Free Astronomy Magazine November-December 2015

ASTROBIOLOGY rotation; since KIC 8462852 rotates in just 21.1 hours, it would be very easy to check the presence of a huge “sunspot”. 3) Around the star could orbit a giant dark and com- pact body, but there is nothing known that at that kind of size could not be directly seen; moreover, no appreciable changes in the radial velocity of the star were re- corded, which means that in orbit there are no relevant masses. 4) KIC 8462852 could be surrounded by a disk of dust and debris with local accumulations generated by recent collisional events of asteroids or planets, but in that case there would be an excess of infrared radiation, which instead is com- pletely absent. 5) Is there perhaps an error in the recording of photometric data by Kepler? No errors detected! At this point the researchers assessed the possibility that a star very close to KIC 8462852, such as to merge the two light emissions, was the real responsible for the abnormal drops in light. Indeed, at just 1,000 astronomical units (almost 6 light- days) from KIC 8462852 there is a red dwarf, perhaps gravitationally bound to the first, perhaps only transiting. This star is however too small to somehow influence the light curve of KIC 8462852, but it could have disrupted a possible cometary cloud of the latter (something similar to our Oort Cloud), diverting a large number of nucleus towards the star, where they would tempo- rarily concentrate obscuring the disk. This is the preferred solution by Boyajian and colleagues but, frankly, the transitori- ness and spatial narrowness of the concen- tration of cometary nucleus in the vicinity of the star would require dynamic coinci- dences, such as to make this scenario rather n T he star field containing KIC 8462852 (shown by dashes), photo- graphed by Gian- luca Masi on 15 October 2015, as part of The Vir- tual Telescope Project. far-fetched to say the least. The only ad- vantage of the “cometary solution” is that it does not generate a significant surplus of infrared radiation. If none of the above causes were valid, there are only two other possibilities: ei- ther an unknown – or at least underesti- mated − phenomenon, or the presence around the star of an artificial megastruc- ture. The same researchers consider the lat- ter a last resort and the best that can be said at the moment is that the issue re- mains unresolved, because neither the ar- chival research of images and photometric data (about 700 measurements from the years 1900 to 2000) and nor the new obser- vations of the star have provided further information. Now it is being thought to point the 100- meters radiotelescope of Green Bank to- wards KIC 8462852, hoping to pick up alien signals, which, given the distance of the star, would have however been emitted 1,480 years ago. Considering the myste- rious phenomenon that has characterized KIC 8462852 and its relatively high bright- ness, this star should be a priority target for many amateur astronomers.