object at only about 116 light years from Earth.

HD 34989is ablue-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

The ring shows itsH II regionstatus 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.
Barnard 30,a part of the Lambda Orionis Ring seen by theSpitzer Space Telescope.Young stars are forming in this region.
Barnard 35,a part of the Lambda Orionis Ring seen by theSpitzer Space Telescope.TheHerbig-Haro Object HH 175is part of this structure. The bright star on the lower right part of the image isFU Orionis.
The starHD 34989is surrounded by material that is part of the Lambda Orionis Ring. The images of this region were taken with theSpitzer Space Telescope.

References

^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,ISBN 978-1-58381-670-7.

External links

[1] 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,ISBN 978-1-58381-670-7.

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