IC 434
Emission nebula in the constellation Orion
title: "IC 434" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["emission-nebulae", "ic-objects", "orion-(constellation)", "orion-molecular-cloud-complex"] description: "Emission nebula in the constellation Orion" topic_path: "general/emission-nebulae" source: "https://en.wikipedia.org/wiki/IC_434" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Emission nebula in the constellation Orion ::
::data[format=table title="Infobox nebula"]
| Field | Value |
|---|---|
| name | IC 434 |
| image | Barnard 33.jpg |
| image_scale | 1.3 |
| caption | IC 434 is found behind the Horsehead Nebula |
| credit | |
| type | emission |
| type2 | |
| epoch | J2000 |
| subtype | H II region |
| constellation | Orion |
| ra | |
| dec | |
| dist_ly | 385 pc |
| appmag_v | 4.5 |
| appdia | |
| size_v | |
| :: |
| name = IC 434 | image = Barnard 33.jpg | image_scale = 1.3 | alt = | caption = IC 434 is found behind the Horsehead Nebula | credit = | type = emission | type2 = | epoch = J2000 | subtype = H II region | class = | constellation = Orion | ra = | dec = | dist_ly = 385 pc | dist_pc = | dist_z = | appmag_v = 4.5 | appdia = | size_v = | radius_ly = | radius_pc = | dimensions = | absmag_v = | notes = | names =
IC 434 is a bright emission nebula in the equatorial constellation of Orion. It was discovered on February 1, 1786, by German-British astronomer William Herschel. The nebula is located at a distance of approximately 385 pc from the Sun and spans the interior of a neutral hydrogen shell with an angular size of . At that distance, the dimensions correspond to a projected size of 13 ×.
This is an H II region that is being ionized by ultraviolet radiation from the nearby Sigma Orionis (σ Ori) multi-star system. An additional half dozen stars provide further illumination of IC 434. This H II region is one of the youngest to form around members of the Orion OB1 association of hot stars. The region has a radius of about 4 pc and a mass of around The mass displaced by the advancing ionization front of IC 434 is estimated at . The nebula includes dust with an estimated mass of .
IC 434 is surrounded by a shell of neutral hydrogen gas with the identifier GS206-17+13. The primary driving energy behind this expanding shell was likely supplied by the blue supergiant Epsilon Orionis. The Horsehead Nebula is a dark nebula that is silhouetted against the diffuse background of IC 434. It is protruding from the Orion B molecular cloud, which is part of the Orion molecular cloud complex.
References
| title=Kinematics of the Horsehead Nebula and IC 434 Ionization Front in CO and C+ | last1=Bally | first1=John | last2=Chambers | first2=Ed | last3=Guzman | first3=Viviana | last4=Keto | first4=Eric | last5=Mookerjea | first5=Bhaswati | last6=Sandell | first6=Goran | last7=Stanke | first7=Thomas | last8=Zinnecker | first8=Hans | display-authors=1 | journal=The Astronomical Journal | volume=155 | issue=2 | at=id. 80 | date=February 2018 | doi=10.3847/1538-3881/aaa248 | doi-access=free | bibcode=2018AJ....155...80B }}
| title=A bimodal dust grain distribution in the IC 434 H ii region | last1=Ochsendorf | first1=B. B. | last2=Tielens | first2=A. G. G. M. | journal=Astronomy & Astrophysics | volume=576 | at=id. A2 | date=April 2015 | doi=10.1051/0004-6361/201424799 | arxiv=1501.02256 | bibcode=2015A&A...576A...2O }}
| title=The 100 Best Targets for Astrophotography: A Monthly Guide for CCD Imaging with Amateur Telescopes | first=Ruben | last=Kier | year=2009 | page=31 | publisher=Springer | isbn=978-1-4419-0603-8 | url=https://books.google.com/books?id=fCIYe_NZV08C&pg=PA31 }}
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::