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.



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


08.27.2014 Yale scientists see the birth of a massive galaxy, hidden by dust
Graduate student Erica Nelson and her collaborators have discovered a window into the early, violent formation of the cores of the universe’s monster galaxies, obscured behind walls of dust, using the NASA/ESA Hubble Space Telescope and a telescope from the W.M. Keck Observatory in Hawaii. The discovery offers important clues about an early phase of galaxy development, from a time just 3 billion years after the Big Bang. The research appears in the journal Nature.
08.07.2014 How do you feed a hungry quasar? With a ‘super boost,’ scientists say
“The first black holes are believed to be remnants left behind after the first stars burned out completely,” said Priyamvada Natarajan, a Yale University professor of astronomy and physics. “The puzzle has been how these ‘seed’ black holes grew into the monsters that we now see within the time available, a few billion years at best.”
Priya Natarajan
07.31.2014 Yale Researcher Helps Find Most-distant ‘Spyglass In Space’
Yale postdoctoral researcher Ivelina Momcheva says she can see clusters of young stars being formed in distant galaxies.

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University of Virginia
The Role of Dwarf-Dwarf Interactions in the Hierarchical Assembly

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© 2014 Yale University. All Rights Reserved.