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M25

Messier 25
Open Star Cluster
Right Ascension 18h 31m 36s Best Seen 8/1-10/15
Declination -19° 15' 00" Magnitude 6.5
Constellation Sagittarius

Actual		 Compared
to Sun
Distance 2,000 ly --
Diameter ~ 23 ly --
Number of Stars 86 1
Actual Brightness -- --
Age 90 million years 5 billion
Integrated Spectral Type -- G2 V
Density (gram/cubic cm) -- --

What To Look For Through The Telescope

  1. Recommended eyepiece: 40mm or 80mm.

  2. Through the telescope the cluster will appear as a group of individual stars.

M25 Information

  1. The most luminous stars in this cluster are of spectral type B4.

  2. It also has about 50 stars which are brighter than 12th magnitude.

  3. These stars formed from a portion of the Lagoon Nebulae.

  4. This cluster was discovered in 1745-6 by Philippe Loys de Chéseaux.

  5. This cluster contains a Cepheid variable star.

    a. A Cepheid star varies in brightness over a period of days.

    b. The amount of change of brightness and the period are directly related, and can be used to find a fairly accurate distance to the star.

    c. If a Cepheid is found in a cluster or a galaxy, the distance to that cluster or galaxy can be determined.
Home > Star Clusters > Open > M25 > Reference top
References
Item Updated Notes
Coordinates 2002-12-10 tweaked with SIMBAD and http://www.seds.org/messier/m/m025.html
Magnitude 2002-12-10 OK with http://www.seds.org/messier/m/m025.html
Distance 2002-12-10 OK with http://www.seds.org/messier/m/m025.html
Actual Brightness --
Number of Stars 2002-12-10 OK with http://www.seds.org/messier/m/m025.html
Diameter 2002-12-10 OK with http://www.seds.org/messier/m/m025.html
Age 2002-12-10 OK with http://www.seds.org/messier/m/m025.html
Integrated Spectral Type --
Other Information 2002-12-10 Cannot find any supporting evidence for items 1-3
Items 4 and 5 are from http://www.seds.org/messier/m/m025.html