NGC 4157
NGC 4157 is a spiral galaxy in the constellation Ursa Major. The galaxy lies about 55 million light years away from Earth, which means, given its apparent dimensions, that NGC 4157 is approximately 125,000 light years across. It was discovered by William Herschel on March 9, 1788.
Characteristics
NGC 4157 seen nearly edge-on, with an inclination of 84° based on CO imaging. The total stellar mass of NGC 4157 is, while the dust mass is estimated to be. The hydrogen disk of NGC 4157 is symmetric and slightly wrapped, indicating no strong interaction with other galaxies, and extends to twice the size of the optical disk. The total HI mass in the galaxy is estimated to be.The star formation rate of the galaxy is per year. A star formation area is visible beyond the end of the optical disk and is also visible in X-ray and ultraviolet imaging. It could probably be the result of a recent accretion.
The galaxy has radio emission extending above and below the optical disk, indicating the presence of a radio halo. There is also radio emission extending southwards from the north-eastern end of the disk.
Supernovae
Three supernovae have been observed in NGC 4157:- SN 1937A was discovered by Fritz Zwicky on 16 February 1937.
- SN 1955A was discovered by Fritz Zwicky on 14 April 1955.
- SN 2003J was discovered by R. Kushida, Tim Puckett, and Jack Newton on 11 January 2003.