Messier 74
Messier 74 is a large spiral galaxy in the equatorial constellation Pisces. It is about 32 million light-years away from Earth. The galaxy contains two clearly defined spiral arms and is therefore used as an archetypal example of a grand design spiral galaxy. The galaxy's low surface brightness makes it the most difficult Messier object for amateur astronomers to observe. Its relatively large angular size and the galaxy's face-on orientation make it an ideal object for professional astronomers who want to study spiral arm structure and spiral density waves. It is estimated that M74 hosts about 100 billion stars.
Observation history
M74 was discovered by Pierre Méchain in 1780. He then communicated his discovery to Charles Messier, who listed the galaxy as M74 in his catalog of permanent celestial objects that should not be confused with transient objects in the sky. In July 2022, it was observed by the James Webb Space Telescope.Structure
M74 has two spiral arms that wind counterclockwise from the galaxy's center. The spiral arms widen as they get farther from M74's center, but one of the arms narrows at the end. The arms deviate slightly from a constant angle.Supernovae
Three supernovae have been observed in M74:- SN 2002ap was discovered by Yoji Hirose on 29 January 2002. It was one of few Type Ic supernovae recorded within 10 Mpc every century. This explosion has been used to test theories on the origins of others further away and theories on the emission by supernovae of gamma ray bursts. It got as bright as magnitude 12.3, making it the brightest supernova of 2002.
- SN 2003gd was discovered by Robert Evans on 12 June 2003. Type II supernovae have known luminosities, so they can be used to accurately measure distances. The distance measured to M74 using SN 2003gd is 9.6 ± 2.8 Mpc, or 31 ± 9 million ly. For comparison, distances measured using the brightest supergiants are 7.7 ± 1.7 Mpc and 9.6 ± 2.2 Mpc. Ben Sugerman found a "light echo" - a later reflection of the explosion - associated with SN 2003gd. This is one of the few supernovae in which such a reflection has been found. This reflection appears to be from dust in a sheet-like cloud that lies in front of the supernova, and it can be used to determine the composition of the interstellar dust.
- SN 2013ej was discovered by the Lick Observatory Supernova Search on 25 July 2013. It was bright as 10th magnitude when viewed from the surface of Earth, so it was visible from almost all modern telescopes in a good night sky.
Galaxy group
This is the brightest member of the M74 Group, a group of 5 to 7 galaxies that also includes the peculiar spiral galaxy NGC 660 and a few irregular galaxies. Different group membership identification methods identify several objects of the group in common, and a few galaxies whose exact status within such groupings is currently uncertain.File:M74 3.6 5.8 8.0 microns spitzer.png|thumb|250px|M74 as observed with the Spitzer Space Telescope as part of the Spitzer Infrared Nearby Galaxy Survey. The blue colors represent the 3.6 micrometre emission from stars. The green and red colors represent the 5.8 and 8.0 micrometre emission from polycyclic aromatic hydrocarbons and possibly dust.