"In the Andromeda galaxy we have the unique combination of a global yet detailed view of a galaxy similar to our own. We have lots of detail in our own Milky Way, but not the global, external perspective," said study co-author Prof Puragra Guhathakurta of the University of California, Santa Cruz. ...
"The comparison to the Milky Way revealed substantial differences suggesting that Andromeda has had a more violent accretion history in the recent past. Even the most well ordered Andromeda stars are not as well ordered as the stars in the Milky Way's disk."
What's happening at the center of spiral galaxy M106? A swirling disk of stars and gas, M106's appearance is dominated by blue spiral arms and red dust lanes near the nucleus, as shown in the featured image. The core of M106 glows brightly in radio waves and X-rays where twin jets have been found running the length of the galaxy. An unusual central glow makesM106 one of the closest examples of the Seyfert class of galaxies, where vast amounts of glowing gas are thought to be falling into a central massive black hole. M106, also designated NGC4258, is a relatively close 23.5 million light years away, spans 60 thousand light years across, and can be seen with a small telescope towards the constellation of the Hunting Dogs (Canes Venatici).
The galaxy has a diameter of around 100,000 light years, making it about the size of the Milky Way. Notably, six observed supernovae exist within Messier 61, placing it in a group of galaxies which includes Messier 83, also with six supernovae observed, and NGC 6946, having nine observed supernovae. Messier 61 makes up part of the Virgo Galaxy Cluster, a massive group of galaxies in the constellation of Virgo (the Virgin).
The Milky Way is smaller than astronomers previously thought, according to new research. For the first time, scientists have been able to precisely measure the mass of the galaxy that contains our solar system. Researchers have found that the Milky Way is approximately half the weight of ou neighboring galaxy – Andromeda – which has a similar structure to our own. The Milky Way and Andromeda are the two largest in a region of galaxies which astronomers call the Local Group.
In this new study, researchers were also able to work out the mass of invisible matter found in the outer regions of both galaxies, and reveal their total weights. They say 90 per cent of both galaxies' matter is invisible. Scientists say that Andromeda's extra weight must be present in the form of dark matter, the little-understood invisible substance which makes up most of the outer regions of galaxies. They estimate that Andromeda contains twice as much dark matter as the Milky Way, causing it to be twice as heavy.
Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. The effect is further enhanced in this sharp image from a small telescope by galaxies that lie beyond the gorgeous island universe.