- Ville Puoskari
Hind's variable nebula
The dark nebulosity in the image is illuminated by a young star T Tauri, it was discovered in October 1852 by an English astronomer John Russell Hind. T Tauri stars are youngest stars that are visible in the optical wavelengths because stars any younger than this are still embedded in their shell of dust. T Tauri stars have acquired just enough mass in them to begin to create their own solar wind. This clears the dust surrounding them revealing the star inside it. Surrounding this star is Hind's variable nebula which is classified as a Herbig-Haro object. These objects are associated with newborn stars and they form when narrow jets of partially ionized gas shoot out of the stars accretion disk and collide with near by clouds of gas at a speed of several hundred kilometers per second. How this happens is not fully understood but it is believed that interaction between the accretion disk and the stellar magnetic field accelerates some of the accreting material from within a few astronomical units of the star away from the disk plane. I started this project in December, it turned out to be a difficult task because dark nebulas are.. Well, dark! Its the longest LRGB image I've ever taken with a total exposure time of ~24 hours. The Herbig-Haro object 255 can be seen in the center of the image around bright yellow star T Tauri.