NGC 5981 - Draco Triplet
The so-called Draco Triplet is one of the most beautiful galaxy groups in the northern sky. It consists of the galaxies NGC 5981, 5982 and 5985, two of
which (5982/5985) were discovered back in 1788 by F.W. Herschel, while the third galaxy was not discovered until 1850. The distance is given to be
120 to 140 million light-years.
1) NGC 5981: The faintest galaxy in the triplet ( on the right) has an apparent magnitude of 13.2mag and a size of 2.7x0.3'. We see it almost from the side
(EdgeOn). It is a Hubble Type "Sc" spiral galaxy with a true size of 95,000 light-years.
2) NGC 5982 is an elliptical galaxy of type E3 with a diameter of 110,000 light-years. From its apparent brightness of 11.0mag, the absolute magnitude
can be calculated to be M= -22.0mag, which corresponds to a luminosity of 55 billion suns. In its halo, 26 different shells can be recognized, which have
radii between 8" and 150". These were formed during the merger with a smaller elliptical galaxy. At the center of NGC 5982 resides a supermassive black
hole with a mass of 830 million suns.
3) NGC 5985 is a rather large barred spiral type SAB with a diameter of 190,000 light-years. This makes it much larger than our Milky Way or the
Andromeda galaxy. Its apparent magnitude is given as 11.1mag and its size as 5x3'.
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The Draco triplet offers a great view on a dark spring night with a 20" telescope and is also highly recommended for somewhat smaller telescopes. At a
magnification of 270x you can even detect some details in the individual galaxies:
1) NGC 5981: very elongated with an elongation of 7:1, the ends appear pointed and an elongated central area can be seen in the center. However, no
stellar core is visible. A really beautiful edge-on galaxy! :)
2) NGC 5982: Appears bright and slightly oval with a strong increase in brightness towards the middle. There is a bright stellar nucleus in the very center.
3) NGC 5985: also quite bright, the central area is small and harbors a faint sN. The halo appears mottled, but the arms are unfortunately not recognizable.
