Locations of the 90 Cepheids used to measure the distance to NGC 6814 are marked with magenta circles. [Bentz et al. 2019]
This stunning composite Hubble photograph (credited to Judy Schmidt; click for the full 2.6’ x 2.6’ view) reveals a nearby Seyfert galaxy, NGC 6814. How do we determine the distances to galaxies like this one? One approach is to use variable stars known as Cepheids. Cepheids have a direct relationship between their luminosity and pulsation period, so if we observe a sample of Cepheids in a galaxy, we can use their pulsations to infer the distance to that galaxy. A team of scientists led by Misty Bentz (Georgia State University) recently used Hubble imaging to identify 90 excellent Cepheid candidates in NGC 6814, allowing them to estimate a precise distance to the galaxy. They find it to be just a brief hop away (relatively speaking): roughly 71 million light-years. To learn more about the authors’ study, check out the original article below.
Citation
“A Cepheid-based Distance to the Seyfert Galaxy NGC 6814,” Misty C. Bentz et al 2019 ApJ 885 161. doi:10.3847/1538-4357/ab48fb
