NGC 2264

Starforming Nebula and Open Cluster NGC 2264 (= H V.27 (Nebula) = H VIII.5 (Cluster), = h 401 = GC 1440), type 'c', in Monoceros

The Cone Nebula and the Chrismas Tree Cluster
Cone Nebula: H V.27; Chrismas Tree Cluster: H VIII.5, 15 Mon Cl, Mel 49, Cr 112.

[NGC 2264, Cone Nebula, AAT]
Right Ascension 06 : 41.1 (h:m)
Declination +09 : 53 (deg:m)
Distance 2.3 (kly)
Visual Brightnes 3.9 (mag)
Apparent Dimension 20.0 (arc min)

William Herschel discovered the cluster in 1781, the nebula in 1785.

The Chrismas Tree Cluster and the Cone Nebula were both discovered by William Herschel. He found the cluster first on February 15, 1781 with a 6.2-inch reflector before having started to compile his catalog. After starting his systematic survey with his 18.7-inch reflector, he found it again on January 18, 1784, and cataloged it as H VIII.5. He also discovered the nebula on December 26, 1785, and assigned it the catalog number H V.27.

The nebula belongs to a much larger complex, which is currently an active star forming region. The open cluster was estimated at a considerably young age of only 9 million years, and classified as of Shapley class "c" (loose and irregular) and of Trumpler type "IV,3,pn" (not well detached from star field, stars of large brightness range, poor - less than 50 stars). Meanwhile, about 250 stars have been classified as member stars, so that the old Trumpler classification as "poor" is outdated. Modern measurement of the parallax of the cluster stars has given a value of about 2,300 light-years for the distance of both cluster and nebula.

The brightest star in the nebula shown in our image is HD 47887 of visual magnitude 7.14.

[NGC 2264 cluster, AAT] The brightest star in the cluster - outside our primary image but in our larger field image, is the Be star 15 Monocerotis (15 Mon, or S Mon). It is a spectroscopic binary (type SB2) with primary (15 Mon Aa) of spectral type O7 V((f))z, and secondary (15 Mon Ab) of B1: Vn. The primary is the main ionizing source that excitates the nebula. In addition, it is an irregular variable with small amplitude 0.07 mag. The system has an orbital period of about 74 years (still uncertain). Total visual brightness varies between about m_v = 6.42 and 6.48 mag. (Trigueros Páez et.al. 2021). This system is part of a visual double star, component B is of spectral type B1.5/2 V and mag m_v = 7.83.

Our images have been obtained by David Malin with the Anglo-Australian Telescope. These images are copyrighted by the Australian Astronomical Observatory; see their usage policy.

  • More information on the primary image (Cone Nebula, by David Malin)
  • More on the AAT image of cluster NGC 2264 and S Monocerotis region (also by David Malin)

    The Hubble Space Telescope was used in 1997 to obtain images of forming stars in the Cone Nebula.

    In the John Caldwell's observing list and the Astronomical League's Deep Sky Binocular Club list.

  • Jean-Claude Mermilliod's WEBDA cluster page for NGC 2264
  • SIMBAD Data of NGC 2264
  • Publications on NGC 2264 (NASA ADS)
  • Observing Reports for NGC 2264 (IAAC Netastrocatalog)
  • NGC Online data for NGC 2264

  • Wikipedia page for NGC 2264

    Reference


    Hartmut Frommert
    Christine Kronberg
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    Last Modification: July 26, 2026
    Former Definitive Version: May 20, 2006