Sometimes a galaxy has characteristics of several types of galaxies.
So it isn't so easy.
Look at its spectral chart. For help see Zooite Guide to Spectra
Look at the "white pea".587731680116867174
The colours in the images are in these areas on the chart
| blue light |
| green light |
| red light |
|This "white pea" has a blue rise at 4000 Å and a small blue OII peak,|
and a green OIII peak
Normally, this would make a green pea.
But the nucleus is active, making a Hα peak in the red.
So, blue + green + red = white
Looking at some other examples
|This is a star-forming galaxy, making blue light. It would have a yellow nucleus (yellow is green+red)|
But the nucleus is also a blue pea, as seen by the OIII peak in the blue area of the spectrum. So the nucleus is white (white=blue+green+red)
This should be a blue compact galaxy, but it has an active nucleus, adding red to make a purple colour
posted by c_cld
|This should be a green pea (OIII peak in green) , but it has an active nucleus (Hα peak in the red), so it is yellow. (green+red=yellow)|
|This is a green starburst, but it has an active nucleus (red), so it becomes yellow (green+red=yellow)|
posted by LizPeter
|This should be a magenta quasar (blue rise at 4000 + red Hα peak), but it is also a green pea, so it is white (green+blue+red=white)|
|This should be a blue quasar (blue rise at 40000), but it is also a red pea, so it is magenta (blue + red), also called purple, or sometimes pink|
|This is mostly a blue quasar, but it is also an ageing starburst, which adds a red colour to make magenta|
posted by c_cld
Then just when you think it starts to make sense, seewaveneys red spirals and blue ellipticals
For suggestions to changes to this chart, see Colours of Galaxies : Redshift chart suggestions on the Suggestions and Comments thread http://www.galaxyzooforum.org/index.php?topic=277143.0
Almost all the examples posted have a spectrum available.
Information on spectral charts is at Zooite Guide to Spectra
Do you want easy answers to a spectrum question? See Newbies, post your spectrum questions here
Do you want exact answere to a spectrum question? See Tutorial bits on galaxy spectra
Other colour chartsliathro's colour survey (peas) liathro's A little previously unknown objects gallery OOTD Fri Jan 19 2009 Rick Nowells Markarian peas montageRedshift Gallery: Quasars
Lists of objects (have I missed any?)starry nite's OIII galaxy cataloglianthro's OIII object categories pea chartRick Nowell list of ccardamone's peas for the publicationRick Nowells list of Markarians Rick Nowells list of Wolf-Rayets
I can't take much credit for the chart: it is the work of thousands of Zooites.
Thank you to the Zooites who posted objects on the forum, all pretty and organized, so all I had to do was choose examples.
Thank you to the Zooites and astronomers who took time to share their knowledge,
and the moderators, and ZooKeepers, and SDSS for the images.
This chart was created when Galaxy Zoo 2 was using SDSS data.
It will not work for Hubble Zoo.
Here is a written chart
Different types of galaxies have different colours.
The colour of the galaxy changes with distance away (redshift) too.
Here is a table arranged by the type of object, and distance.
The types of objects are:
ellipticals - produce white light, from white stars
spirals - produce blue light from blue stars
compacts - produce ultraviolet light (UV) from young stars (star-forming galaxies)
OIII objects - produce emission lines from hot oxygen
active nuceus - produce emission lines from hot hydrogen
Galaxies that have several of these characteristics are discussed at the end. redshift table for colours of galaxies
|redshift||Million ||ellipticals ||spirals ||star-forming ||oxygen emission ||hydrogen emission|
| z||light-year||white ||blue ||ultra-violet || OIII||Hα|
| 0 || 0||white stars||blue stars||young stars||blue nebulae||green nebulae|
| .001|| 14||ellipticals||blue arms||blue compact||OIII regions||green emissions|
| 0.01 || 137||ellipticals||blue spirals||blue compact||OIII regions||green nucleus|
| 0.02 || 272||ellipticals||blue spirals||blue compact||blue peas||green nucleus|
| 0.03 || 405||ellipticals||blue spirals||blue compact||blue peas||magenta nucleus|
| 0.04 || 536||ellipticals||blue spirals||blue compact||blue peas||magenta nucleus|
| 0.05 || 665||ellipticals||blue spirals||blue compact||purple peas||magenta nucleus|
| 0.06 || 793||ellipticals||blue spirals||blue compact||purple peas||magenta nucleus|
| 0.07 || 919||ellipticals||blue spirals||blue compact||purple peas||magenta nucleus|
| 0.08 || 1040||ellipticals||blue spirals||blue compact||purple peas||magenta nucleus|
| 0.09 || 1170||ellipticals||blue spirals||blue compact||purple peas||magenta nucleus|
| 0.1 || 1290||yellow blobs||blue spirals||blue compact||white/green peas ||magenta quasars|
| 0.2 || 2410||yellow blobs||blue spirals||white compact||green peas||white quasars|
| 0.3 || 3390||yellow blobs||blue smudge||green starburst||green peas||white quasars|
| 0.4 || 4260||yellow blobs||green smudge||green starburst||yellow peas||blue quasars|
| 0.5 || 5020||orange blobs||green smudge||yellow starburst||red peas||blue quasars|
| 0.6 || 5690||red blobs||yellow smudge||red starburst||red peas||blue quasars|
| 0.7 || 6290||red blobs||red smudge||magenta starbust||red peas||blue quasars|
| 0.8 || 6830||red blobs||red smudge||magenta starburst||red peas||blue quasars|
| 0.9 || 7300||red blobs||red smudge ||magenta starburst||red peas||blue quasars|
| 1.0 || 7730||smudge||white starburst||magenta quasars|
| 2.0 || 10300|| ||white starburst||blue quasars|
| 3.0 || 11500|| ||white starburst||blue quasars|
| 4.0 || 12100|| ||green quasars|
| 5.0 || 12500|| ||red quasars|
| 6.0 || 12700||..........||..........||..........||..........||..........|
SDSS colours are used color explanatation by laithro, starry nite and FermatsBrothersDescriptions of unusual types of galaxies
|1089 || 13770||Cosmic Microwave Background (CMB)|
| ∞ || 13770|| Big Bang|