Remarkably, in the last 6 years two Type II supernovae, representing the death explosions of massive stars, have been detected in nearby spiral M51. Along with a third supernova seen in 1994, that amounts to a supernova bonanza for a single galaxy. As demonstrated in these comparison images, SN2005cs, the supernova discovered in 2005, and more recently SN2011dh, the exceptionally bright supernova first recorded just last month, both lie along M51's grand spiral arms.
National Aeronautics and Space Administrations (NASA) hubble space telescope captured two dramatically different face-on views of the spiral galaxy Messier 51 or M51, dubbed the Whirlpool Galaxy. Researchers constructed the image by combining visible-light exposures from Jan. 18 to 22, 2005, with the Advanced Camera for Surveys (ACS), and pictures taken in December 2005 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). The Whirlpool Galaxy is located at a distance of about 30 million light-years from the Milky Way Galaxy in the constellation Canes Venatici, which is one of the 88 official modern constellations. A constellation is an internationally defined area of the celestial sphere. Read more
Title: A Catalogue of Bright Star Clusters in the Interacting Galaxy M51 Authors: Narae Hwang, Myung Gyoon Lee (Seoul National University, Korea)
We present a catalogue of star clusters with V_{F555W}<23 mag detected in the interacting spiral galaxy M51 system based on the mosaic images taken with HST ACS by the Hubble Heritage Team. We have selected about 3,600 clusters based on their morphological information through the visual inspection. The final star cluster catalogue includes 2,224 clusters that are relatively well isolated and have a circular shape. The star clusters in M51 are mostly distributed around the spiral arms of NGC 5194. The colour-magnitude diagrams show that most of the star clusters in M51 are bluer than (B_{F435W}-V_{F555W}) = 0.5 and (V_{F555W}-I_{F814W}) = 0.8. There are also some red star clusters with (B_{F435W}-V_{F555W}) > 0.7, uniformly distributed over the M51 field. Some of these red clusters are suspected to be a part of the halo or old disk population based on their old ages (t >= 10^9 yrs) and their spatial distribution. The luminosity function of the star clusters is fit well by a single power law with \alpha = -2.59 \pm 0.03 for the range -10.0 <M_V < -8.0 mag. We find that the size distribution of the star clusters can be fit with three Gaussian components with peaks at effective radii of 2.27, 4.80 and 7.51 pc. Some large star clusters with red colour are faint fuzzy clusters, and they are distributed not only around NGC 5195 but also around NGC 5194. These faint fuzzies are found to display an elongated spatial distribution, while the normal compact red clusters show a relatively uniform distribution around NGC 5194.
Position (J2000): RA 13h 29m 55.7s | Dec +47° 13' 53
M51, whose name comes from being the 51st entry in Charles Messier's catalogue, is considered to be one of the classic examples of a spiral galaxy. At a distance of about 30 million light years from Earth, it is also one of the brightest spirals in the night sky. A composite image of M51, also known as the Whirlpool Galaxy, shows the majesty of its structure in a dramatic new way through several of NASA's orbiting observatories. X-ray data from NASA's Chandra X-ray Observatory reveals point-like sources (purple) that are black holes and neutron stars in binary star systems. Chandra also detects a diffuse glow of hot gas that permeates the space between the stars. Optical data from the Hubble Space Telescope (green) and infrared emission from the Spitzer Space Telescope (red) both highlight long lanes in the spiral arms that consist of stars and gas laced with dust. A view of M51 with the GALEX telescope shows hot, young stars that produce lots of ultraviolet energy (blue).