N44 (emission nebula)

{{Short description|Emission nebula in the constellation Dorado}}

{{Other uses|N44 (disambiguation){{!}}N44}}

{{Infobox nebula

|name = N44

|image = ESO-N44-central region-LMC-phot-31b-03-fullres.jpg

|caption = The central region of N44

|credit =

|type = emission

|type2 = superbubble

|epoch = J2000.0

|subtype =

|class =

|ra = {{RA|05|22|06.9}}

|dec = {{DEC|-67|56|46}}

|dist_ly = ~160,000-170,000

|dist_pc =

|dist_z =

|appmag_v =

|appdia =

|size_v =

|constellation = Dorado

|radius_ly = ~500

|radius_pc =

|dimensions =

|absmag_v =

|notes =

|names =

}}

File:LHA 120-N 44.jpg

N44 is an emission nebula with superbubble structure located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way in the constellation Dorado.{{cite web |url = http://xmm.esac.esa.int/external/xmm_science/x-ray-symposium/173952_hn_n44inlmc.pdf |title = Exploring High Energy Activities in the Superbubble N44 With XMM-NEWTON |author = H. Nakajima |others = H. Yamaguchi, M. Ueno, A. Bamba, and K. Koyama |publisher = European Space Agency |date = 26 September 2005 |work = The X-Ray Universe Symposium |access-date = 10 May 2012 |archive-date = 14 July 2014 |archive-url = https://web.archive.org/web/20140714122902/http://xmm.esac.esa.int/external/xmm_science/x-ray-symposium/173952_hn_n44inlmc.pdf |url-status = dead }}{{cite web |url = http://www.gemini.edu/index.php?q=node/171 |title = Gemini Looks Down the Mouth of an Interstellar Cavern |publisher = Gemini Observatory |date = 4 January 2006 |access-date = 10 May 2012 |last = Michaud |first = Peter}} Originally catalogued in Karl Henize's "Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds" of 1956, it is approximately 1,000 light-years wide and 160,000-170,000 light-years distant.{{cite web |url = http://www.eso.org/public/images/eso0332b/ |title = N44 in the Large Magellanic Cloud (Central Region) |publisher = ESO |date = 3 November 2003 |access-date = 7 May 2012}} N44 has a smaller bubble structure inside known as N44F. The superbubble structure of N44 itself is shaped by the radiation pressure of a 40-star group located near its center; the stars are blue-white, very luminous, and incredibly powerful.{{cite web |url = http://www.eso.org/public/news/eso0332/ |title = Roses in the Southern Sky |date = 3 November 2003 |publisher = ESO |access-date = 7 May 2012}} N44F has been shaped in a similar manner; it has a hot, massive central star with an unusually powerful stellar wind that moves at 7 million kilometers per hour. This is because it loses material at 100 million times the rate of the Sun, or approximately 1,000,000,000,000,000 tons per year. However, varying density in the N44 nebula has caused the formation of several dust pillars that may conceal star formation.{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1=Wilkins |first1=Jamie |last2=Dunn |first2 = Robert |publisher = Firefly Books |date = 2006 |edition = 1st |location=Buffalo, New York |isbn = 978-1-55407-175-3}} This variable density is likely caused by previous supernovae in the vicinity of N44; many of the stars that have shaped it will eventually also end as supernovae. The past effects of supernovae are also confirmed by the fact that N44 emits x-rays.{{Cite APOD |title = The N44 Superbubble |date = 6 February 2006 |access-date = 10 May 2012}}{{cite web |url = http://www.eso.org/public/images/eso9931b/ |title = Detail of N44 in the Large Magellanic Cloud |date = 22 June 1999 |publisher = ESO |access-date = 7 May 2012}}

N44 is classified as an emission nebula because it contains large regions of ionized hydrogen. However, the three strongest emission lines in the nebula are singly ionized oxygen atoms, which emit at an ultraviolet wavelength of 372.7 nm, doubly-ionized oxygen atoms, which emit at a blue-green wavelength of 500.7 nm, and neutral hydrogen atoms, which emit the hydrogen-alpha line at a red wavelength of 656.2 nm.{{Cite APOD |title = The N44 Emission Nebula |date = 13 February 2006 |access-date = 7 May 2012}}