APOD: The Perseus Cluster of Galaxies (2011 Jul 12)

[APOD Robot]

The Perseus Cluster of Galaxies

Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen above as a large galaxy on the image left. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies, also cataloged as Abell 426, is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies. At the distance of NGC 1275, this view covers about 15 million light-years.

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[/b]

[islader2]

A true astronomy picture. APOD delivers often=such as this posting. I like it!

[neufer]

Click to view full size image

The Nearest Superclusters

<<This is a map of the universe within 500 million light years. It shows most of the major galaxy superclusters that surround the Virgo supercluster. These superclusters are not isolated in space but together with many other smaller concentrations of galaxies they form parts of extensive walls of galaxies surrounding large voids. Three of the biggest walls near us are marked on the map as well as several of the largest voids. There are several hundred thousand large galaxies within 500 million light years, so even on this scale our galaxy is a very insignificant object.>>

[Beyond]

Galaxies-Galaxies-everywhere, but not an alien in sight. Kinda like floating on a raft out in the ocean; water-water-everywhere, but not a drop to drink.

[Ann]

Like most galaxies belonging to rich clusters, the galaxies in the Perseus cluster have mostly hit the snooze button and gone to sleep:

Click to view full size image

For a galaxy, "going to sleep" means that it stops producing stars. According to a recent survey most galaxies throughout the universe are actively producing stars, but as early on in the history of the universe as 12 billion years ago, some galaxies had already "fallen asleep" and stopped making youngsters. Read about it here: http://www.astronomynow.com/news/n1107/05galaxy/

One sure way to make galaxies stop producing stars appears to be to crowd them together in large clusters. Typically, galaxy clusters - and especially dense clusters - are totally dominated by elliptical galaxies, those that have "hit the snooze button" and stopped producing stars. (Admittedly it has recently been shown that "dead" or "sleeping" galaxies may not be "totally dead" after all, only nearly so. See http://asterisk.apod.com/viewtopic.php?f=31&t=23830. These "dead" galaxies that manage to churn out a few new stars after all do so extremely slowly, at least 50 times more slowly than active, "wakeful" galaxies according to the survey I mentioned above.)

One sure way to stop star formation appears to be to have too many collisions and interactions between galaxies, which is going to be extremely common in dense clusters. Check out the many yellowish rather shapeless blobs in today's APOD. They are ellipticals and lenticulars, galaxies made up of old stars. But occasionally, when the major galaxies of a whole clusters have shut down their star formation and turned into ellipticals, a monster elliptical galaxy may get to munch on an unusually rich tidbit of gas. This leads to a (local) torrent of starbirth and to major outbursts from the black hole of the large elliptical galaxy:

Click to view full size image

This is Perseus A, the dominant galaxy in the Perseus cluster, the cluster featured in today's APOD. Perseus A, also known as NGC 1275, is still in the process of feasting on a small spiral galaxy. Many new stars have formed as the hapless spiral is being digested by the monster elliptical, and the elliptical itself is burping most violently as it suffers from indigestion. Image credit: NASA.



Indigestion, indeed. Note the small blue arm of the spiral galaxy sticking out near the center of this chaos caused by the black hole of Perseus A. Image credit: Chandra X-ray Observatory.

By the way, where is Perseus A in today's APOD? It is the large galaxy at far left. You can see that its color sets it apart from the other ellipticals, because while the other ellipticals are yellow, Perseus A also glows red from hydrogen alpha emission and blue from the light of young stars. But Perseus A also contains billions and trillions of small yellow-orange stars which contribute to the overall color of this fascinating galaxy.

Ann

[techlady911]

What are the two bright blue objects just to the upper right of center in this photo?

[orin stepanek]

Two of the links didn't work for me.!

Perseus Cluster, one of the closest clusters of galaxies.

[owlice]

Orin, thanks; I've sent a note to the editor.

And your post was post number 76667, which is a beastly palindromic prime number.

[orin stepanek]

Orin, thanks; I've sent a note to the editor.

And your post was post number 76667, which is a beastly palindromic prime number.

