Talk:Red dwarf

message: Stars of extremely high mass that burned out quickly, by cosmological standards, and thereby created all the metals needed for the current crop of Population II and Population I stars. Shouldn't this have left us with a very high number of neutron stars, magnetars, and black holes? Wouldn't the consequences of having a large number of such objects around be rather serious?
Here, I am not criticizing Wikipedia as this seems to be an accurate exposition of current theory. Nevertheless, I do have serious misgivings about the theory. Granted, Astronomers, Astrophysicists, and Comologists need a theory to work with and from, but they seem terribly cocksure at times.
Quoting the article on Pop III stars here, because I cannot get the talk tab to work on that article:
"If these stars were able to form properly, their lifespan would be extremely short, certainly less than one million years. As they can no longer form today, viewing one would require us to look to the very edges of the observable universe. (Since the time it takes light to reach Earth from great distances is extremely long, it is possile to see "back in time" by looking farther away.) Seeing this distance while still being able to resolve a star could prove difficult even for the James Webb Space Telescope."
If the theory concerning these putative stars is in any way correct, then JWST should be able to view entire galaxies of such stars, yes? The spectra of nearly all the stars should all be very nearly the same, depending upon the age of the putative galaxies of Pop III stars. In fact I would expect the spectra of such young galaxies to fall into "bins" according to their ages. A galaxy only one million years old should be easily distinguishable from one that is slightly older than one million years and so on until all the Pop III stars have had time to burn out. Metalicity galaxy wide should increase with age in almost stair-step fashion.
It amazes me, by the way, that something around one percent or less of elements heavier than helium can have such profound effects on stellar size. Current counts suggest that the overwhelming majority of Pop II and Pop I stars are K to M class dwarfs. Why the anticipated paucity of such stars in Pop III? Simply because we have not found any such stars that have turned off the main sequence?
Personally, I think it is more likely that we have not found them because they are dim and we have not devoted enough instrument time to look for them. But, then again, perhaps the black holes gobbled them up.
70.116.68.198 06:56, 1 January 2006 (UTC)
thread_title:  Population III stars. 

message: Here is a very useful link:
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v540n1/50350/50350.html
Somewhere along the way, their simulation runs must have butted heads with Xeno of Elea. They assume the existence of "dark matter" and a considerably less than homogenous cloud structure in the "early universe."
There is no suggestion that any non-linear, self-iterative processes were considered. Such large clouds of gasses would necessarily be affected by such processes. Quoting the above linked article:
"What will be the fate of the collapsing core? Within the core the number densities increase from 105 to 108 cm-3. For densities ≳108 cm-3, however, three-body formation of H2 will become the dominant formation mechanism, transforming all hydrogen into its molecular form (Palla et al. 1983). Our chemical reaction network does not include this reaction, and the solution cannot be correct at r ≲ 0.1 pc. The most interesting effect of the three-body reaction is that it will increase the cooling rate by a factor of ∼103, leading to a further dramatic density enhancement within the core. This will decrease the dynamical timescales to ≪100 yr, effectively decoupling the evolution of the fragment from the evolution of its host primordial molecular cloud. Therefore, it is a firm conclusion that only the gas within these cores can participate in Population III star formation."
The model used relies non-local thermodynamic equilibrium and this can be problematic.
http://www.physics.usyd.edu.au/astron/iau189/toc-posters.ps
Also, the one description of the nucleosynthesis process in Population III stars that I could access assumes that the stars are not rotating.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v567n1/54373/54373.text.html?erFrom=-7768877433592011253Guest
The upshot is that we appear to be placing a wee bit too much faith in a computing model limited by computing resources, particularly when it is claimed that only very large stars (30 to 1000 solar masses) were made during this period of cosmological history and that none of those stars were in rotation.
While this IS a good working theory on which to foot further investigations, the investigators seem to be entirely too eager to comply with pre-conceived notions. In court they would be accused of "assuming facts not in evidence." Rather than being an effort to discover the nature of stars that formed during the early periods of the universe, assuming the universe had an "early period", this seems to be an attempt to shore up a problem ridden model of the universe.
The current cosmological model may one day be shown to be correct, but dogmatic adherence to it prior to such a demonstration strikes me as being a very poor procedure. While a sincere search for very old red dwarfs or K stars of Population III origin would be arduous, it should nevertheless be carried out.
70.116.68.198 17:29, 1 January 2006 (UTC)
thread_title:  More on Population III Stars 

message: Do Red Dwarfs have any carbon within them? Zachorious 05:09, 31 July 2006 (UTC)
thread_title:  Carbon 

message: Why are the links to other articles in this page red? 140.198.172.119 17:52, 10 May 2007 (UTC)
replies: text: I can only see one red link in the article - maybe it was the computer you were using having odd internet settings? --Neo 18:00, 10 May 2007 (UTC)
thread_title:  link color? 

