α Sextantis

Alpha Sextantis is only a 4.5 visual magnitude star, but even so it's the brightest star in this constellation.

The star is twelve degrees due south of Regulus (alpha Leonis). If you centre Regulus in your glasses and move south three fields of vision, alpha Sextantis will be toward the northern part of your field of view.

Alpha Sextantis is classified as a white giant, about 3.8 times the Sun's radius, and about 300 million years old. Its future is much brighter, as it will grow into an orange giant in just another 50 or 60 million years.


A little more than a binocular field south are twin stars 17 and 18 Sextantis; 2 northwest of them is the bright galaxy NGC 3115: binoculars.
      Often called the Spindle Galaxy because of its shape, the proper description would be a lenticular galaxy, for the galaxy (seen on edge), appears as a white glow with a bulge in the centre. It has an apparent magnitude of 9.7.
      The galaxy has a black hole at its centre with a mass of about two billion solar masses, the closest of its kind to the solar system.

If you place epsilon Sextantis (in the same field) on the eastern edge, then move one field westward, gamma Sextantis becomes visible. This is a multiple system (h4256):
      AB: 5.4, 6.4; 49, 0.5" with an orbit of 77.55 years.
      AB-C: 5.1, 12.3; 333, 36.9".

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1999-2014 by Richard Dibon-Smith.