Wow! Cool! http://en.wikipedia.org/wiki/Palindromic_number You threw a big word at me!

[hpfeil]

> What are the two bright blue objects just to the upper right of center in this photo?
This ignorant fool suggests that the blue stars with CCD spikes are within the Milky Way galaxy, judging by past APODs.

[neufer]

---

This is Perseus A, the dominant galaxy in the Perseus cluster, the cluster featured in today's APOD. Perseus A, also known as NGC 1275, is still in the process of feasting on a small spiral galaxy. Many new stars have formed as the hapless spiral is being digested by the monster elliptical, and the elliptical itself is burping most violently as it suffers from indigestion. Image credit: NASA.

[b][color=#0000FF]Hubble Space Telescope image of the center of NGC 1275[/color][/b]

---

<<NGC 1275 consists of two galaxies, the central CD Galaxy in the Perseus Cluster, and the so-called "high velocity system" (HVS) which lies in front of it. The HVS is moving at 3000 km/s towards the dominant system, and is believed to be merging with the Perseus Cluster. The HVS is not affecting the CD Galaxy as it lies at least 200 thousand light years from it.

The central cluster galaxy contains a massive network of spectral line emitting filaments, which appear to be being dragged out by rising bubbles of relativistic plasma generated by the central active galactic nucleus. Long gaseous filaments made up of threads of gas stretch out beyond the galaxy, into the multimillion-degree, X-ray–emitting gas that fills the cluster. The amount of gas contained in a typical thread is approximately one million times the mass of our own Sun. They are only 200 light-years wide, are often very straight, and extend for up to 20,000 light-years. The existence of the filaments poses a problem. As they are much cooler than the surrounding intergalactic cloud, how have they persisted for perhaps 100 million years? Why haven’t they warmed, dissipated or collapsed to form stars? One possibility is that weak magnetic fields (about one-ten-thousandth the strength of Earth’s field) exert enough force on the ions within the threads to keep them together.>>

[neufer]

> What are the two bright blue objects just to the upper right of center in this photo?

This ignorant fool suggests that the blue stars with CCD spikes are within the Milky Way galaxy, judging by past APODs.

• 1) Diffraction spikes are optical artifacts of the aperture and have nothing to do with the sensor itself.
  
  2) "IMHO" (or such) is preferable to "this ignorant fool" since:
  
  • a) It was not at first clear to whom were referring.
    
    b) It is still not clear that you aren't implying that it was a foolish question to begin with.

[Axel]

Most galaxies in the image - not all of course - seem roughly positioned along a line: I immediately thought of a sort of ecliptic. Might the "walls" of galaxies be due to some gravitational effect making objects tend to move around a common plane?

[neufer]

Most galaxies in the image - not all of course - seem roughly positioned along a line: I immediately thought of a sort of ecliptic. Might the "walls" of galaxies be due to some gravitational effect making objects tend to move around a common plane?

Concentrations of positive mass (i.e., high amounts of dark matter) will pull matter together but only after overcoming centrifugal forces (possibly leading to flattened sheets of matter).

However, it is much simpler to think in the reverse:

Concentrations of negative mass (i.e., low amounts of dark matter) will push matter apart without having to overcome any centrifugal forces thereby leading to: "a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes."

<<Sky surveys and mappings of the various wavelength bands of electromagnetic radiation (in particular 21-cm emission) have yielded much information on the content and character of the universe's structure. The organization of structure appears to follow as a hierarchical model with organization up to the scale of superclusters and filaments. Larger than this, there seems to be no continued structure, a phenomenon which has been referred to as the End of Greatness.

