Talk:Centaur (planetoid)

From Wikipedia, the free encyclopedia

	Solar System Portal This article is within the scope of the Solar System WikiProject, a collaborative effort to improve Wikipedia's coverage of the Solar System.
Start	This article has been rated as Start-Class on the assessment scale.

Curps: Good edit on comet/asteroid mixture of 2060 Chiron. It looks like the CFA prefers to list SDOs and Centaurs in reverse chronological order, for some reason. There is a de facto standard for listing objects in Wikipedia in decreasing diameter (see Kuiper belt, Natural satellite, first table in List of noteworthy asteroids) or sometimes chronological order (see second table in List of noteworthy asteroids).. I was trying to not use a third ordering. It would be cool to get diameters on these objects, by the way. -- hike395 05:17, 12 Apr 2004 (UTC)

In this case, I imagined future maintainers of the page would click on the external link to look up any updated info. For lists of more than a few elements, it can be very confusing to compare them if one is in the opposite order of the other (assuming the list on the Wikipedia page might grow considerably). So that's basically the reason I kept it that way. I don't know the diameters of the other objects, maybe the info is out there somewhere. -- Curps 05:45, 12 Apr 2004 (UTC)

That makes sense. -- hike395

Contents 1 Removed to where? 2 Removed line 3 10199 Chariklo 4 Incomplete article 5 Colours 6 lead; Chiron 7 Distinguishing Centaurs from TNOs 8 Centaur list 9 Deleting sections without discussion

[edit] Removed to where?

"Centaurs are not in stable orbits and will eventually be removed by the giant planets." Removed to where? Could someone who knows their stuff clarify this sentence? The Singing Badger 16:15, 26 Sep 2004 (UTC)

Centaurs will be removed from the solar system either by impacting on a planet, perturbed into a sungrazing object and destroyed by impact on or disruption by the sun (like the Kruetz family of Sun-grazing comets) or will be perturbed by one of the planets onto an orbit that will escape the solar system (the most likely removal route...). Most asteroids and Kuiper Belt objects are on orbits which are relatively stable and will last for billions of years, orbiting far enough from the planets so that their orbits will not be drastically perturbed. But in the case of planet crossing asteroids (like Centaurs or Earth-crossing asteroids), the planets (especially Jupiter) will cause drastic changes to the objects orbit, including total ejection from the solar system when the object passes relatively close to the planet in question. Typical dynamical lifetimes of Centaurs are around 1 million to a few 10s of millions of years depending on the specifics of their particular orbit. Jim 00:22, 28 Sep 2004 (UTC)

Cool! That's what I wanted to know. :) The Singing Badger 17:24, 28 Sep 2004 (UTC)

[edit] Removed line

"In 2010, the New Horizons spacecraft is expected to perform a distant flyby of a centaur, (83982) 2002 GO₉."

This statement was earlier removed from the New Horizons article and appears to untrue/speculation. Rmhermen 19:14, 17 January 2006 (UTC)

[edit] 10199 Chariklo

I got rid of the ugly red link to 10199 Chariklo in the "notable centaurs" section. I wasn't sure how much information on centaurs is appropriate to add there, so any input would be appreciated! shaggy 23:07, 1 March 2006 (UTC)

Yes, I believe that while the articles related to TNO/Centaurs are growing in substance we should review the distribution of the content among different articles to allow a logical, progressive digging into details while providing a quick essential read to a casual visitor. An experienced editor with not too much background in the subject would be the best, IMHO. As examples of simple common sense rules could be: let’s do not make the reader to open the link just to read the definition. Another one: if the diameter is say: 300km, let’s be nice and add whether it is huge or small for the given class of objects. Eurocommuter 11:00, 2 March 2006 (UTC)

I think some of the more well-done KBO articles could be a good model for this. The really important things to cover (and for many of these objects, the only information available) are things like the date of it's discovery, where it orbits, and (usually) color data is pretty easy to find. 90482 Orcus is a pretty good example, I think, of a non-stub outer solar system minor planet article. shaggy 15:14, 2 March 2006 (UTC)

[edit] Incomplete article

This article could be expanded to include data about the color of Centaurs. Also, there's no mention of the relationship between centaurs and the Scattered Disc. Other articles on KBOs reference the "red color of KBOs and Centaurs", so there's gotta be a source for this information on wikipedia already. I would fix it now, but I don't have time. shaggy 15:18, 2 March 2006 (UTC)

Indeed. I’m collecting some references to the articles on colour for TNO. I’ve got only tangent interest in colour, in relation to the models of the origin and classification of TNO/centaurs but I’ll be hopefully extending this aspect in the near future. TNO/centaur connection is an interesting one and so far underexposed in our articles. Eurocommuter 17:15, 2 March 2006 (UTC)

Also, a table of notable Centaurs similar to the list at Kuiper belt would be an excellent addition. shaggy 19:47, 2 March 2006 (UTC)

[edit] Colours

Is the colour section misleading to the layman? When a Centaur is described as "intensely red" do we mean that literally, or do we mean it's intense when compared to other astronomical bodies? Also, the diagram of colours shows bright purple Centaurs. Surely they're not really as purple as that? Any suggestions for how to make this clearer? The Singing Badger 12:52, 14 March 2006 (UTC)

