M 25
OPEN STAR CLUSTER
Right Ascension:
18h 31m 36s
Best Seen:
8/1-10/15
Declination:
-19º 15' 00"
Magnitude:
6.5
Computer File:
m25
Constellation:
Sagittarius
Actual
Compared to
Distance
2,000 l.y.
--
Actual Brightness
--
--
Number of stars
86
--
Diameter
23 l.y.
--
Age
90 million years
--
Integrated Spectral Type
--
--
WHAT TO LOOK FOR THROUGH THE TELESCOPE:
-
Recommended eyepiece: 40mm or 80 mm.
-
Through the telescope the cluster will appear as a group of individual stars.
M 25 INFORMATION:
-
The most luminous stars in this cluster are of spectral type B4.
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It also has about 50 stars which are brighter than 12th magnitude.
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These stars formed from a portion of the Lagoon Nebulae.
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This cluster was discovered in 1745-6 by Philippe Loys de Chéseaux.
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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.
Item
Updated
Notes
Coordinates
12-10-2002
tweaked with SIMBAD and http://www.seds.org/messier/m/m025.html
Magnitude
12-10-2002
OK with http://www.seds.org/messier/m/m025.html
Distance
12-10-2002
OK with http://www.seds.org/messier/m/m025.html
Actual Brightness
Number of Stars
12-10-2002
OK with http://www.seds.org/messier/m/m025.html
Diameter
12-10-2002
OK with http://www.seds.org/messier/m/m025.html
Age
12-10-2002
OK with http://www.seds.org/messier/m/m025.html
Integrated Spectral Type
Other Information
12-10-2002
Cannot find any supporting evidence for items 1-3
Items 4 and 5 are from http://www.seds.org/messier/m/m025.html