APOD: The Porpoise Galaxy from Hubble (2017 Feb 06)

[APOD Robot]

The Porpoise Galaxy from Hubble

Explanation: What's happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown, was likely a normal spiral galaxy -- spinning, creating stars -- and minding its own business. But then it got too close to the massive elliptical galaxy NGC 2937 below and took a dive. Dubbed the Porpoise Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction. A burst of young blue stars forms the nose of the porpoise toward the right of the upper galaxy, while the center of the spiral appears as an eye. Alternatively, the galaxy pair, together known as Arp 142, look to some like a penguin protecting an egg. Either way, intricate dark dust lanes and bright blue star streams trail the troubled galaxy to the lower right. The featured re-processed image showing Arp 142 in unprecedented detail was taken by the Hubble Space Telescope last year. Arp 142 lies about 300 million light years away toward the constellation, coincidently, of the Water Snake (Hydra). In a billion years or so the two galaxies will likely merge into one larger galaxy.

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[Ann]

This is a most striking picture of an extreme distortion of a spiral galaxy as a result of tidal forces arising from interaction with another galaxy. The picture is beautifully processed, too.

The spiral galaxy in question, NGC 2936, looks very blue, but it isn't dominated by star formation at all. We can clearly see star formation in the "beak" of the "penguin" (because it looks more like a penguin to me), and there is also star formation along the beautifully formed "neck". The latter feature is actually a part of the former ring around a likely galactic bar. There is also star formation along the "tail feathers".

(I love how a number of little galaxies - background galaxies, of course - seem to have been "caught" in the "tail feathers of the penguin", as if they were fish that had been caught in a net.)

And look at how that perfectly curved long dust lane stretches from beyond the edge of the "beak" all they way into the "tail feathers," where it breaks up.

The overall colors of NGC 2936 are unimpressive and not strikingly blue at all. The U-B of NGC 2936 is +0.02, which is moderately ultraviolet, whereas its B-V is 0,84, which is not blue at all. We can compare these colors with the colors of the obviously elliptical, non-starforming galaxy, NGC 2937. The U-B of NGC 2937 is +0.51, which is much redder than the U-B index of distorted spiral galaxy NGC 2936. But the B-V index of the elliptical galaxy is not much redder than the B-V index of the spiral galaxy, 0.94 versus 0.84.

NGC 2936 is a galaxy with a bright massive population of old red stars, plus localized clusters of bright new star formation. After NGC 2936 has merged with its elliptical neighbor, the galaxy merger product may experience one last bright burst of star formation, after it will likely settle into one large, red and dead, galaxy.

Ann

[ta152h0]

never know what is in that box of chocolates

[Curiouser]

While the upper 'spiral' galaxy is extremely distorted, the lower elliptic one appears to be unaffected. Is that consistent with the two interacting with each other?

[starsurfer]

Isn't this the Penguin Galaxy?

[neufer]

While the upper 'spiral' galaxy is extremely distorted, the lower elliptic one appears to be unaffected.
Is that consistent with the two interacting with each other?

One can only assume that the elliptical galaxy is more massive and much more compact.

I wonder why the image was mirror reflected

http://spacetelescope.org/videos/heic1311c/

[Ann]

Click to view full size image

Arp 142 and small blue edge-on galaxy.
NASA/ESA/Hubble Heritage Team

Can't resist showing you this alternative portrait of Arp 142, where the Penguin galaxy, sad to say, has fallen on its back.

But please note the small blue edge-on galaxy which is seemingly located right next to the interacting pair. My software refuses to tell me anything about this galaxy at all, not even its designation, so I know absolutely nothing about it and can't say if it is really located close to Arp 142, or if it is a background or, perhaps more likely, a foreground object.

But please note how blue this galaxy is, and how rich it is in star formation! Its yellow population, by contrast, is weak. If I am to guess, I would say that the B-V of this small galaxy can't possibly be redder than +0.5, and it may be lower too, perhaps +0.4. The Penguin galaxy, NGC 2936, with its B-V index of +0.84, is a yellow pumpkin in comparison with the little blue galaxy.

