Whirlpool Galaxy Galaxy Profile: • Designation: M51, SA(s)bc pec • Type: Spiral • Distance from Milky Way: ~25 million light-years • Diameter: about 75 thousand light-years across • Mass: ~160 billion suns • Number of Stars: > 100 billion\ Facts about the Whirlpool Galaxy: The Whirlpool Galaxy was first discovered in 1773 by Charles Messier, who was charting the skies looking for objects that might be confused with comets. In 1845, astronomer William Parsons observed the galaxy pair with his telescope at Birr Castle, Ireland, and found the spiral structure of the Whirlpool. The Whirlpool and its companion, M51b have already passed by or through each other once as they dance through a cosmic merger. The smaller galaxy has been severely disrupted …show more content…
The whirlpool, like many other galaxies, has a supermassive black hole at its heart, surrounded by rings of dust. The core of the galaxy is quite quite active — making the Whirlpool what astronomers call a “Seyfert galaxy”. The Whirlpool’s companion, called M51b, is a dwarf galaxy. Because it is being torn apart by the ongoing interaction, it cannot be easily classified. Its current appearance makes it look like an irregular galaxy. A bridge of gas and dust ties the two galaxies together as they merge. The Whirlpool Galaxy is a spiral galaxy that is relatively close to Earth — about 30 million light-years away. It is visible in the northern constellation Canes Venatici, just southeast of the Big …show more content…
Skywatchers recorded supernovas in 1994, 2005 and 2011. "Three supernovas in 17 years is a lot for single galaxy, and reasons for the supernova surge in M51 are being debated," noted the NASA website Astronomy Picture of the Day in 2011, without elaborating on the possible explanations. The latest supernova, called SN 2011dh, was at its brightest in June 2011 before slipping back into obscurity. After the event, astronomers scoured older pictures to see if they could find the source of the explosion. They narrowed their search to a yellow supergiant star (visible in Hubble Space Telescope pictures) that was there before the explosion, and appears to be missing afterwards. While most yellow supergiants aren't expected to go supernova when they finish out their lives, the team said it's possible that the star was actually a binary star. The other star would have been a bluer, hotter star that was close enough to pull some of the yellow supergiant's mass away. Given enough time, this would have destabilized the star and caused the explosion, astronomers said. The blue star wasn't spotted in Hubble photos, but astronomers added that it is likely best visible in ultraviolet light — a band of light that Hubble does not look