NGC 6744 (also known as Caldwell 101) is an impressive spiral galaxy that lies about 30 million light-years away in the southern constellation of Pavo (the Peacock). But this view could almost be a picture postcard of our own Milky Way, taken and sent by an extragalactic friend, as this galaxy closely resembles our own.
We see NGC 6744 almost face-on, meaning we get a dramatic bird’s eye view of the galaxy’s structure. If we had the technology to escape the Milky Way and could look down on it from intergalactic space, this view is close to the one we would see — striking spiral arms wrapping around a dense, elongated nucleus and a dusty disk. There is even a distorted companion galaxy — NGC 6744A, seen here as a smudge to the upper left of NGC 6744, which is reminiscent of one of the Milky Way’s neighboring Magellanic Clouds.
One difference between NGC 6744 and the Milky Way is their size. While our galaxy is roughly 100,000 light-years across, the galaxy pictured here extends to almost twice this diameter. Nevertheless, NGC 6744 gives us a tantalizing sense of how a distant observer might see our own galactic home.
This dramatic object is one of the largest and nearest spiral galaxies. Although it has a brightness of about 60 billion Suns, its light spreads across a large area in the sky — about two-thirds the width of the Full Moon, making the galaxy appear as a hazy glow with a bright center through a small telescope. Still, it is one of the most beautiful objects in the southern sky, and it can be identified by amateur astronomers as an oval shape contrasting with a rich background of stars (text adapted from astronomy.com).
Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (330m) L (580m) R (180m) G (150m) B (190m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
Many galaxies are visible in the field of view of this cosmic vista and three are particular noteworthy. M49, at right in the image above, was the first member of the Virgo Cluster of galaxies to be discovered by Charles Messier in 1771. With a magnitude of 8.3 and located about 50 million light-years away in the constellation of Virgo, M49 is supposed to have a supermassive black hole in its nucleus with an estimated mass 565 million times the mass of the Sun. This galaxy has a large collection of globular clusters, estimated at about 5,900. Barely visible around M49 is a faint extended, interleaved shell system reminiscent of the radial accretion of a satellite companion, discovered only in 2010.
NGC4526, at left in the image above, is a lenticular galaxy with a magnitude of 9.6, located in between two relatively bright stars that makes it an easy target to be spotted visually. NGC 4535 is the bright spiral galaxy above NGC 4526. It was discovered in 1785 by William Herschel that described it as an easy object and at 9.8 has a similar magnitude of the latter. Due to the relative brightness and close location to M49, it is surprising how Messier missed these two galaxies, hence the nicknames of "lost galaxies".
Apo TEC140 (140/f7.2) - FLI Proline 16803 - L (540m) R (130m) G (130m) B (120m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two and a half million light-years away. But without a telescope, even this immense spiral galaxy - spanning over 200,000 light years - appears as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this telescopic digital image. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept less than 90 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe (text adapted from APOD).
TEC 140APO & AP Mach1 - FLI Proline 16803 - Ha (180m) L (150m) R (45m) G (45m) B (45m) - Gambugliano, Vicenza, Italy