[en] [de] [it]

M 64

Spiralna galaksija - Spiral Galaxy M64 (NGC 4826), type Sb, in coma Berenices

Blackeye Galaxy

Rektascenzija 12 : 56.7 (u:m)
Deklinacija +21 : 41 (sto:m)
Razdalja 12000 (*1000 sv.l.)
Vizual. magnituda 8.5 (mag)
Zorni kot 9.3x5.4 (loc min)

M64 is the famous Black Eye galaxy, sometimes also called the ``Sleeping Beauty galaxy". The conspicuous dark structure is a prominent dust feature obscuring the stars behind.

J.D. Wray, in his Color Atlas of Galaxies, points out that M64 may be taken as prototype for a class of galaxies called "ESWAG", for Evolved Second Wave (star forming) Activity Galaxy. As becomes evident in color photos, the main spiral pattern is consisted of an intermediate aged stellar population. Stellar formation has first evolved outside following the density gradient, forming stars as long as there was sufficient interstellar matter available, and then dying out slowly. As the matter was flowing back from the evolved stars, by stellar wind, supernovae, and planetary nebula activity, more and more interstellar matter could accumulate again, so that finally there was enough matter to start the formation of new young stars again. This second wave of star formation has apparently reached now the region where the dark dust lane appears.

The dust feature is well visible even in smaller telescopes. M64 was recently shown to have two counterrotating systems of stars and gas in its disk: The inner part of about 3,000 light years radius is rubbing along the inner edge of the outer disk, which rotates opposite and extends up to at least 40,000 light years, at about 300 km/sec. This rubbing process is probably the reason for the observed vigorous star formation process, which is currently under way, and can be observed as the blue knots imbedded in the peculiar dust lane on one side of the nucleus. It is speculated that this peculiar disk and dust lane may be caused by material from a former companion which has been accreted but has yet to settle into the mean orbital plane of the disk.

The distance of this galaxy seems to be not very well determined. Kenneth Glyn Jones and Mallas/Kreimer give about 12, Tully's Nearby Galaxies Catalog 14 million light years, while Burnham has "20-25" million, and quotes Holmberg with 44 million light years (oddly, this latest value also occurs in Kenneth Glyn Jones' Introduction, p. 7 in the second edition). The radial velocity of 377 km/sec in recession would yield about 16 million light years (H0=75), but this is certainly very inacurate, as the direction to this galaxy is close to the Virgo cluster, so that a considerable deviation from the Hubble law must be taken into account. That the distance is not yet better known is a bit strange, as Cepheid variables in this galaxy should be in the reach of current telescopes, perhaps even the largest Earth-bound ones.

No supernovae have been recorded in this galaxy up to now. It seems that also no Cepheids have, otherwise its distance would be known better.

  • Vec posnetkov M64
  • Amaterski pos. M64

    Povzeto po:
    Hartmut Frommert (spider@seds.org)
    Christine Kronberg (smil@lrz.uni-muenchen.de)

    [SEDS] [MAA] [Home] [M 63] [M 65] [Next Cluster] [Next Nebula] [Next Galaxy] [Image Browser] [DSSM] [Indexes]