Tau Canis Majoris Cluster, Mexican Jumping Star
|Right Ascension||07 : 18.8 (h:m)
|Declination||-24 : 57 (deg:m)
|Visual Brightness||4.1 (mag)
|Apparent Dimension||8 (arc min)|
Discovered by Hodierna before 1654.
The Tau Canis Majoris cluster, NGC 2362, was one of the discoveries of Hodierna which he published in 1654. Nevertheless, as these observations were forgotten until their rediscovery in the early 1980s, this cluster escaped its rediscovery until it was eventually found and cataloged by William Herschel.
Open cluster NGC 2362 contains about 60 stars, and with 25 million years, is quite young; it is still associated with nebulosity. The brightest star is Tau Canis Majoris, which is of magnitude 4.39 and spectral type O8 (Sky Catalog 2000). As it is the brighter component of a a spectroscopic binary, the mass of the system could be estimated at 40 to 50 solar masses. If, as it appears, this star is actually a member of this cluster at 5,000 light years distance, it is one of the most luminous supergiants known, at about absolute magnitude -7, or 50,000 solar luminosities.
The Sky Catalog 2000 classified this cluster as of Trumpler type I,3,p,n, taking into account that it is associated with a huge but faint diffuse nebula, which is 1.5 x 5 degrees in extension ! However, Burnham states that there's no nebulosity in the immediate neighborhood; this may be blown away by the enormous stellar wind of the young stars, above all Tau CMa.
NGC 2362 is mentioned with the emission nebula NGC 2359 (No. 34) in the RASC Finest NGC Objects List. Caldwell 64.
Last Modification: 29 Mar 1998, 13:00 MET