UGC 2885 - GIANT SIZE Spiral Galaxy

          

 Type Sc  Spiral Galaxy in Perseus

   RA = 3h 53.5m 2.5s    DEC = +35 35' 18''  Distance ~ 96  Mpc   Diameter ~ 250 kpc

   m  =  +13.5  Apparent size = 5.5'

   Mass = 2  x 1012  M    (Milky Way = 5  x 1011 M )   Redshift = 5,800 km/sec, not unusual

 

The spiral galaxy UGC 2885 is the largest known spiral galaxy being some 250,000 parsecs in size (815,000 light years). It is some 10 times larger than the Milky Way !  The diagram below shows the comparison of UGC 2885's size vs. some other well known galaxies.

                 

               In the comparison diagram above, galaxy diameters are given in kilo-parsecs (kpc).

UGC 2885 is located in the constellation Perseus. It is located  less than 1 degree from the famous California Nebula, and 10 degrees north of the Pleiades. Its rotation period is nearly 2 billion years at a distance of 125,000 parsecs from the nucleus. Therefore the outer regions have undergone just 7 revolutions since the origin of the Universe. The Milky Way by comparison has rotated some 50 times since the origin of the known Universe.  Yet with so few rotations, the spiral arms are smooth and well developed. No large scale velocity irregularities exist.

 Large scale velocity regularity coupled with so few rotations means that a well-ordered global spiral pattern must have been established soon after galaxy formation. It cannot be the product of smoothing after many rotations. Hence large disk galaxies with global spiral patterns such as UGC 2885 put important constraints on models of galaxy  formation and evolution.

          

UGC Finder Chart. Its just 1 degree south of the California Nebula and 10 degrees north of M45, the Pleiades cluster.

 

References:

Canzian, B. Allen, R.J., Tilanus, R.P.J., 1993, Spiral Structure of the Giant Galaxy UGC 2885: Hά Kinematics, Astrophysical Journal, 406, p. 457.

Canzian, B., 1993, Co-rotation Resonance: UGC 2885 and a New Method, Publications of the Astronomical Society of the Pacific, 105, p. 661.

Rubin, V., 1997, Bright Galaxies Dark Matters, AIP Press, Woodbury, NY, p. 47. ISBN 1-56396-231-4