The Spindle Galaxy, a lenticular galaxy in Draco

read more at Anne’s Astronomy News http://annesastronomynews.com/

October 1, 2012

Image Credit: W. Keel (U. Alabama), NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

The Spindle Galaxy (designated NGC 5866 and M102) is a relatively bright lenticular galaxy of about 69,000 light-years across, located some 44 million light-years away in the northern constellation of Draco. The galaxy is moving away from us at 672 kilometers per second.

The Spindle is one of the brightest galaxies in the NGC 5866 Group, a small galaxy group that also includes the spiral galaxy NGC 5907 (Splinter Galaxy). Its mass is estimated to be about 1 trillion solar masses, so it is a considerably massive galaxy. No supernovae have been discovered in this galaxy yet.

The galaxy — which appears very flat because it is seen exactly edge-on — has a transparent outer halo, and numerous and complex dark dust lanes, but the many bright stars in the disk give it a blue underlying hue. The bulge in the center of the disk appears reddish from the older and redder stars that likely exist there. This bulge is surrounding a bright nucleus.

The blue disk of young stars running parallel to the dust lane, extends well beyond the dust disk in the extremely thin galactic plane. This means that dust and gas, still in the galaxy and potentially available to form stars, does not stretch nearly as far out in the disk as it did when most of these stars in the disk were formed.

The dust lane is slightly warped compared to the disk of starlight. This warp indicates that NGC 5866 may have undergone a gravitational tidal disturbance in the distant past, by a close encounter with another galaxy of the NGC 5866 group of galaxies.

Numerous filaments of dust can be seen meandering away from the disk of the galaxy out into the bulge and inner halo of the galaxy. These are short-lived on an astronomical scale, since clouds of dust and gas will lose energy to collisions among themselves and collapse to a thin, flat disk.

The outer halo is dotted with numerous gravitationally bound clusters of nearly a million stars each, known as globular clusters. Background galaxies that are millions to billions of light-years farther away than NGC 5866 are also seen through the halo.

(NGC 3115 is another lenticular galaxy referred to as the Spindle Galaxy.)

This image is taken with the Hubble Space Telescope.

n/a