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Upper Sword Cluster

Updated: Jan 23


About this object


NGC 1981, known as the Upper Sword Cluster or the Alligator Cluster, is an open star cluster located in the Orion constellation, near the northern edge of the Orion Nebula (M42). It lies approximately 1,300 light-years away from Earth and is estimated to be around 5 million years old, making it a relatively young cluster in astronomical terms. NGC 1981 contains bright, blue stars that are loosely bound together by gravity, showcasing their recent formation from the same molecular cloud as other nearby stellar objects. Easily visible through binoculars or small telescopes, the cluster provides a striking contrast to the dense nebulosity of the nearby Orion Nebula and serves as a beautiful example of young star clusters unobscured by interstellar dust.


Designations


Standardized Catalogues


PMC Observatory Catalogue


Observations


  1. 2025-01-09 at around 11:30 pm (+00:00)

  2. 2025-01-22 at around 10:30 pm (+00:00)


Location in the sky


The upper star of the Orion sword in the Orion constellation.



Photographs




The cluster can be seen in the middle, while at the top the two stars are 42 and 45 Orionis.
The cluster can be seen in the middle, while at the top the two stars are 42 and 45 Orionis.

Sketch


Below is a sketch showing the Upper Sword Cluster details.

NGC 1981 is an open star cluster located in the constellation Orion, approximately 1,500 light-years from Earth. It contains around 20 stars, primarily of spectral types B and A, indicating that these are young, hot stars. The cluster is situated near the Orion Nebula (M42) and is part of the larger Orion molecular cloud complex. Due to its proximity to the Orion Nebula, NGC 1981 is often observed alongside it, providing a broader view of the stellar nursery. Adjacent to NGC 1981 is the Running Man Nebula (NGC 1977), a reflection nebula that, along with NGC 1975 and NGC 1973, forms part of the Sharpless 279 (Sh2-279) complex. This region is characterized by a combination of emission and reflection nebulae, with the Running Man Nebula being the most prominent - in the sketch and image above slightly visible as a faint nebulosity near KX Ori and HD294262. The Running Man Nebula is often studied to understand the processes of star formation and the interaction between young stars and their surrounding gas and dust. Observing NGC 1981 and the Running Man Nebula together offers a glimpse into the dynamic environment of the Orion molecular cloud complex, where new stars are continually being born. The combination of the young, hot stars in NGC 1981 and the intricate nebular structures provides valuable insights into the processes that govern star formation and the evolution of stellar clusters.
NGC 1981 is an open star cluster located in the constellation Orion, approximately 1,500 light-years from Earth. It contains around 20 stars, primarily of spectral types B and A, indicating that these are young, hot stars. The cluster is situated near the Orion Nebula (M42) and is part of the larger Orion molecular cloud complex. Due to its proximity to the Orion Nebula, NGC 1981 is often observed alongside it, providing a broader view of the stellar nursery. Adjacent to NGC 1981 is the Running Man Nebula (NGC 1977), a reflection nebula that, along with NGC 1975 and NGC 1973, forms part of the Sharpless 279 (Sh2-279) complex. This region is characterized by a combination of emission and reflection nebulae, with the Running Man Nebula being the most prominent - in the sketch and image above slightly visible as a faint nebulosity near KX Ori and HD294262. The Running Man Nebula is often studied to understand the processes of star formation and the interaction between young stars and their surrounding gas and dust. Observing NGC 1981 and the Running Man Nebula together offers a glimpse into the dynamic environment of the Orion molecular cloud complex, where new stars are continually being born. The combination of the young, hot stars in NGC 1981 and the intricate nebular structures provides valuable insights into the processes that govern star formation and the evolution of stellar clusters.

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