Wednesday, September 25, 2013

Hubble and Chandra Find Evidence for Densest Nearby Galaxy

M60-UCD1 galaxy, located near a massive elliptical galaxy NGC 4649, also called M60. Credit: X-ray: NASA/CXC/MSU/J.Strader et al, Optical: NASA/STScI

Astronomers using NASA's Hubble Space Telescope and Chandra X-ray Observatory and telescopes on the ground may have found the most crowded galaxy in our part of the universe. The ultra-compact dwarf galaxy, known as M60-UCD1, is packed with an extraordinary number of stars and may be the densest galaxy near Earth. It is providing astronomers with clues to its intriguing past and its role in the galactic evolutionary chain. M60-UCD1, estimated to be about 10 billion years old, is near the massive elliptical galaxy NGC 4649, also called M60, about 54 million light years from Earth. It is the most luminous known galaxy of its type and one of the most massive, weighing 200 million times more than our sun, based on observations with the W.M. Keck Observatory 10-meter telescope in Hawaii.

What makes M60-UCD1 so remarkable is that about half of this mass is found within a radius of only about 80 light years. The density of stars is about 15,000 times greater -- meaning the stars are about 25 times closer to each other -- than in Earth’s neighborhood in the Milky Way galaxy.

"Traveling from one star to another would be a lot easier in M60-UCD1 than it is in our galaxy, but it would still take hundreds of years using present technology," said Jay Strader of Michigan State University in Lansing. Strader is the lead author of a paper about the research, which was published Sept. 20 in The Astrophysical Journal Letters.

The 6.5-meter Multiple Mirror Telescope in Arizona was used to study the amount of elements heavier than hydrogen and helium in stars in M60-UCD1. The values were found to be similar to our sun.

"The abundance of heavy elements in this galaxy makes it a fertile environment for planets and, potentially, for life to form," said co-author Anil Seth of the University of Utah.

Another intriguing aspect of M60-UCD1 is the presence of a bright X-ray source in its center, revealed in Chandra data. One explanation for this source is a giant black hole weighing in at about 10 million times the mass of our sun.

Astronomers want to find out whether M60-UCD1 was born as a jam-packed star cluster or became more compact as stars were ripped away from it. Large black holes are not found in star clusters, so if the X-ray source is in fact due to a massive black hole, it was likely produced by collisions between M60-UCD1 and one or more nearby galaxies. M60-UCD1's great mass and the abundances of elements heavier than hydrogen and helium are also arguments for the theory it is the remnant of a much larger galaxy.

"We think nearly all of the stars have been pulled away from the exterior of what once was a much bigger galaxy," said co-author Duncan Forbes of Swinburne University in Australia. "This leaves behind just the very dense nucleus of the former galaxy, and an overly massive black hole."

If this stripping did occur, then the galaxy originally was 50 to 200 times more massive than it is now, and the mass of its black hole relative to the original mass of the galaxy would be more like that of the Milky Way and many other galaxies. The stripping could have taken place long ago and M60-UCD1 may have been stalled at its current size for several billion years.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra Program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Credit: NASA

1 comment:

  1. Both, Newton & Einstein had rejected aether before introducing their laws & theories. Whereas aether has been shown to be existing and containing the secrets of light & time. Once aether is accepted space is again finite & absolute and filled up with aether, the electric dipoles, and it is aether through which forces of nature are transmitted as against the irrational action at a distance through fields without knowing the physicality of the fields, time is emergent & relative depending upon motion of the observer, and as humans perceive it, time is emergent and matter is not absolute but emergent. (This alternative paradigm reveals that there is very powerful God who has power on matter & time and everything existing in the finite space and existence of God is the prerequisite for the creation & existence of universe ).
    In brief the scenario is as under
    Aristotle:- Space- absolute & finite; time- absolute, matter-absolute, light/radiation- not properly known

    Newton:- Space, time & matter same as Aristotle; light a wave-motion with corpuscular theory

    Einstein:- Space- interconnected with time & emergent, Time-emergen & interconnected with space & relative, matter & Energy (light/radiation) is absolute & transmutable and light/radiation as wave-motion with no clue as to what is light/radiation physically.

    Final state of existence:- Space-absolute & finite, time- emergent & relative depending on the motion of the observer/body with respect to aether at rest frame of reference, matter-emergent & finite, light/radiation- a electromagnetic disturbance of electric dipoles of aether creating a wave motion and all forces of nature being
    electromagnetic forces which is being transmitted through aether, the electric dipoles.

    Following is the list of my published scientific articles in peer-reviewed journals & sites where these articles are available
    1. Experimental & Theoretical Evidences of Fallacy of Space-time Concept and Actual State of Existence of the Physical Universe
    2. Foundation of Theory of Everything: Non-living Things & Living Things (Revised version on World Science Database, General Science Journal, Vixra and in my profile)
    3.Michelson-Morley Experiment: A Misconceived & Misinterpreted Experiment
    4. Energy Theory of Matter & Cosmology (Revised version on World Science Database, General Science Journal, Vixra and in
    my profile)
    5. 'On the Electrodynamics of Moving Bodies' by Albert Einstein is Based on Trickeries ( Feb.2012)
    6.Ultimate Proof of Energy Theory of Matter & Cosmology
    7. Theory of Origin & Phenomenon of Life
    These publications are available at the journal site of Indian Journal
    of Science & Technology (a peer-reviewed journal)
    (March 2012,oct 2010, oct 2011,Aug 2010) and also on,, viXra, Intellectual Archives,
    ResearchGate & in my profile.
    On the basis of above-mentioned articles an open challenge has been put forward to the adopted paradigm of physics. The standing (till date) open challenge could seen at