Astronomy Briefly

brought to you by Duane Dunkerson


Article Archives

Contact Me



The Arp Atlas of Peculiar Galaxies, A Chronicle and Observer's Guide by Jeff Kanipe and Dennis Webb, Willman-Bell, Inc., 2006.

by Duane Dunkerson

Nowadays they rarely put so much effort into providing the material, text, and photographs for a book. The publisher is to be commended for bringing the contributions of Mr. Kanipe and Mr. Webb to completion. The book is of textbook size and weight. The pages are large, with a white gloss. Only the covers are in color. The book was produced to commemorate the 40th anniversary of the Atlas of Arp and its publication.

Arp, in any case, took photographs, and did not do CCD imaging. He used negative plates so as to best show the details of the peculiarities among the galaxies that he had selected. The photos were to be factual and not necessarily pretty. The selection process by Arp, the authors frankly state, had a psychological element involving what he thought was "peculiar".

The selection, reproduced in this book in full with Arp's original comments, was the result of the aforementioned selection process and what he could find in the far reaches of space. From those places, he began in 1962 to gather the photos taken with the 200 inch Palomar telescope in California. His atlas was published in 1966. He was aided by having his attention directed to interesting objects as had been found by others such as Vorontsov-Velyaminov, Zwicky, Herzog, Wild, Morgan and Mayall.

The number of objects recorded totaled 338. These objects were not all entirely unknown to other astronomers. These usual objects were felt to be so far into outlier land in regard to shapes of galaxies, in general, that they were ignored. Arp thought the peculiarities, though peculiar, were not necessarily fully unique. He felt the peculiar could be put into categories according to shape or lack of shape. The Atlas showed what he found.

Amateur astronomers have since observed them visually and obtained CCD images. Amateur telescopes these days can be huge compared to what amateurs routinely had in their possession in Arp's day. Arp's objects are mostly faint or very faint. The amateurs mentioned in this book conducted their activities with apertures in inches of : 32,25,24,20,18,17.5,16,,12.5,10, and 8. The lesser apertures are generally used for imaging. The greater apertures can be for imaging or also for visual observations. The results of the amateurs are at the back of the book with many pages of their visual and CCD imagery. There are maps and charts, observing highlights, notes and visual impressions. The amateurs who completed the work are profiled.

If a pleasant diverging collection of objects was all there was to it, then that would be the end of the story. But something else, recounted in the authors' Chronicle, The Peculiar Universe of Halton Arp, relates some diverging but not necessarily pleasant facts about what was thought of Arp's Atlas beyond a cursory page-flipping appreciation of these strange objects.

It all began in the library of the Palomar Observatory in 1966. Arp had received a letter from Sérsic about three compact radio sources close to NGC 6438, a bright and disturbed galaxy. The letter prompted Arp to check further into locations of other radio sources. After a few weeks, Arp had found 75 such sources associated with over 30 different galaxies. Usually the associated galaxies were elliptical in shape and not your run-of-the- mill spiral galaxies. Also, some of the radio sources had much higher redshifts than the associated galaxy. Therefore, Arp would reason that the radio sources, some known as quasars, had intrinsic redshifts not dependent on their distance from us.

All galaxies have redshifts of the spectral lines derived from the atoms making up a galaxy. Edwin Hubble, in the 1920s, had shown our Universe was not as local as we thought. The distance involved to the far corners of the Universe was indeed "astronomical". In addition, Hubble found that the further away from us was a galaxy, the greater was its redshift. So how could the radio sources that Arp was bringing to the attention of other astronomers be a worry to the other astronomers?

The worry came because Arp also found a physical tie-in of filaments or bridges of substances connecting a "near" galaxy and some of the radio sources that had redshifts indicating that they must be far away. Arp asserted in a 1966 Caltech colloquium that quasars (the radio sources) were not remote. No, no said most astronomers, those are chance alignments in the sky. The proximity is only apparent. A distant quasar is placed in the sky so as to be seen as near a nearby object.

