A new study published by a team of astronomers (Gillessen, et al.) estimates that the G2 cloud will come about 144 astronomical units (AU) from the Galactic core at its time of closest approach, which is about 14 AU further away than was determined in an earlier study reported by Phifer et al. which was discussed in our previous posting. Also whereas Phifer et al. estimated the date of closest approach to be in 2014 around February 15th (± 2 months), the new report estimates that the date of closest approach will come about a month and a half later around April 2nd (± 3 weeks). Based on their simulation of the trajectory of the cloud, the Gillessen group concludes that the cloud may not contain an embedded star or planet, although they find it difficult to explain how the cloud could have maintained its compactness over such a long period in its orbital passage. If indeed there is no embedded planet or star, then the chances of a superwave being generated are significantly reduced. This group reports that a significant fraction of the cloud's gas has already orbited past the pericenter position and is seen to be coming towards us in its orbit, rather than away from us. Most of the cloud is seen receding from us as it approaches the GC.
August 15, 2013