|
Designations:
|
NGC 4565, Caldwell C38
|
||
|
Object Type:
|
|||
|
Constellation:
|
Coma Berenices
|
||
|
12 hr 36 min (2000.0)
|
+25° 59 min (2000.0)
|
||
|
9.6
|
Size:
|
16.2 X 2.3 arcminutes
|
|
|
Distance:
|
37 million light years
|
||
|
Discoverer:
|
William Herschel, 1785
|
||
|
In 1855 William Parsons, the third Earl of Rosse, described NGC 4565 as a "beautiful object" after seeing it though his 72-inch reflector. Using that powerful telescope five years earlier, Lorde Rosse had drawn the equatorial dust lane in another edge-on system, NGC 891 (Caldwell 23). At that time he also discovered the spiral nature of some "nebulae" and likened them to nascent planetary systems. The clairvoyant John Herschel, however, had already hinted that extended nebulae were perhaps round nebulae seen edge on. NGC 891, in particular, gave him the impression of a "thin flat ring of enormous dimensions, seen very obliquely." Since there was no reliable way at the time to determine the distances to these nebulae, their true sizes and natures remained a mystery. It wasn't until 1924 that astronomers finally learned that spiral nebulae weren't baby solar systems within our own galaxy but external Milky Ways of their own, scattered throughout a universe whose dimensions humankind was just beginning to grasp. We now know that NGC 4565, like several other Caldwell objects, is a member of the cosmologically local Coma-Sculptor Cloud of galaxies. It is also the largest and most famous edge-on spiral galaxy in the night sky. If we accept its estemated distance of 32 million light-years, this moderately late-type spiral has a true linear diameter of 150,000 light-years and a total mass of 200 billion Suns. Interestingly, the Hubble Space Telescope has identified roughly 200 globular clusters around NGC 4565, a total virtually indistinguishable from that attending our own Milky Way. Recent radio observations have revealed that the galaxy's "rotation curve" - the orbital speed of its disk's constituents, plotted as a function of distance from the nucleus - mimics that of our galaxy; as with or Milky Way, NGC 4565's rotation curve indirectly argues for an extended halo of invisible "dark matter" eveloping the disk. |
|
Telescope:
|
|
|
Focal Length:
|
1200 mm
|
|
Mount:
|
|
|
Camera
|
|
|
Guider:
|
SBIG Remote Guide Head
|
|
Exposures:
|
9 10-minute Luminance exposures and 3 10-minute exposures for each color (R,G,B)
|
|
Location:
|
Cicero, IN
|
|
Software:
|
CCDSoft for image acquisition, processed with CCDStack and Photoshop CS2
|
