NGC 5899 in Bootes

June 2021 - Galaxy of the Month

This interactive image of the NGC 5899 and was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We also have a finder chart should help you locate these galaxies, as will this link for NGC 5899 on the Stellarium Web planetarium.

It seems in some ways pointless to do a galaxy of the month for June and July from here in the UK as it never really gets dark enough to chase galaxies down, unless they are really bright. However, for the sake of completeness I have chosen the bright spiral galaxy NGC 5899 in Bootes for this month’s challenge.

NGC 5899 appears to be in a non-interacting pair with the much fainter NGC 5900 according to the RC2, however recent deep images of the pair suggest there are tidal tails coming off NGC 5900 and the dust lane in NGC 5900 also appears warped which suggests that a gravitational interaction is taking place between the pair.

Both of these galaxies were discovered by William Herschel in 1787, although not in the same sweep. Mitchell observing with Lord Rosse’s 72” at Birr believed he found another two nebulae near NGC 5900 although the one catalogued as NGC 5901 turned out to be just a star. The field also contains the much fainter and unrelated galaxies NGC 5893, NGC 5895 and NGC 5896.

If the distance measurements are correct NGC 5899 is about 46Mpc away. NGC 5899 appears to be a spiral galaxy seen at a highly inclined angle and has been given the rather complex morphological classification of SAB(rs)c which suggests it has a ring from which the spiral arms start. NGC 5900 is also a spiral but in this case seen almost edge on with a strong dust lane. NGC 5899 has also been classified as a Type 2 Seyfert galaxy which suggests it has an AGN. The UV images from GALEX show bright star forming regions in its spiral arms. The tidal tail in NGC 5900 also seems to show some UV emission.

Visually observing the field is complicated by the existence of the 6th magnitude star SAO 45445 close to the galaxies and a high-power eyepiece maybe needed to keep it out of the field when observing the galaxies. UK observations suggest that NGC 5899 can be seen faintly with a 25cm scope, although the same observer did not record an observation of NGC 5900 which suggests it is fainter. If you find NGC 5899 and NGC 5900 too easy then try for the fainter trio around NGC 5893 the other side of the star. Although NGC 5899 does not make the Herschel 400 list it does make the H400 II list. Steve Gottlieb’s observations of the field (along with all other NGC objects) can be found on his website.

Owen Brazell - Galaxy Section Director