Some astronomers wanted a debate about this matter. So in 1972, John Bahcall and Arp debated. Most thought, or wanted to think, Bahcall "won". Of Bahcall, Arp said - "…John Bahcall, at that time a very ambitious kind of a guy, said he'd do it. And it wasn't even his field then, but he was just ripe for any opportunity."
Others, not many, lined up behind Arp. Such notables as Fred Hoyle and the Burbidges always supported him. They thought Arp deserved to further explore the connections and contentions he had brought up. Instead, Arp was denied use of any telescopes at Mt. Wilson and on Palomar. He had been a staff astronomer at both places and had been initially appointed to what was assumed to be a permanent placement with these prestigious institutions then having the only large enough telescopes to which he had had routine access.

Adding to the mix was the background concern that if the redshifts of the quasars were not indicative of distant objects, then other redshifts of other objects would be called into question and astronomers had already decided for decades that the "cosmological" redshifts showed that the Universe was derivative of a Big Bang. This Big Bang had produced an expanding Universe as shown by recessional redshifts for galaxies that supported the idea of an expanding Universe.

No, no said the overwhelming majority of astronomers, we want to keep our Big Bang and the astrophysics that goes with it. Besides, there are not that many oddball galaxies. Quasars have nothing to do with them. Quasars near peculiar galaxies are statistically juxtaposed. Leave the Hubble (and others) orderly classification of galaxies alone. By 1981, representatives of this majority wanted Arp to lie about what he was doing or get off his topics altogether. He would have to "fundamentally redirect his efforts".

Arp noted galaxies are not just optical entities. There are also x-rays, radio, gas, dust, and infrared components. Gravity was not the only force shaping galaxies as magnetism could play a big role. In 1987, Arp and Madore released A Catalogue of Southern Peculiar Galaxies and Associations. There were 77,383 galaxies that they had examined and 8% were peculiar in the usual personal and psychological way. Also in 1987, Arp and Sulentic reported an appendage that appeared to link NGC 4319, a Seyfert galaxy, and Markarian 205, a quasar. No, no said the other astronomers, it is overlapping light contours or an artifact. In 1983, Sulentic did more refined image processing of Markarian 205. The result confirmed the earlier assertions by himself and Arp. Arp in 1994, using ROSAT observations, found three quasars of differing redshifts associated with Markarian 205. Then there is NGC 7603 and NGC 7603B. How about M87 and its jet, known since 1918? And M82 in a region of a large number of high-redshift quasars? And still more are there fantastic shapes and displays of super massive energies. Enough already! The mainstream astronomers wanted Arp forced underground. He surfaced in Germany and San Diego where he continued, as best he could, his research.

Arp was primarily an observer. He established nomenclature. Nevertheless, he endorsed a theory of Hoyle and Narlikar of 1964 that accounted for redshifts as not always involving velocity with special reference to the recessional velocity as evidenced by cosmological redshifts. Hoyle and Narlikar proposed a synthesis of Einstein and Mach. Narlikar and Das in 1980 further refined the theory, one of variable mass. The mass of an electron, for example, depended on how much of the Universe it had interacted with or how long the electron had been in existence. For Arp those intrinsic, discordant redshifts were not dependent on velocity, they are related to time. The redshifts were of the quantum world.


My Notion: Brownian motion can be demonstrated under a microscope with milk diluted with water. The water molecules and their random motion cause "the jitters" for the milk. Suppose the particles of light are like the milk. The quanta units making up the quantum world, not our particle world, are like the water molecules. There is no preferred direction of effect of the quanta on the light unless the direction of travel is in your direction - that confers a preferred direction from your perspective. Remember the spectrum is not the object. The spectrum comes to us over a great amount of time and distance. The quantum bombardment in such a situation alters the energy of the spectra. It makes for a reddening spectra. A snap judgment would be that this is a variant of "tired light". I prefer to call it battered light.










Copyright ©
by Duane Dunkerson

All Rights Reserved
If you wish,
send me
telling me what
you think about
these articles,
etc. Also if
you have a
question relating
to astronomical
matters, I can
answer it
or refer you.



Current Projects

   — TLP
   — Canals of Mars
   — New telescope