1. The Evolving Planet – United States to experience first coast to coast total solar eclipse in 100 years! The solar eclipse will be most visible along a path that goes from Oregon to South Carolina on August 21.
Our galaxy could have 100 billion brown dwarfs or more, according to work by an international team of astronomers, led by Koraljka Muzic from the University of Lisbon and Aleks Scholz from the University of St Andrews. On Thursday 6 July Scholz will present their survey of dense star clusters, where brown dwarfs are abundant, at the National Astronomy Meeting at the University of Hull.
Brown dwarfs are objects intermediate in mass between stars and planets, with masses too low to sustain stable hydrogen fusion in their core, the hallmark of stars like the Sun. After the initial discovery of brown dwarfs in 1995, scientists quickly realised that they are a natural by-product of processes that primarily lead to the formation of stars and planets.
All of the thousands of brown dwarfs found so far are relatively close to the Sun, the overwhelming majority within 1500 light years, simply because these objects are faint and therefore difficult to observe. Most of those detected are located in nearby star forming regions, which are all fairly small and have a low density of stars.
In 2006 the team began a new search for brown dwarfs, observing five nearby star forming regions. The Substellar Objects in Nearby Young Clusters (SONYC) survey included the star cluster NGC 1333, 1000 light years away in the constellation of Perseus. That object had about half as many brown dwarfs as stars, a higher proportion than seen before.
The team calculated that the milky way could have a population of 25 to 100 billion brown dwarfs. Star formation rates in the Milky Way seem to have been higher in the past. If this is the case, the 100 billion number seems more likely. However, the calculations on the brown dwarf population were derived only for brown dwarfs more massive than 0.03 solar masses. Compare this to Jupiter’s mass, which is 0.00095 that of the Sun.
A US congressional committee is proposing that the US armed forces add a new military branch called the United States Space Corps. If this is passed it would be the first new branch of the armed forces since the Air Force was created in 1947.
The Space Corp would provide “combat-ready space forces” that enable the commanders of the combatant commands to fight and win wars. The Space Corps would fall under the Air Force in the same way the Marine Corps works with the Navy.