Electra, designated 17 Tauri, is the third-brightest star in the Pleiades open star cluster (M45), visible to the naked eye with an apparent magnitude of 3.7. It belongs to the spectral class B6 IIIe and is a fast rotator with a projected rotational velocity of 181 km/s. Electra is classified as a Be star, which means it has prominent emission lines of hydrogen in its spectrum. The star is surrounded by a gaseous disk created by radiation-driven mass loss and rapid rotation, which contributes to the reflection nebula vdB 20.
Names and Catalog numbers
- Electra
- 17 Tauri
- vdB 20
Position and the cosmic neighborhood
Electra and its associated reflection nebula vdB 20 are part of the famous Pleiades open star cluster, also known as the Seven Sisters. The Pleiades cluster is one of the brightest and largest open clusters in the sky, easily visible to the naked eye. It is located in the constellation Taurus, about 14 degrees northwest of the bright star Aldebaran. The cluster, including Electra and vdB 20, can be seen rising prominently in the sky from October to April, making it an excellent target for astrophotographers during these months.
Nice to Know
- The reflection nebula vdB 20 is created by the light from Electra illuminating surrounding dust particles.
- Electra’s rapid rotation causes its equatorial radius to be greater than its polar radius, resulting in gravity darkening, which can be an interesting challenge for astrophotographers to capture.
- The star shows low amplitude variability in its brightness, detected by Kepler/K2, with several periods of oscillation, potentially offering opportunities for time-lapse astrophotography.
- Infrared observations of Electra have shown an excess level of radiation, likely due to a gaseous disk created by periodic ejections of material, which contributes to the nebulosity visible in astrophotographs.
Brightness, distance and size
Electra, the star associated with vdB 20, has an apparent magnitude of 3.70, making it the third brightest star in the Pleiades cluster. It is located approximately 400 light-years away from Earth. While the exact size of the reflection nebula vdB 20 is not provided in the search results, it is part of the larger Pleiades cluster, which appears to be about 110 arcminutes across in the night sky. The nebula itself is likely much smaller, possibly a few arcminutes in size, but its exact dimensions would depend on the exposure and sensitivity of the astrophotography equipment used to capture it.
