Active Research

Virgo Overdensity

The Origin of the Virgo Overdensity

Dana Casetti, Terry Girard

The Virgo stellar structure - discovered as an overdensity of stars in photometric surveys - encompasses some 3000 square degrees and is located in the Milky Way halo. Using proper motions and radial velocities of members of this overdensity, we have determined that its orbit is on a very disruptive path through the Galaxy. N-body simulations suggest that the entire cloud-like Virgo structure is the tidal remnant from a disrupted massive (109 Msun) dwarf galaxy. The model also suggests that the progenitor of the Virgo overdensity is responsible for other stellar overdensities (i.e., the Pisces Overdensity, debris near NGC 2419 and near SEGUE 1) and NGC 2419 itself.

 

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Image Credits: (header) Image of prominence, SOHO (ESA & NASA)

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07.17.2014 Charting the heavens like never before, via Sloan Digital Sky Survey
Yale University scientists are involved all of the major aspects of the Sloan Digital Sky Survey, an initiative that spans four continents and includes 200 astronomers at more than 40 institutions. They will chart thousands of nearby galaxies, probe the composition of stars throughout the Milky Way with novel clarity, and measure the expansion of the universe during a particularly murky period.
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07.11.2014 Yale astronomers find seven galaxies using camera lenses
The astronomy project, using eight telephoto lenses lashed together, turned up seven new galaxies, but so far it’s unknown how far away they are. That’s why the scientists have rented time on the giant space-based Hubble telescope “to see if Hubble can find individual stars in the galaxies,” he said. That will tell them how far away the galaxies are. It’s a difficult task because the galaxies are all diffuse in nature.
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05.20.2014 Liang Yu, '14 B.S. has been awarded the Beckwith Prize from the Astronomy Department.
The prize is awarded to the undergraduate most proficient in some branch of astronomy or mathematics. In addition to the Beckwith Prize, Liang also was awarded Exceptional Distinction in the Major. Congratulations Liang!
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© 2014 Yale University. All Rights Reserved.