A family portrait of galaxies

Sep 06, 2012
Two very different galaxies feature in this image taken by the NASA/ESA Hubble Space Telescope, forming a peculiar galaxy pair called Arp 116. Arp 116 is composed of a giant elliptical galaxy known as Messier 60, and a much smaller spiral galaxy, NGC 4647. Astronomers have long tried to determine whether these two galaxies are actually interacting. Although they overlap as seen from Earth, there is no evidence of new star formation, which would be one of the clearest signs that the two galaxies are indeed interacting. However, recent studies of very detailed Hubble images suggest the onset of some tidal interaction between the two. Credit: NASA, ESA

(Phys.org)—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.

Arp 116 is composed of a known as Messier 60, and a much smaller spiral galaxy, NGC 4647.

Being a typical elliptical galaxy, Messier 60 on its own may not be very exciting to look at, but together with its adjacent spiral friend, the pair becomes a rather interesting feature in the .

Messier 60 is very bright—the third brightest in the Virgo , a collection of more than 1300 galaxies. It is noticeably larger than its neighbour, and has a far higher mass of stars. M 60, like other elliptical galaxies, has a golden colour because of the many old, cool and red stars in it. NGC 4647, on the other had, has many young and hot stars that glow blue, giving the galaxy a noticeably different hue.

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This video shows Hubble observations of Arp 116, a pair of galaxies in the constellation of Virgo. It is made up of M60, a large elliptical galaxy, and a smaller, bluer spiral galaxy, NGC 4647. It has long been unclear whether the two galaxies are actually interacting, or whether they simply appear close together from our distant vantage point. However, detailed studies of Hubble pictures suggest that the pair are beginning to experience tidal forces. Credit: NASA, ESA. Music: R. Vreeland

Astronomers have long tried to determine whether these two galaxies are actually interacting. Although they overlap as seen from Earth, there is no clear evidence of vigorous new star formation. 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. This disruption can cause to collapse, forming a sudden burst of new stars.

Although this does not appear to have happened in Arp 116, studies of very detailed suggest the onset of some tidal interaction between the two.

Regardless of whether they are actually close enough to be interacting, however, the two galaxies are certainly near neighbours. This means we see the two galaxies at the same scale, making Hubble's family portrait a textbook example of how giant elliptical galaxies differ in size, structure and colour from their smaller spiral brethren.

Surprisingly Messier 60 was discovered independently by three different astronomers in 1779. Johann Gottfried Koehler of Dresden first spotted it on 11 April that year while observing a comet, the Italian Barnabus Oriani noticed it a day later, and the French Charles Messier saw it on 15 April. Charles Messier then listed the galaxy in the Messier Catalogue.

Having photographed the with the 5-metre Hale telescope, US astronomer Halton Arp included it in his Atlas of Peculiar Galaxies, published in 1966. The catalogue contains images of 338 "peculiar galaxies"—merging, overlapping and interacting galaxies.

This large image is a mosaic of images in visible and infrared light taken by Hubble's Advanced Camera for Surveys and Wide Field and Planetary Camera 2.

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cantdrive85
1.4 / 5 (12) Sep 06, 2012
Funny, the reason these two are considered "peculiar" by Mr. Arp is their close proximity and their high red-shift differentiation. One of the 338 examples where the use of red-shift has been shown to be a highly inaccurate method of determining distance on a cosmic scale. No mention of this in the article though, another example of how purveyors of the standard theory "conveniently" omit uncomfortable facts that don't support their theories.
loneislander
1 / 5 (4) Sep 06, 2012
...the use of red-shift has been shown to be a highly inaccurate method of determining distance on a cosmic scale. No mention of this in the article though,... [...] ..."conveniently" omit uncomfortable facts that don't support their theories.