Ann

[canyonjeff]

Up in the sky, isnt it a hummingbird?

[De58te]

Click to view full size image

Arp 142 and small blue edge-on galaxy.
NASA/ESA/Hubble Heritage Team

Can't resist showing you this alternative portrait of Arp 142, where the Penguin galaxy, sad to say, has fallen on its back.

But please note the small blue edge-on galaxy which is seemingly located right next to the interacting pair. My software refuses to tell me anything about this galaxy at all, not even its designation, so I know absolutely nothing about it and can't say if it is really located close to Arp 142, or if it is a background or, perhaps more likely, a foreground object.

But please note how blue this galaxy is, and how rich it is in star formation! Its yellow population, by contrast, is weak. If I am to guess, I would say that the B-V of this small galaxy can't possibly be redder than +0.5, and it may be lower too, perhaps +0.4. The Penguin galaxy, NGC 2936, with its B-V index of +0.84, is a yellow pumpkin in comparison with the little blue galaxy.

Ann

From the Arp 142 link; an unrelated, lone, bluish galaxy, inconsistently cataloged as UGC 5130, appears to be an elongated irregular or an edge-on spiral. Located 230 million light-years away, this galaxy is much closer to us than the colliding pair, and therefore is not interacting with them.

[Visual_Astronomer]

Coincidently, I was looking at this very pair of galaxies last weekend - unfortunately one can not see this sort of detail, just two fuzzy blobs, still...

fyi - My software says that third galaxy is PGC 1237172.

[neufer]

Object of the Week Mar 18, 2012 - Arp 142 and his "Shred"
by Steve Gottlieb

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<<In his 1966 "Atlas of Peculiar Galaxies", Halton Arp classified this highly disrupted system as "Material Emanating From Elliptical Galaxies", while Madore, Nelson and Petrillo include it as a Ring system in their 2009 "Atlas and Catalog of Collisional Ring Galaxies".

NGC 2936 is a bright, disrupted galaxy with a highly irregular surface brightness and a curving shape with a faint tail.

NGC 2937 appeared bright, fairly small, oval, with a high surface brightness and a very small intense nucleus. The cores of 2936 and 2937 are separated by less than 1'.

Arp's "Shred" is PGC 1237172, a challenging galaxy attached to a 13th magnitude star just 1.3' NW of NGC 2936. Madore labels PGC 1237172 as a "collider" with NGC 2936, but in a 1967 paper titled "Peculiar Galaxies and Radio Sources" (ApJ...148..321), Arp argues that this faint streak is an ejected "shred" or "jet" of NGC 2936 as its major axis is aligned perfectly with NGC 2936.>>

[There was a drawing of a pacific cod here, but it triggered a content warning from the source domain, so it was removed.]scrod (n.) 1841, "young cod, split and fried or boiled,"

shred (n.) Old English screade "piece cut off, cutting, scrap," Old High German scrot, "scrap, shred, a cutting, piece cut off."

scrod (n.) 1841, "young cod, split and fried or boiled," possibly from Dutch schrood "piece cut off," from Middle Dutch scrode "shred". If this is the origin, the notion is probably of fish cut into pieces for drying or cooking.

• A Boston brahmin is on a business trip to Philadelphia. In search of dinner, and hungry for that Boston favorite, broiled scrod, he hops into a cab and asks the driver, "My good man, take me someplace where I can get scrod." The cabbie replies, "Pal, that's the first time I've ever been asked that in the passive pluperfect subjunctive.">>

[Ann]

Coincidently, I was looking at this very pair of galaxies last weekend - unfortunately one can not see this sort of detail, just two fuzzy blobs, still...

fyi - My software says that third galaxy is PGC 1237172.

