Galaxy Duo Makes For Strange Pair
Two very different galaxies feature in this family portrait taken by the NASA/ESA Hubble Space Telescope, together forming a peculiar galaxy pair called Arp 116. The image shows the dramatic differences in size, structure and colour between spiral and elliptical galaxies. Credit: ESA/HST
Way out in space some 54 million light-years away from Earth is a giant galaxy cataloged as Messier 60 – the third brightest galaxy in the Virgo cluster. Nearby at 63 million light-years away is a companion galaxy known as NGC 4647. Together this “odd couple” is known as Arp 116. However, are they really a connect pair or does it just look that way? The dynamic image above is a combination of visible and infrared exposures from Hubble’s Advanced Camera for Surveys and Wide Field and Planetary Camera 2 It shows two very different galaxy types – M60, a huge elliptical – and NGC 4647, spiral galaxy that’s roughly the size of the Milky Way.
Out of the 1,300 galaxies that constitutes the Virgo Cluster, Messier 60 ranks third with its diameter of approximately 120,000 light-years and mass about a trillion times that of the Sun. At its heart beats a huge black hole about 4.5 billion solar masses in size and one of the most massive black hole ever found. By comparison, NGC 4647 is tiny, only about a third of M60′s size and significantly lower in mass.
Over the years, astronomers have tried to solve the puzzle as to whether or not these two galaxies are interacting – or just connected by line of sight. From our point of view, they overlap, seeming to be connected. However, there just isn’t any evidence of new star formation – a sure sign the pair is combining. So what is the answer to the riddle? Thanks to recent studies utilizing detailed Hubble images, it appears the two may just be beginning a cosmic dance. It would appear there is some tidal interaction going on between the two!
“In interacting pairs of galaxies, the mutual gravitational pull that the galaxies exert on each other typically disrupts gas clouds, much like tides on Earth are caused by the Moon’s gravity.” says the Hubble team. “This disruption can cause gas clouds to collapse, forming a sudden burst of new stars.”
Even if there isn’t any starburst activity, that doesn’t mean we haven’t caught two galaxies at the very beginning of interaction. If nothing else, they are very close to one another and gravity will certainly combine the two in the future.
Let’s dance…
Original Story Source: Hubble Space Telescope News Release.
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