View source for NGC 1999

{{short description|Reflection nebula in the constellation Orion}}
{{Infobox nebula
| name = [[New General Catalogue|NGC]] 1999
| image = Ngc1999.jpg
| caption= [[Hubble Space Telescope|Hubble]]/[[Wide Field and Planetary Camera 2|WFPC2]] captures the void in 2000
| type = reflection
| epoch = [[J2000]]
| ra = {{RA|05|36|27.00}}
| dec = {{DEC|-06|43|18.0}}
| dist_ly = 1,500
| appmag_v = 
| size_v = 1.5 [[Minute of arc|arcmins]]
| constellation  = [[Orion (constellation)|Orion]]
| radius_ly = ~0.3
| absmag_v = 
| notes = 
| names =
}}
[[File:NGC1999 Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg|thumb|The overall nebula with smaller hole shown in context]]
'''NGC 1999,''' also known as '''The Cosmic Keyhole''',<ref>{{Cite web |title=Hubble Peers at Mysterious Cosmic ‘Keyhole’ - NASA Science |url=https://science.nasa.gov/missions/hubble/hubble-peers-at-mysterious-cosmic-a-keyhole/ |access-date=2023-12-20 |website=science.nasa.gov |language=en}}</ref><ref>{{Cite web |last=information@eso.org |title=Cosmic Keyhole |url=https://www.spacetelescope.org/images/potw2243a/ |access-date=2023-12-20 |website=www.spacetelescope.org |language=en}}</ref> is a dust-filled [[bright nebula]] with a vast hole of empty space represented by a black patch of sky, as can be seen in the photograph. It is a [[reflection nebula]], and shines from the light of the [[variable star]] [[V380 Orionis]].  

It was previously believed that the black patch was a dense cloud of dust and gas which blocked light that would normally pass through, called a [[dark nebula]]. Analysis of this patch by the infrared telescope [[Herschel Space Observatory|Herschel]] (October 9, 2009), which has the capability of penetrating such dense cloud material, resulted in continued black space. This led to the belief that either the cloud material was immensely dense or that an unexplained phenomenon had been detected. 

With support from ground-based observations done using the [[Submillimetre astronomy|submillimeter]] [[bolometer]] cameras on the [[Atacama Pathfinder Experiment]] [[radio telescope]] (November 29, 2009) and the [[Nicholas U. Mayall Telescope|Mayall (Kitt Peak)]] and [[Magellan Telescopes|Magellan telescopes]] (December 4, 2009), it was determined that the patch looks black not because it is an extremely dense pocket of gas, but because it is truly empty. The exact cause of this phenomenon is still being investigated, although it has been hypothesized that narrow jets of gas from some of the young stars in the region punctured the sheet of dust and gas, as well as, powerful radiation from a nearby mature star may have helped to create the hole. Researchers believe this discovery should lead to a better understanding of the entire star forming process.<ref name=msnbc/><ref name=stanke/>

It is located 1,500 [[light-year]]s away from Earth in the [[constellation]] [[Orion (constellation)|Orion]].<ref name=hubble/> [[HH 1/2]], the first recognized [[Herbig–Haro object|Herbig-Haro Object]], is located near NGC 1999.<ref>{{Cite journal|last1=Bally|first1=John|last2=Heathcote|first2=Steve|last3=Reipurth|first3=Bo|last4=Morse|first4=Jon|last5=Hartigan|first5=Patrick|last6=Schwartz|first6=Richard|date=May 2002|title=Hubble Space Telescope Observations of Proper Motions in Herbig-Haro Objects 1 and 2|journal=The Astronomical Journal |language=en|volume=123|issue=5|pages=2627–2657|doi=10.1086/339837|bibcode=2002AJ....123.2627B|issn=0004-6256|doi-access=free}}</ref>

==References==
{{reflist|refs=

<ref name=stanke>{{cite journal |doi=10.1051/0004-6361/201014612 |arxiv=1005.2202|title=Hier ist wahrhaftig ein Loch im Himmel|journal=Astronomy and Astrophysics|volume=518|pages=L94|year=2010|last1=Stanke|first1=T|last2=Stutz|first2=A. M|last3=Tobin|first3=J. J|last4=Ali|first4=B|last5=Megeath|first5=S. T|last6=Krause|first6=O|last7=Linz|first7=H|last8=Allen|first8=L|last9=Bergin|first9=E|last10=Calvet|first10=N|author10-link=Nuria Calvet|last11=Di Francesco|first11=J|last12=Fischer|first12=W. J|last13=Furlan|first13=E|last14=Hartmann|first14=L|last15=Henning|first15=T|last16=Manoj|first16=P|last17=Maret|first17=S|last18=Muzerolle|first18=J|last19=Myers|first19=P. C|last20=Neufeld|first20=D|last21=Osorio|first21=M|last22=Pontoppidan|first22=K|last23=Poteet|first23=C. A|last24=Watson|first24=D. M|last25=Wilson|first25=T|bibcode=2010A&A...518L..94S|s2cid=118725991}}</ref>

<ref name=hubble>{{cite web |url=http://hubblesite.org/newscenter/archive/releases/2000/10/fastfacts/ |title=Fast Facts: Hubble Takes a Close-up View of a Reflection Nebula in Orion |access-date=2008-03-15}}</ref>

<ref name=msnbc>{{cite web |url=https://www.nbcnews.com/id/wbna37088640 |title=Telescope discovers surprising hole in space |publisher=NBC News by [[Space.com]] |date=2010-05-11 |access-date=2018-03-07}}</ref>

}}

==External links==
*{{commonscat-inline}}
*{{cite news |url=http://news.nationalgeographic.com/news/2010/05/100512-science-space-black-hole-herschel-stars/ |archive-url=https://web.archive.org/web/20100513034958/http://news.nationalgeographic.com/news/2010/05/100512-science-space-black-hole-herschel-stars/ |url-status=dead |archive-date=May 13, 2010 |publisher=National Geographic |title=Hole in Space Found by Orbiting Telescope |author=Andrew Fazekas |date=May 12, 2010 |access-date=2018-03-07}}

{{Ngc20}}
{{Orion (constellation)}}
[[Category:NGC objects|1999]]
[[Category:Reflection nebulae]]
[[Category:Orion molecular cloud complex]]
[[Category:Orion (constellation)]]