A strange triangle-shaped galaxy observed by Hubble

Halton Arp was a brilliant American astronomer who believed that his observations of exotic galaxies challenged the Big Bang theory. He thus compiled an atlas of hundreds of these objects, on which the Hubble telescope made several interesting zooms. NASA and ESA regularly publish space telescope images of these galaxies, the most recent of which relate to Arp 143 and Arp 282.

That NasaNasa andESAESA have recently uploaded some amazing photos taken of telescopetelescope Hubble shows some examples of galaxiesgalaxies collides which is part of TheAtlas of Peculiar Galaxies, also commonly called atlas Arp. It is an astronomical catalog that shows certain galaxies that we initially owe to the deceased astronomerastronomer The American Halton Arp (1927-2013). He first published it in 1966, and when he died he listed 338 galaxies.

Halton Arp, like Fred Hoyle, Margaret and Geoffrey Burbidge, will continue to be opposed to the theory of big bangbig bang in the late 1960s (despite the discovery of cosmic radiationcosmic radiation) until his death. He, like Hoyle, questioned the interpretation of the spectral shift according to the Hubble–Lemaître law in terms of the expansion of space. This shift had to have another interpretation, for example within the framework of a theory of tired light that involved a continuous loss ofenergyenergy photons emitted by starsstars with the distance they travel without this loss corresponding to a shift towards long wavelengths, therefore from blue to red, due to expansionexpansion continuous and accumulated wavelengths of photons due to the expansion of space during their journey.


The pair of interacting galaxies collectively known as Arp 143. The pair contains the distorted star-forming spiral galaxy NGC 2445, right, and its minus companion, NGC 2444, left. © NASA, ESA, STScI and J. Dalcanton (Center for Computational Astrophysics/Flatiron Inst., UWashington)

Galaxies that do not invalidate the Big Bang theory

However, the theory of tired light was untenable, as the great Russian cosmologist Yakov Zeldovich quickly showed for the first time. According to the known laws of physicalphysicalany loss of energy would, according to the theory of tired light, involve a random loss of the amount of movementthe amount of movement for photons by interaction with their surroundings, for example intergalactic dust, so that the images of starsstars and galaxies would become more and more degraded with distance, which is absolutely not observed.

Furthermore, as cosmologist Ned Wright explains, the relativistic expansion of space implies that the light curve evolution time of the explosions of supernovaesupernovae must appear dilated according to a very precise law, an expansion which no theory of tired light can predict. But not only has the phenomenon and the predicted law been observed, but the disagreement between the theory of tired light and the observations is 11 sigma, as the scientists say in their jargon. It is a colossal disagreement.

Arp was concerned by the fact that some of the objects in his catalog showed interacting galaxies or at least appeared so likely because of their proximity in the firmament. However, these galaxies had different spectral shifts, contradicting their apparently close associations involving distances similar to The Milky WayThe Milky Way. Logically, Harp deduced that this disproved the standard theory of spectral shift. A well-known example is The Stephan QuintetThe Stephan Quinteta visual grouping of 5 galaxies located in the constellation pegasusthe constellation pegasus and observed for the first time by the French astronomer Édouard Stephan in 1878. In fact, only 4 galaxies are truly interacting and, as in all the other cases that concerned Harp, it was possible to show that the differences in displacement actually was due to different spatial distances and the associations on the firmament were simple asterismsasterisms like the constellations.


Comments for Arp 143. For a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Select “French”. © NASA’s Goddard Space Flight Center, Main producer : Paul Morris

Hubble and Arp’s catalog

It shows the latest image uploaded by NASA and ESA NGCNGC 2444, a lenticular ring galaxy located in the constellation Lynx at about 180-200 million.light yearslight years of the Milky Way discovered by the French astronomer Édouard Stephan in 1877, as well as NGC 2445, also a ring galaxy, but irregular, and undoubtedly interacting with NGC 2444.

NGC 2445 was also discovered in 1877 by Édouard Stephan and the two galaxies are today together called Arp 143. and relatively young, which are extremely bright. That astrophysicistsastrophysicists believe that ring galaxies form when a galaxy passes through the center of a larger galaxy. that gasgas self-gravitating stars in galaxies can be considered essentially collisionless, but gravitational perturbations caused by such an event can cause shock waves in the interstellar medium containing cloudsclouds molecules that cause their collapsecollapse gravity and thus a widespread wave of star formation.

This is thought to have happened to Arp 143 between 50 and 100 million years ago, hence the burst of new star formation visible in NGC 2445. The triangular shape of this galaxy is thought to be due to gravitational forcesgravitational forces distortion of its ring structure. NGC 2444 contains old stars and no new star births because it lost its gas long ago, long before this galactic encounter.

A little more than a week before Arp 143, NASA had posted another image obtained with HubbleHubble shows Arp 282, an interacting galaxy pair consisting of the Seyfert galaxy NGC 169 (bottom) and the galaxy IC 1559 (top). NGC 169 is a spiral galaxy located in andromeda constellationandromeda constellation about 205 million light years from the Milky Way. It was discovered by Irish astronomer RJ Mitchell in 1857.

These two galaxies are interacting via of tidal forcestidal forces which distorts them and ejects gas and stars. They house both active galactic nucleiactive galactic nuclei from which it seems well established for some time that they derive their energygrowthgrowth of fabricfabric at central supermassive black holes.


Several items from the Halton Arp catalog are featured in this video. © Nas, Esa, go to astronomy

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