Thanks! I told my software to take me to PGC 1237172, and it responded: Not a valid object. I also asked it to take me to UGC 5130, and it took me to a blank spot in the opposite direction of Arp 142 than the galaxy, which does show up in the grayscale of the objects.

Thanks for your help! And thanks to you too, Visual_Astronomer. So PGC 1237172 is indeed a foreground object. Thanks for telling me how far away it is!

Ann

[ta152h0]

hey look , you got an image of the Cod nebula, Cool, very sharp. They repaired the Hubble well . By the way, if they pointed the Hubble towards us, would it see beer cans on the side of the road ?

[Chris Peterson]

hey look , you got an image of the Cod nebula, Cool, very sharp. They repaired the Hubble well . By the way, if they pointed the Hubble towards us, would it see beer cans on the side of the road ?

A beer can on the side of the road would be about the size of a single pixel on the highest resolution camera. So it could theoretically detect the can, but don't expect to know the brand.

[neufer]

hey look , you got an image of the Cod nebula, Cool, very sharp.

• Fish & "Chip" Arp's "SCROD" nebula.

<<In 1966, Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) published the Atlas of Peculiar Galaxies, which contained photographs of 338 nearby galaxies that did not fall into any of the classic categories of galaxy shapes. One group of these, numbers 1 through 101, were otherwise conventional galaxies that appeared to have small companion objects of unknown origin. In 1967 Arp noted that several of these objects appeared on the list of quasars. In some photographs a quasar is in the foreground of known galaxies, and in others there appeared to be matter bridging the two objects, implying they are very close in space. If they are, and the redshifts were due to Hubble expansion, then both objects should have similar redshifts. The galaxies had much smaller redshifts than the quasars. Arp argued that the redshift was not due to Hubble expansion or physical movement of the objects, but must have a non-cosmological or "intrinsic" origin.

Arp also noted that quasars were not evenly spread over the sky, but tended to be more commonly found in positions of small angular separation from certain galaxies. This being the case, they might be in some way related to the galaxies. Arp's hypothesis is that quasars are local objects ejected from the core of active galactic nuclei (AGN). Nearby galaxies with both strong radio emission and peculiar morphologies, particularly M87 and Centaurus A, appeared to support Arp's hypothesis.

In his books, Arp has provided his reasons for believing that the Big Bang theory is wrong, citing his research into quasi-stellar objects (QSOs). Instead, Arp supported the redshift quantization theory as an explanation of the redshifts of galaxies. Arp did not waver from his stand against the Big Bang, and until shortly before his death continued to publish articles stating his contrary view in both popular and scientific literature, frequently collaborating with Geoffrey and Margaret Burbidge.>>

[DavidLeodis]

The explanation states the image was taken "last year" but the image does look very much like a reprocessing of the image used as the APOD of June 24 2013 https://apod.nasa.gov/apod/ap130624.html (the image seemed very familiar, so I searched the APOD archive). Links in the explanation also suggest that it is a reprocessing of an Hubble image that was taken in 2012.

[neufer]

hey look , you got an image of the Cod nebula, Cool, very sharp. They repaired the Hubble well . By the way, if they pointed the Hubble towards us, would it see beer cans on the side of the road ?

A beer can on the side of the road would be about the size of a single pixel on the highest resolution camera. So it could theoretically detect the can, but don't expect to know the brand.

[b][color=#0000FF]A farmer in Lavaca, Arkansas, painted his silo to look like a beer can.[/color][/b]

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<<Were the Hubble Space Telescope, with a 2.4 m telescope, designed for photographing Earth, it would be diffraction-limited to resolutions greater than 16 cm (6 inches) for green light at its orbital altitude of 590 km. This means that it would be impossible to take photographs showing objects smaller than 16 cm with such a telescope at such an altitude. Modern U.S. Imagery intelligence (IMINT) satellites are believed to have around 10 cm resolution; contrary to references in popular culture, this is sufficient to detect any type of vehicle, but not to read the headlines of a newspaper.>>