I understand that broadband colour indices are not equivalent of three monochromatic pictures to be combined into a natural colour, as for the fantastic satellites’ pictures for example. I have a problem how to expression the colours and perhaps I’ve exaggerated (a bit?). The problem is not simple (see colour related articles). I did indeed enhance the colours to make the point and avoid dim, dirty spheres by aligning the luminosity and ignoring the albedo. (Albedo is known only for a few of them, anyway). Pholus is indeed the most red observed object (quoted refs). I’m not so bothered with the purple, it is after all on blue/red diagonal, but I should probably add more green to have the blue less blue and more grey/blue. Please consider this as a draft. I’ll be most grateful for any technical note how to combine V-B and R-V into RGB (you probably see different colours on your monitor than me, anyway). Eurocommuter 14:06, 14 March 2006 (UTC)

I think saying that the colours are enhanced is all that is necessary. It looks better already. I'm afraid I can't help with the technical side. :( The Singing Badger 14:33, 14 March 2006 (UTC)

Well, in addition to the voluntary enhancement I found a program bug shifting the colours into hellish hues. I discovered it while my rendering of Pluto did not want to match Nasa’s idea of the hue. My apologies Eurocommuter 22:49, 16 March 2006 (UTC)

looks much better now. I could almost believe those are the actual colors! Are you working on similar diagrams for the other TNO groups? shaggy 23:57, 16 March 2006 (UTC)

[edit] lead; Chiron

Mentioning Chiron’s double life as a comet so early in the lead bothers me a lot, as it could mislead into thinking that cometary activity is typical for centaurs. (maybe it is but yet to be observed for others). Perhaps we should move it into a small subsection, further on. Eurocommuter 13:50, 14 March 2006 (UTC)

I was thinking of trying to fit it into the physical characteristics section later today. It's really the only place I could think of to move it. I did substantially re-organize 2060 Chiron earlier, so we might think about moving most of that information over there. shaggy 13:59, 14 March 2006 (UTC)

Looking at it more, I think this is now one of the worst leads I have ever seen on wikipedia. I'm gonna take a crack at re-writing it. shaggy 20:09, 15 March 2006 (UTC)

[edit] Distinguishing Centaurs from TNOs

I'm wondering about the classification of the distant bodies in Image:TheKuiperBelt_55AU_Centaurs.svg as Centaurs. (The ones that cluster just inwards of the plutinos). A lot of them look rather like TNOs to me -- They don't even cross Neptune's orbit. Take, for example, 2004 TY₃₆₄. While there is apparently no agreed-upon definition of what is a centaur and what isn't, I would have thought that you at least should be within Neptune's orbit some of the time, otherwise you're obviously a trans-neptunian object. Is some other definition being used? Deuar 10:16, 27 March 2006 (UTC)

That’s an old graph…(lame excuse).Good point; I promise to check; having a heavy week in real life but I’ll look into it on Saturday. My program(s) is taking the data from MPCORB database. Back then, I did not have a module checking and correcting the types with the current MPC circular for the orbit classification (as I do now, for example in the case of the orbit plots for plutinos). I will re-generate this diagram with the current modules.Eurocommuter 18:46, 28 March 2006 (UTC)

Indeed, MPCORB (the database, not html on the Web) lists 2004 TY₃₆₄ as Centaur (type 10 in column 162-165 as per format description. The MPC Circular X77 I have used for other graphs does not qualify the orbit, by the way. My program followed MPC type qualification (blame yours truly, not the poor Java). As per consensual no-nonsense definition, centaurs orbits have a_Centaur < a_Neptune. My apologies. Thanks Peter! Will be fixed. Eurocommuter 20:09, 29 March 2006 (UTC)

Funny MPCORB qualified it that way. I seem to recall they mentioned in a summary sheet somewhere that the flags they have are not to be trusted, but I didn't really believe that before ;-) This is fun isn't it! Deuar 21:40, 29 March 2006 (UTC)

Fixed this one but a few others are affected as well.Eurocommuter 06:33, 30 March 2006 (UTC)

Looks good. I hadn't realised that Pholus is also bigger than Chiron. Deuar 10:27, 30 March 2006 (UTC)

See Talk:trans-Neptunian object#The objects between Neptune and Pluto for further discussion. Eurocommuter 11:02, 1 April 2006 (UTC)

[edit] Centaur list

Hello Centaur enthusiasts ...... I've been studying the IAU list of Scattered Disk Objects and Centaurs, and am wondering how to tell which is which! Does anyone know the location of a simpler list which clearly designates information about ONLY Centaurs, whether officially named or not? Would be much appreciated. Thanks.

Later + more searching. Check out www.zanestein.com for some great lists of information.

C'mon, that's an astrology page.

Anyway, a rough rule of thumb for Centaurs is that their semi-major axis is smaller than Neptune's. Deuar 18:09, 14 October 2006 (UTC)

You might try the JPL Small-Body Database Search Engine and specify: "Constraints: orbital class (CEN) and q > 5.5 (AU) and a < 29.7 (AU)". I came up with 64 matches.
1. Under "Limit to selected orbit class(es):" Put a check on Centaur.
2. Use the 2nd pull down to select "q (au)" > 5.5 (Aph-Jup) and click Add.
3. Use the 2nd pull down to select "a (au)" < 29.7 (Peri-Nept) and click Add.
4. Under "Pre-defined field sets:" select "Asteroid - Basic" and click "Append Selected".
5. Under Table Format, select "50 rows per page max."
6. Click "Generate Table".
You can tweak the options as you get use to using it.
Kheider 08:42, 19 October 2007 (UTC)

[edit] Deleting sections without discussion

I would like to see discussions before whole sections are deleted just because there are no citations. -- Kheider 06:27, 10 October 2007 (UTC)

The editor, Daniel Bush, made similar changes at Neptune, Asteroid, Ceres, and Small Solar System Body. He's been asked to explain these edits. --Ckatz^chat_spy 07:10, 10 October 2007 (UTC)