Due to the plasma wind coming from the Sun, the shape of a comet’s tail changes in a short time. This time Ishigakijima Astronomical Observatory’s MURIKABUSHI telescope was able to capture this situation. Comet Lovejoy (C/2014 Q2) grew bright enough to be observed with the naked eye in January of 2015. A plasma wind blows out of the Sun and causes the tails stretching out from the comet to converge as if they were being bundled together; here they are pictured streaming away. The change in the comet’s tail extending out to several hundreds of thousands of kilometers in length occurred in less than 20 minutes. You can appreciate that this is a dynamic aspect of the Solar System.

Dynamically Bundled Comet Tails

Comet Lovejoy was discovered by the Australian amateur astronomer Terry Lovejoy in August of 2014. The coma, glowing blue-green through the emission lines of neutral molecules like C₂ (diatomic carbon), and the ion tail (plasma tail), glowing through the molecular emission lines of CO⁺ (ionized carbon monoxide) and H₂O⁺ (ionized water), are characteristic of comets. Ionized molecules in the coma stripped away by the flow of plasma (ionized gas) known as the solar wind form the ion tail. This video captures the situation as the ion tails rapidly fold together and stream away due to the effects of the solar wind. This video was made from 138 frames, each shot with a 30 second exposure time. To make the movement of the tails easy to see, in each frame the coma and tail components (the static parts) have been subtracted from the original image. This kind of observation of dynamic changes makes the most of the quality of Ishigakijima’s starry sky and the light gathering power of the 105 cm diameter MURIKABUSHI Telescope.

Text by: Hidekazu Hanayama (Ishigakijima Astronomical Observatory)
Translation by: Ramsey Lundock (NAOJ)