DTFE reconstruction of the inner parts of the 2dF Galaxy Redshift Survey

---

The organization of structure arguably begins at the stellar level, though most cosmologists rarely address astrophysics on that scale. Stars are organized into galaxies, which in turn form clusters and superclusters that are separated by immense voids, creating a vast foam-like structure sometimes called the "cosmic web". Prior to 1989, it was commonly assumed that virialized galaxy clusters were the largest structures in existence, and that they were distributed more or less uniformly throughout the universe in every direction. However, based on redshift survey data, in 1989 Margaret Geller and John Huchra discovered the "Great Wall", a sheet of galaxies more than 500 million light-years long and 200 million wide, but only 15 million light-years thick. The existence of this structure escaped notice for so long because it requires locating the position of galaxies in three dimensions, which involves combining location information about the galaxies with distance information from redshifts. In April 2003, another large-scale structure was discovered, the Sloan Great Wall. In August 2007, a possible supervoid was detected in the constellation Eridanus. It coincides with the 'WMAP Cold Spot', a cold region in the microwave sky that is highly improbable under the currently favored cosmological model. This supervoid could cause the cold spot, but to do so it would have to be improbably big, possibly a billion light-years across.

In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes. This network is clearly visible in the 2dF Galaxy Redshift Survey. In the figure a 3-D reconstruction of the inner parts of the survey is shown, revealing an impressive view on the cosmic structures in the nearby universe. Several superclusters stand out, such as the Sloan Great Wall, the largest structure in the universe known to date.>>

[BMAONE23]

What are the two bright blue objects just to the upper right of center in this photo?

The two bright blue objects with the diffraction spikes are stars in our own galaxy

[neufer]

What are the two bright blue objects just to the upper right of center in this photo?

The two bright blue objects with the diffraction spikes are stars in our own galaxy

All three of the right triangle objects are overexposed 11th magnitude stars in our own galaxy:

• 1) TYC 2856-1642-1: Mag. 11.079
  2) HD 275047: Mag. 11.227
  3) TYC 2856-560-1: Mag. 11.331

NGC 1275 has an apparent magnitude of 12.6.

[moikey@att.net]

Interesting how the stars disappear from the x-ray view.

[Ann]

neufer wrote:

All three of the right triangle objects are overexposed 11th magnitude stars in our own galaxy:

1) TYC 2856-1642-1: Mag. 11.079
2) HD 275047: Mag. 11.227
3) TYC 2856-560-1: Mag. 11.331

TYC 2856 1642 has a VT magnitude of 11.102 ± 0.072 and a B-V index of +0.233 ± 0.01. Its parallax, as measured by Tycho, is -19 ± 43 milliarcseconds. Since negative parallaxes don't exist, this measurement is clearly not correct, but it definitely suggests that the star is not nearby. Compare it with Proxima Centauri, which is the most nearby of all stars except the Sun. The VT magnitude of Proxima Centauri is 11.01 and its parallax is +772 ± 2.42 milliarcseconds, which corresponds to a distance of 4.223 ± 0.013 light-years. The B-V index of Proxima is +1.807 ± 0.020. The spectral class of Proxima is M5V and its luminosity is 0.00005500 ± 0.00000034 times that of the Sun.

Compared with Proxima, we can see that TYC 2856 1642 is about the same apparent magnitude, but because of its tiny parallax we can be sure that it is vastly farther away than four light-years. Therefore it is much, much brighter than Proxima. In fact, because the star is a lot bluer than the Sun while at the same time it is quite far away and still as bright as eleventh magnitude, we can be sure that the star is both hotter and brighter than the Sun. Its color corresponds to a main sequence star of spectral class A7 like famous and nearby Altair, alpha star of the constellation of Aquila, whose parallax of +194.44 ± 0.94 milliarcseconds corresponds to a distance of 16.774 ± 0.081 light-years, and whose luminosity is 10.93 ± 0.11 times that of the Sun.

TYC 2856 1642 is clearly a lot farther away than Altair. That suggests that its intrinsic color may well be bluer than +0.233 ± 0.01, because it is quite likely that the star is noticably reddened by intervening dust. That in turn suggests that TYC 2856 1642 is hotter and therefore almost certainly brighter than Altair. We don't know how reddened TYC 2856 1642 is, but we can say with considerable certainty that the minimum brightness of this star is about 11 times that of the Sun, like Altair, and we can say with even greater certainty that its minimum temperature is 7550 Kelvin, also like Altair.

