Star Clusters and Nebulae: Overview

Introduction

Galaxies3D explores stars clusters and nebulae in our Milky Way galaxy by looking at:

  • Messier objects (= bright extended celestial objects cataloged by Charles Messier in the late 1700's during his searches for comets) and Caldwell objects (= Patrick Moore's catalog of similar bright extended objects. The Caldwell catalog includes celestial objects in the Southern Hemisphere inaccessible to Messier) in the Milky Way,
  • famous — that is, named — star clusters, diffuse nebulae, planetary nebulae, and supernova remnants — most of them in Messier's catalog and the Caldwell catalog.
  • globular clusters, living within the Milky's Way's halo, visible from hundreds of thouands of light years away.
  • clusters and regions of young, newly formed stars that help define our galaxy's spiral arms -- OB Associations, and the most luminous star forming complexes.

As it does in its views on the bright stars, in displaying views of star clusters and nebulae, Galaxies3D makes extensive use of this image of the Milky Way Galaxy by Robert Hurt of NASA and JPL-Caltech, presented at the 212th American Astronomical Society meeting:

Milky Way Galaxy Annotated

Milky Way Galaxy by Robert Hurt of NASA and JPL-Caltech, based on data from the Spitzer Space Telescope. The small circle marking the Sun has a radius of about 750 light years.



We use this Milky Way image to help make clear:

  • the particular patch of the Milky Way's vast expanse we are viewing, and
  • the spiral arm a particular object lies within.


 

Messier's List of Celestal Objects

The Messier objects that lie within our Milky Way galaxy include:

  • diffuse nebulae,
  • planetary nebulae,
  • supernova remnants,
  • open star clusters, and
  • globular star clusters.

In the following view of the Messier objects in our galaxy, you can see that the diffuse nebulae, planetary nebulae, supernova remnants and open star clusters all lie in a small region of the galaxy near the Sun. In contrast, the Messier globular clusters — colored red — span the breadth of the galaxy, from Messier 79 beyond the farthest spiral arm on our side of the galaxy, to Messier 54 beyond the farthest spiral arm on the other side of the galaxy:

Messier Objects in the Milky Way

The actual galactic plane is the grid above the base grid. Messier globular clusters are labeled.

The view below shows all the Messier objects in our Milky Way Galaxy, excluding the globular clusters. The Messier diffuse nebulae, planetary nebulae, supernova remnants, open star clusters lie:

  • within our own Orion Spur spiral arm, or
  • in the section of the Sagittarius spiral arm just in front of us, or
  • in the section of the Perseus arm lying right behind us.

The base grid of this image measures 16.3 kly x 16.3 kly, a small fraction of the breadth of the entire Milky Way. It is worth noting however, that the entire Large Magellanic Cloud, a magellanic spiral galaxy and the largest satellite galaxy of the Milky Way's Subgroup of Galaxies, has a diameter of 14 kly, and would nicely fit within this grid.

Messier Objects in the Milky Way, excluding Globular Clusters

All Messier objects in the Milky Way other than globular clusters



 

Famous Diffuse Nebulae, Planetary Nebulae, Supernova Remants and Open Star Clusters

Famous, — that is, named — diffuse nebulae, planetary nebulae, supernova remnants, open star clusters explored by Galaxies3D draw from both Messier's catalog and Patrick Moore's Caldwell catalog. In the views below, you can see that they also lie in our immediate region of the galaxy:

  • within our own Orion Spur spiral arm, or
  • in the section of the Sagittarius spiral arm just in front of us, or
  • in the section of the Perseus arm lying right behind us.

Famous Diffuse and Dark Nebulae:

Famous Diffuse and Dark Nebulae

Famous Diffuse and Dark Nebulae



Famous Open Clusters:

Famous Open Clusters

Famous Open Clusters



Famous Open Clusters Within 2900 Light Years:

Famous Open Clusters Within 2900 Light Years

Famous Open Clusters Within 2900 Light Years



Famous Planetary Nebulae and Supernova Remnants:

Famous Planetary Nebulae and Supernova Remnants

Famous Planetary Nebulae and Supernova Remnants



 

Young, Bright Star Forming Regions

OB Associations (associations of young, bright O and B stars), and complexes of young massive stars mark and highlight a galaxy's spiral arms. This is a view of the nearby Milky Way OB associations, by Melnik et al, Astronomy Letters 21, pp 10-26, 1995:

Here is view of the most luminous massive young star-forming complexes, cataloged by Urquhart et al, MNRAS 437, 1791-1807, 2014 (full dataset retrieved from VizieR Astronomical Server):

 

Globular Clusters

Globular clusters live in the halo of our galaxy, roaming far beyond and above the spiral arms and visible disk of the Milky Way. The following is a view of the known 157 globular clusters of the Milky Way. Note that the second grid lying above the base grid is the actual plane where the disc and spiral arms of the Milky Way live. The image of the Milky Way seen on the lower, base grid is actually being projected down from the upper grid to the lower, base grid. The outermost globular clusters — those farthest from the galactic center — are labeled:

Here is a view of globular clusters within 100,000 light years (100 kly) of the galactic center. Globular clusters farther than 25,000 light years of the galactic center are labeled:

Here is a view of the globular clusters with 25,000 light years of the galactic center — closer to the galactic center than the Sun:

 

Star Clusters and Nebulae