Young blue stars circling the galactic center dominate the Andromeda Galaxy in this image taken in ultraviolet! About 2.5 million light-years away, the Andromeda Galaxy, also known as M31, really is our galactic neighbour. Spanning about 230,000 light-years, it took 11 different image fields from NASA’s Galaxy Evolution Explorer (GALEX) satellite telescope to produce this gorgeous portrait of the spiral galaxy in ultraviolet light in 2003. Its spiral arms stand out in visible light images, Andromeda’s arms are sites of intense star formation. They have been interpreted as evidence that Andromeda collided with its smaller neighboring elliptical galaxy M32 more than 200 million years ago. The Andromeda galaxy and our own comparable Milky Way galaxy are the most massive members of the Local Group of galaxies and are projected to collide in several billion years – perhaps around the time that our Sun’s atmosphere will expand to engulf the Earth.
This bundle of bright stars and dark dust is a dwarf spiral galaxy known as NGC 4605, located around 16 million light-years away in the constellation of Ursa Major (The Great Bear). This galaxy’s spiral structure is not obvious from this image, but NGC 4605 is classified as an SBc type galaxy — meaning that it has sprawling, loosely wound arms and a bright bar of stars cutting through its centre. NGC 4605 is a member of the Messier 81 group of galaxies, a gathering of bright galaxies including its namesake Messier 81, and the well-known Messier 82. Galaxy groups like this usually contain around 50 galaxies, all loosely bound together by gravity. This group is famous for its unusual members, many of which formed from collisions between galaxies. With its somewhat unusual form, NGC 4605 fits in well with the family of perturbed galaxies in the M81 group, although the origin of its abnormal features is not yet clear. The Messier 81 group is one of the nearest groups to our own, the Local Group, which houses the Milky Way and some of its well-known neighbours, including the Andromeda Galaxy and the Magellanic Clouds. Galaxy groups provide environments where galaxies can evolve through interactions like collisions and mergers. These galaxy groups are then lumped together into even larger gatherings of galaxies known as clusters and superclusters. The Local and Messier 81 groups both belong to the Virgo Supercluster, a large and massive collection of some 100 galaxy groups and clusters. With so many galaxies swarming around, NGC 4605 may seem unremarkable. However, astronomers are using this galaxy to test our knowledge of stellar evolution. The newly-formed stars in NGC 4605 are being used to investigate how interactions between galaxies affect the formation, evolution, and behaviour of the stars within, how bright stellar nurseries come together to form stellar clusters and stellar associations, and how these stars evolve over time. And that’s not all — NGC 4605 is also proving to be a good testing ground for dark matter. Our theories on this hypothetical type of matter have had good success at describing how the Universe looks and behaves on a large scale — for example at the galaxy supercluster level — but when looking at individual galaxies, they have run into problems. Observations of NGC 4605 show that the way in which dark matter is spread throughout its halo is not quite as these models predict. While intriguing, observations in this area are still inconclusive, leaving astronomers to ponder over the contents of the Universe. Caption: Hubble Heritage Team
ESA/HUBBLE & NASA ACKNOWLEDGEMENT: D. CALZETTI (UNIVERSITY OF MASSACHUSETTS) AND THE LEGUS TEAM
Spectacular image of the spiral galaxy NGC 7331 captured by the Hubble Space Telescope. It’s located around 45 million light-years from Earth, residing in the constellation Pegasus.
I don’t know about you, but this is one of the sexiest pictures of a galaxy I’ve ever seen. This galaxy knows it’s fine af—showing off its lovely and colorful swirling arms. Fuck me.
This remarkable spiral galaxy, known as NGC 4651, may look serene and peaceful as it swirls in the vast, silent emptiness of space, but don’t be fooled - it keeps a violent secret. It is believed that this galaxy consumed another smaller galaxy to become the large and beautiful spiral that we observe today.
Although only a telescope like the NASA/ESA Hubble Space Telescope, which captured this image, could give us a picture this clear, NGC 4651 can also be observed with an amateur telescope - so if you have a telescope at home and a star-gazing eye, look out for this glittering carnivorous spiral.
What’s happening in the center of nearby spiral galaxy M77? The face-on galaxy lies a mere 47 million light-years away toward the constellation of the Sea Monster (Cetus). At that estimated distance, this gorgeous island universe is about 100 thousand light-years across. Also known as NGC 1068, its compact and very bright core is well studied by astronomers exploring the mysteries of supermassive black holes in active Seyfert galaxies. M77 and its active core glows bright at x-ray, ultraviolet, visible, infrared, and radio wavelengths. The featured sharp image of M77 was taken by the Hubble Space Telescope and is dominated by the (visible) red light emitted by hydrogen. The image shows details of the spiral's winding spiral arms as traced by obscuring dust clouds, and red-tinted star forming regions close in to the galaxy’s luminous core.
Why does this galaxy spin so fast? To start, even identifying which type of galaxy UGC 12591 is difficult – featured on the lower left, it has dark dust lanes like a spiral galaxy but a large diffuse bulge of stars like a lenticular. Surprisingly observations show that UGC 12591 spins at about 480 km/sec, almost twice as fast as our Milky Way, and the fastest rotation rate yet measured. The mass needed to hold together a galaxy spinning this fast is several times the mass of our Milky Way Galaxy. Progenitor scenarios for UGC 12591 include slow growth by accreting ambient matter, or rapid growth through a recent galaxy collision or collisions – future observations may tell. The light we see today from UGC 12591 left about 400 million years ago, when trees were first developing on Earth.
Image Credit: NASA, ESA, Hubble; Processing & Copyright: Leo Shatz