As for the two other stars, TYC 2856 560 has a B-V index of +0.689 ± 0.136. This corresponds to a temperature very much like the temperature of the Sun, which is 5800 Kelvin, resulting in a B-V index of 0.656±0.005. TYC 2856 560 may be similar to the Sun, but if it is reddened by intervening dust it may well be intrinsically hotter and brighter than our own star. No parallax is given for TYC 2856 560.

As for HD 275047, it too has a "false negative" parallax, and it too is probably quite far away. Its B-V index, +0.031 ± 0.085, corresponds to an early A-type star, not unlike Sirius. Sirius is 21.79 ± 0.18 times brighter than the Sun, and we can be reasonably certain that HD 275047 is at least as bright as that. But HD 275047 could be reddened by dust due to its possibly great distance from us, in which case it might be considerbly hotter and brighter than Sirius.

All in all, I'd say that at least two of the three bright stars in today's APOD are really intrinsically blue. The third one might be either intrinsically blue or intrinsically white, like the Sun.

Ann

[saturn2]

The Pisces-Perseus Supercluster has over 1000 galaxies.
Here is the Perseus Cluster.
Distance of center of this cluster 250 million light years ( approximately).
In the Universe the distances are very great. For example, the distance from Earth to Coma Supercluster is 370 million light years.

[Ann]

Owlice wrote:

And your post was post number 76667, which is a beastly palindromic prime number.

http://en.wikipedia.org/wiki/The_Man_Wh ... _for_a_Hat wrote:

The Man Who Mistook His Wife for a Hat and Other Clinical Tales is a 1985 book by neurologist Oliver Sacks describing the case histories of some of his patients.

The book comprises 24 essays split into 4 sections which each deal with a particular aspect of brain function such as deficits and excesses in the first two sections (with particular emphasis on the right hemisphere of the brain) while the third and fourth describe phenomenological manifestations with reference to spontaneous reminiscences, altered perceptions, and extraordinary qualities of mind found in retardates.

The individual essays in this book include, but are not limited to:

"The Twins," about autistic savants. Dr. Sacks meets twin brothers who can neither read nor perform multiplication, yet are playing a "game" of finding very large prime numbers. While the twins were able to spontaneously generate these numbers, from six to twenty digits, Sacks had to resort to a book of prime numbers to join in with them. This was used in the film House of Cards starring Tommy Lee Jones. The twins also instantly count 111 dropped matches, simultaneously remarking that 111 is three 37s. This event, with toothpicks in place of matches,[4] was used in the film Rain Man, starring Dustin Hoffman.

http://en.wikipedia.org/wiki/Palindrome wrote:

A palindrome is a word, phrase, number or other sequence of units that can be read the same way in either direction (the adjustment of punctuation and spaces between words is generally permitted).

Palindromes date back at least to 79 AD, as the palindromic Latin word square "Sator Arepo Tenet Opera Rotas" (The sower, Arepo, holds works wheels) was found as a graffito at Herculaneum, buried by ash in that year. This palindrome is remarkable for the fact that it also reproduces itself if one forms a word from the first letters, then the second letters and so forth. Hence, it can be arranged into a word square that reads in four different ways: horizontally or vertically from either top left to bottom right or bottom right to top left.

Ann

[Axel]

Most galaxies in the image - not all of course - seem roughly positioned along a line: I immediately thought of a sort of ecliptic. Might the "walls" of galaxies be due to some gravitational effect making objects tend to move around a common plane?

Concentrations of positive mass (i.e., high amounts of dark matter) will pull matter together but only after overcoming centrifugal forces (possibly leading to flattened sheets of matter).

However, it is much simpler to think in the reverse:

Concentrations of negative mass (i.e., low amounts of dark matter) will push matter apart without having to overcome any centrifugal forces thereby leading to: "a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes."

<<Sky surveys and mappings of the various wavelength bands of electromagnetic radiation (in particular 21-cm emission) have yielded much information on the content and character of the universe's structure. The organization of structure appears to follow as a hierarchical model with organization up to the scale of superclusters and filaments. Larger than this, there seems to be no continued structure, a phenomenon which has been referred to as the End of Greatness.

