APOD 4.1

Pictured above is something that is certainly never seen often: a black hole. The gas surrounding GRO J1655-40 has been flickering an unusual 450 times per second, an attribute that may indicate that a black hole is present. It's central object has a projected mass to be about 7 times that of our sun, and the flickering explains an object that is spinning very rapidly. 

APOD 3.8

In Corvus, two galaxies are colliding, ripping apart each other's gravitational powers. The dust and gas will continue to collide, but the stars will not due to huge amounts of space between them. These two galaxies have been colliding for over a hundred million years. Throughout their collision, dust pillars and molecular clouds are being compressed, causing the birth of millions of stars, many of which will be contained in clusters. 

APOD 3.7

Pictured above is the Running Chicken Nebula, spanning 70 light-years at a 6,000 light year distance, and is of particular importance due to the "eggs" forming into stars. The dark globules in the center of the picture are known as Thackeray's Globules, the sites for gravitational star formation and are quickly being eroded away from the radiation of the young stars. The stars here form the open cluster Collinder 249. 

Quarter 3 Biography: Alvan G. Clark

     Alvan Graham Clark, born on July 10, 1832 in Fall River Massachusetts, was an American astronomer and telescope-maker. His father, Alvan Clark Sr., was the founder of an optical firm called Alvan Clark and Sons. He created a 40-inch lens (the largest in today's world), which is currently housed at Yerkes Observatory. Alvan G. was the first to make an observation of Sirius B in Massachusetts, the magnitude 8 companion of Sirius and the first known white dwarf. 
     Alvan, when compared to his brother, George, was described as unusually attractive and intelligent. He had an incredible love of literature and a very retentive memory. His wife was Mary Mitchell Willard, who was a member of a Cambridge-Harvard family, which surely only enhanced his sociability. At age 16, he enterd a machine shop, learning the trade before joining the family firm. 
     Alvan G. had the opportunity to follow in his father's footsteps and learn the trade of lens making, which allowed him to create high-quality telescopes for his own scoping of the sky. In his early life, he worked on a contract with the University of South Carolina to create two glass disks in 42-inch diameters. Clark was soon discovered by a man named George Ellery Hale, who was interested in purchasing lenses for the Yerkes Observatory. 
     Alvan G. first noticed Sirius B while testing a new 18.5 inch refractor telescope on January 31, 1862. With Sirius being such a bright star (the brightest star in the night sky, and located in Canis Major) and Sirius B much less in comparison, the naked eye only perceives Sirius as a single star, when it is in fact a binary. This binary system consists of a spectral type A1V, Sirius A, and spectral type DA2, Sirius B. His accidental observation allowed astronomers to make more sense of their universe with a new type of star to study. The telescope he used to make this observation is now at the Dearborn Observatory of the Northwestern University in Evanston, Illinois. 
    Clark was awarded the Lalande Prize of the Paris Academie des Sciences for his discovery, an award given to someone demonstrating great feats in astronomical performance each year. He later joined the American Association fo rthe Advancement of Science in 1879 and was elected to fellowship. He became a resident fellow of the American Academy of Arts and Sciences in 1894 and was elected a member of the Societe Astronomique Dde France. 
     He died on June 9, 1897 at 64 years of age.