Author Topic: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy  (Read 4761 times)

Tony Wei

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Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« on: November 16, 2013, 09:58:23 am »

IC1101(DR10)(largest galaxy known)
I thought of this topic while I was thinking over how big can galaxies be.
These galaxies are really'Leaders' of the galaxies:you can see it from their name--central dominant galaxies.As usual(for me),see some Wiki's info first.
Quote from: Wiki
The type-cD galaxy (also cD-type galaxy, cD galaxy) is a galaxy morphology classification, a subtype of type-D giant elliptical galaxy, and has a large halo of stars. They can be found near the centres of some rich galaxy clusters.They are also known as supergiant ellipticals or central dominant galaxies.

The cD-type is a classification in the Yerkes galaxy classification scheme, one of two Yerkes classifications still in common use, along with D-type. The "c" in "cD" refers to the fact that the galaxies are very large, hence supergiant, while the "D" refers to the fact that the galaxies appear diffuse. A backformation of "cD" is frequently used to mean central Dominant galaxy. cD's are also frequently considered the largest galaxies.
cD galaxies are similar to lenticular galaxies (S0) or elliptical galaxies (E#), but many times larger, some having envelopes that exceed one million light years in radius. They appear elliptical-like, with large low surface brightness envelopes. It is currently thought that cD's are the result of galaxy mergers. Some cD's have multiple galactic nuclei.
You can usually find them in the center of groups of galaxies,they are the rulers,keep the order os clusters.They are real 'Galaxy Kings'.
We are also interested in looking for some interesting features,like jets (M87) and Lens in far groups.


BCGs

PGC 48624(Outside SDSS footprint)


PGC 1981854




Jets

M87




NGC 5128(outside SDSS footprint)




cDs are merger's results

NGC 1275


MACS J0647.8+7015's cD(Outside SDSS's Footprint)



Fat Ones
NGC 6166


NGC 1399 (Outside SDSS Footprint)


NGC 4889&NGC 4874

(4889)
                                                                  (4874)

IC 1565

PGC 2108310





cDs Produce Lens
cD of Abell2218(Outside SDSS footprint)


Abell 1689's cD


RBS 0825



PGC 1360619



MACS 1206's cD(outside SDSS footprint)

PGC 145057


Abell 370's cD



« Last Edit: November 22, 2013, 12:51:09 pm by Tony Wei »
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AlexandredOr

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Re: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« Reply #1 on: November 16, 2013, 01:05:49 pm »
Nice OotD, with great images. Thank you Tony !

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planetaryscience

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Re: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« Reply #2 on: November 16, 2013, 03:51:23 pm »


What kind of lensing did that galaxy at the top left go through? (look to upper right of largest galaxy)

Anyways, great OOTD!  ;D ;D

Here's one:

IC 1565

redshift: 0.037809 (about 500 million light years)
Apparent size: 1.2 by 1.8 arcseconds
Size: How do i calculate this?
I like to find asteroids and galaxy mergers- but all galaxies are still fine to me.

AlexandredOr

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Re: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« Reply #3 on: November 16, 2013, 06:25:11 pm »


What kind of lensing did that galaxy at the top left go through? (look to upper right of largest galaxy)

Anyways, great OOTD!  ;D ;D

Here's one:

IC 1565

redshift: 0.037809 (about 500 million light years)
Apparent size: 1.2 by 1.8 arcseconds
Size: How do i calculate this?

Awesome lensing in the first image.
In the second image you can find the diameter of the galaxy, knowing its distance and its size in arcseconds with the same calculus than the parallaxe : diameter = angular size / distance... unless error  :)

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JeanTate

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Re: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« Reply #4 on: November 16, 2013, 08:11:48 pm »
At HubbleSite, they call this "Gravitational Lens Creates Cartoon of Space Invader"

They identify it - the lens - as the (cD in the) rich cluster Abell 68:

Quote
MARCH 5, 2013: The universe is eerie enough without giving us an apparition of a 1980s video game alien attacker. This oddball-looking object is really a mirage created by the gravitational field of a foreground cluster of galaxies warping space and distorting the background images of more distant galaxies.

This effect, called gravitational lensing, can make multiple mirror image copies of the light coming from a far-flung galaxy. It is a powerful tool for seeing remote galaxies that otherwise would not be observable by Hubble because they are too dim and far away. In this Hubble photo a background spiral galaxy is warped into an image that resembles a cartoon of a simulated space invader. The foreground massive cluster, called Abell 68, lies 2 billion light-years away. The brightened and stretched lensed images come from galaxies far behind it.

Very nice collection of images, Tony!  ;D

c_cld

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Re: Saturday,16th Nov,2013:The Galaxy King--Type-cD galaxy
« Reply #5 on: February 25, 2014, 02:58:13 pm »
started in this thread:
NGC6166 1237659326029365299
with a lot of cross-identifications: ex. ABELL 2199, UGC 10409, 3C 338, ...



Observed in FIRST Radio survey: double lobe


My coadded images:


 8)  8)
« Last Edit: February 25, 2014, 03:00:35 pm by c_cld »