DTFE reconstruction of the inner parts of the 2dF Galaxy Redshift Survey

---

The organization of structure arguably begins at the stellar level, though most cosmologists rarely address astrophysics on that scale. Stars are organized into galaxies, which in turn form clusters and superclusters that are separated by immense voids, creating a vast foam-like structure sometimes called the "cosmic web". Prior to 1989, it was commonly assumed that virialized galaxy clusters were the largest structures in existence, and that they were distributed more or less uniformly throughout the universe in every direction. However, based on redshift survey data, in 1989 Margaret Geller and John Huchra discovered the "Great Wall", a sheet of galaxies more than 500 million light-years long and 200 million wide, but only 15 million light-years thick. The existence of this structure escaped notice for so long because it requires locating the position of galaxies in three dimensions, which involves combining location information about the galaxies with distance information from redshifts. In April 2003, another large-scale structure was discovered, the Sloan Great Wall. In August 2007, a possible supervoid was detected in the constellation Eridanus. It coincides with the 'WMAP Cold Spot', a cold region in the microwave sky that is highly improbable under the currently favored cosmological model. This supervoid could cause the cold spot, but to do so it would have to be improbably big, possibly a billion light-years across.

In more recent studies the universe appears as a collection of giant bubble-like voids separated by sheets and filaments of galaxies, with the superclusters appearing as occasional relatively dense nodes. This network is clearly visible in the 2dF Galaxy Redshift Survey. In the figure a 3-D reconstruction of the inner parts of the survey is shown, revealing an impressive view on the cosmic structures in the nearby universe. Several superclusters stand out, such as the Sloan Great Wall, the largest structure in the universe known to date.>>

Except for the first sentence, none of this says that a concentration of galaxies must form along a plane or other surface-like form. And as for the more or less straight line in the picture suggesting that a large number of the Perseus galaxies lie approximately on a plane, I can't assume that this phenomenon is related to the vast galaxy superclusters. But thanks for this informative response.

[neufer]

Orin, thanks; and your post was post number 76667, which is a beastly palindromic prime number.

• Mexia, Texas
  ZIP code 76667

<<Mexia (mə-hay-ə or mə-hair) is a city in Limestone County, Texas, United States, population 6,552. The city's motto, based on the fact that outsiders tend to mispronounce the name [ˈmɛksiə], is "A great place, no matter how you pronounce it."

Martin: I hope you die!
Ethan (Wayne): That'll be the day.

Named after General José Antonio Mexía, a Hispanic hero for the Republic of Texas Army during the Texas Revolution, the town was founded near his estate. Nearby attractions include Mexia State Supported Living Center, which began as a prisoner of war camp for members of Field Marshal Erwin Rommel's Afrika Korps during World War II. Mexia is also home to the Mexia Public Schools Museum, one of a few museums dedicated to the historical and social significance of a Texas public school system. Mexia hosts a large Juneteenth celebration every year commemorating the abolition of slavery in the U.S. State of Texas in 1865.

In the 19th century the Comanche tribe came into conflict with the white settlers in and around this area. Comanches raided the Fort Parker and left with the three year old girl. Cynthia Ann Parker lived among the Comanche people into adulthood and was the mother of Quanah Parker, the last Comanche war chief.

When Vickie Lynn Hogan (a.k.a., Anna Nicole Smith) was in the 9th grade, she was sent to live with her mother's sister, Kay Beall, in Mexia. At Mexia High School, Anna Nicole failed her freshman year and later quit school during her sophomore year. While working at Jim's Krispy Fried Chicken in Mexia, Anna Nicole met Billy Wayne Smith, who was a cook at the restaurant. The couple married April 4, 1985; when she was 17 and he was 16. Anna Nicole gave birth to their son, Daniel Wayne Smith on January 22, 1986. She and Billy separated in 1987 and she moved to Houston where Anna Nicole found employment at Wal-Mart, then as a waitress at Red Lobster. She then became a stripper.>>

[Beyond]

She then became a stripper.

The rest, as they say, is Herstory.

[neufer]

She then became a stripper.

The rest, as they say, is Herstory.

That'll be the day.

[Beyond]

She then became a stripper.

The rest, as they say, is Herstory.

That'll be the day.

Alas....that day has come and gone.