As I look in that wonderful resource Wikipedia (particularly wonderful in this case because anyone can edit any article) this problem with red-shift is also "conveniently" omitted. Hard to imagine that it's "highly" inaccurate... must be just ordinary inaccurate huh? :)
hemitite
not rated yet Sep 06, 2012
Imagine being on a planet on the fringe of one of these elliptical giants - part of the year the night sky could look like a great white sheet with a bright center. There would be little dust and gas to block that view.
julianpenrod
1 / 5 (2) Sep 06, 2012
A number of peculiar points.
Among other things, Messier 60 is just the hude elliptical galaxy. The spiral next to it is NGC 4647. Even in a moderate telescope, the two would be apparent and distinct. Why didn't Messier record them as two different objects? For that matter, why did Messier only record the elliptical and not the spiral?
The question of tidal interaction between the two galaxies raises a question, too. If there truly is "Dark matter", wouldn't that cause apparent "tidal interactions" in galaxies, especially galaxies not near any other galaxies? Wouldn't that be a sign of "dark matter"? Does "dark matter" clump up to particularly influence galaxies at certain spots, or does it distribute itself absolutely uniformly, no matter what, everywhere?
vidyunmaya
1 / 5 (3) Sep 07, 2012
Sub: UPE Model Index
An elliptical Galaxy -is an index to cosmic Pot Energy. Asherical Galaxy and a spiral follow down in sequential flow dynamic analysis. Unversal plasma Energy model-IEEE- iCOPS-1991-my paper
starts the dialogue to inroduce the subject to space Plasma groups-Alfven groups. Further outlines were given in my reports-made available as books. the cover pages reveal the onset to discussion-dimensional knowledge frames to interlinks heart and center of Universe- idntified around 1065 Light years that provide Cosmological index to Universe.
I note with interest Messier 60 and nGC 4647 around 120,000 LY.
Confirmatory data helps in advancement of Knowledge Base.
http://hubblesite.../2012/38
vidyardhicosmology [dot]blogspot [dot]in/2011/10/light-flow-interaction-plasma-vision [dot]html
vidyunmaya
1 / 5 (3) Sep 07, 2012
Sub: ARP116-NGC4647 -Combination-around 60 MLY
Please note correction as per Hubble.M60 lies roughly 54 million light-years away from Earth; NGC 4647 is about 63 million light-years away. This image combines exposures from Hubble's Advanced Camera for Surveys and Wide Field and Planetary Camera 2.
MY NOTES: The combination touches the peak -see DMVT Structure as part in heart of Universe.-Cosmology vedas Interlinks Confirmatory Index-to cosmologial Index.vidyardhi nanduri
Q-Star
2 / 5 (4) Sep 07, 2012
cosmic Pot Energy


It's all becoming clear to me now. Cheech & Chong, right?
Fleetfoot
5 / 5 (3) Sep 08, 2012
Funny, the reason these two are considered "peculiar" by Mr. Arp is their close proximity and their high red-shift differentiation. One of the 338 examples where the use of red-shift has been shown to be a highly inaccurate method of determining distance on a cosmic scale. No mention of this in the article though, another example of how purveyors of the standard theory "conveniently" omit uncomfortable facts that don't support their theories.


Redshifts from the SIMBAD database:

M60: 0.00369
NGC4647: 0.00472

In other words, redshift says they are both very close to us and at similar distances. In fact neither galaxy is at "high redshift", these values are so low that their proper motions will dominate over the Hubble flow component.

Another example of how crank posters on this site "conveniently" omit uncomfortable facts that don't support their theories.

It is also an example of some of the good astronomy Arp originally did.
ValeriaT
1 / 5 (1) Sep 08, 2012
This is indeed a valid point - but many quasars don't fit the Hubble expansion model anyway. But with compare to M60/NGC4647 galaxies the quasars tend to be pretty distant in general. It may serve as another example of how proponents of mainstream physics on this site "conveniently" omit uncomfortable facts that don't support their theories, etc...
Fleetfoot
5 / 5 (2) Sep 08, 2012
This is indeed a valid point - but many quasars http://phys.org/n...752.html the Hubble expansion model anyway. ... It may serve as another example of how proponents of mainstream physics on this site "conveniently" omit uncomfortable facts that don't support their theories, etc...


The article you quote is 6 years old and out of date. Not only do quasars show time dilation as expected, they are sufficiently consistent that they may in future be used as another "standard candle":

http://physicswor...istances

The science:

http://arxiv.org/abs/1204.5191

This may serve as another example of how cranks on this site "conveniently" omit uncomfortable facts that don't support their theories.