message: Hi, what happens when a red dwarf runs out of hydrogen? Are they massive enough to swich to helium fusion and become red giants, as the sun will in 5 thousand million years (sorry, still reluctant to adopt the short scale)? Yeah, I know no the universe is too young for a red dwarf to have run out of fuel anyway, but I am just curious... Steinbach (fka Caesarion) 15:21, 12 May 2007 (UTC)
thread_title:  When they leave the main sequence 

message: I thought that the White dwarf stars gradually cool to become Red dwarf stars, on their way to evolving into Black dwarf stars... is that true, or are these completely separate stars, like Brown dwarf and Sub-brown dwarf stars? (i'm asking becuase i was taught that stars go from white to red to black in grade 5, but i was always skeptical of that.  RingtailedFox • Talk • Stalk 17:18, 12 May 2007 (UTC)
replies: text: Yes and no - Yes, white dwarves will cool and emit radiation in the red region - see here, bt they're still called white dwarves, not red dwarves to avoid confusion with the stars presumably. --Neo 21:18, 12 May 2007 (UTC)
replies: text: White dwarves are partially collapsed stars comprised of degenerate matter (not neutronium however) - they are the final stage after (elderly) red giants of roughly the same mass as our sun.  A red dwarf masses much less and never collapses because its mass can be supported by interatomic forces.  Although white dwarves will eventually cool and radiate longer wavelengths, the universe isn't old enough for white dwarves to have turned red yet!  When that time comes, two stars of these types might have roughly the same size, color, and temperature, but would still be totally different.  (Apparently all kinds of strange ideas are taught in elementary and secondary science classes in America these days.  It was not always so... ) The different kinds of star are mostly determined by mass.  The larger, the brighter and shorter-lived, and the more likely to turn into a bizarre object.  The smaller, the darker and longer-lived.  Please read up on this if you are interested.Vendrov 07:53, 21 September 2007 (UTC)
thread_title:  Steller Evolution 

message: SOmeone more knowledgeable than me needs to re-add the Planets section. I just blanked it because other than the heading Planets the section was empty except for the words, "Eat anus." Basejumper2 12:54, 25 October 2007 (UTC)
replies: text: I changed the section marked "Detection" to "Planets", because the section actually discussed only detecting plants (or rather, listed recently detected planets) rather than detecting Red Dwarfs. --Noclevername (talk) 01:24, 5 March 2008 (UTC)

text: I removed the paragraph on Gl. 370 from this article. Thanks for the catch. Regards, RJH (talk) 21:30, 16 April 2012 (UTC)
thread_title:  Planets 

message: This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 10:02, 10 November 2007 (UTC)
thread_title:  WikiProject class rating

message: In the article on STARS, it is stated that low metallicity protostars with a mass of 87 x Jupiter's is the lower bound for star formation.
Here, the lower bound is 0.075 x Sun's mass which is about a factor of 7 lower. I think this seeming discrepancy needs explanation.216.96.76.236 (talk) 22:23, 20 June 2013 (UTC)
replies: text: Your "factor of 7" is the only discrepancy here. Strebe (talk) 09:32, 21 June 2013 (UTC)
thread_title:  Reconciliation between minimum mass for self-sustaining fusion and red dwarf minimum? 

message: The section "planets" ought be updated after the discovery of Kepler 186f187.59.103.179 (talk) 19:49, 19 April 2014 (UTC)
thread_title:  update 

message: Hello fellow Wikipedians,
I have just added archive links to  on Red dwarf. Please take a moment to review my edit. If necessary, add  after the link to keep me from modifying it. Alternatively, you can add  to keep me off the page altogether. I made the following changes:
*Added archive http://web.archive.org/web/20070103234953/http://www.eso.org:80/outreach/press-rel/pr-2002/pr-22-02.html to http://www.eso.org/outreach/press-rel/pr-2002/pr-22-02.html
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Cheers.—cyberbot IITalk to my owner:Online 18:19, 27 February 2016 (UTC)
thread_title:  External links modified 

message: There is a draft article called List of red dwarfs that is nearly complete. Could some editors familiar with this topic check it over and possibly get it ready for mainspace? Bradv 00:30, 11 June 2018 (UTC)
thread_title:  [[Draft:List of red dwarfs]] 

message: I am having trouble coming up with a rigorous source that is willing to commit to the least temperature a red dwarf could have. This seems to be partly because that number depends on chemical composition, and partly because it’s just really hard science, especially since late M dwarfs have a lot of dust production going on that helps obscure already faint signals. Several good papers explore the boundaries of red dwarf/brown dwarf transition as expressed by the LHS 1070 system (Köhler et al, 2012; Rajpurohit et al, 2012 for most recent), but they are unable to conclude whether LHS 1070B is a brown dwarf or a red dwarf. I infer by this that there isn’t much fusion going on in the lowest mass red dwarfs even though they are able to sustain it, and that therefore the transition is continuous between brown and red dwarf as far as measurable properties go—especially surface properties. That means the value is going to be known more from theory than from detection. Meanwhile the casual reader would probably like to have some number. I settled on ~2,500K on the basis of Köhler’s paper, but this would be for a Population I star, and I don’t find any numbers for Population II. I also perused endless lists of low mass stars, but (1) often they don’t state stellar vs brown dwarf; and (2) various sources often disagree considerably on the spectral type or surface temperature. Help? Strebe (talk) 04:51, 7 June 2019 (UTC)
replies: text: I am getting a clearer picture on why this isn't very clear. Surprisingly (to me) the most recent research thinks that the stellar cut-off is out of M entirely and near L2.0V (Dieterich et al, 2014: We find evidence for the local minimum in the radius-temperature and radius-luminosity trends that signals the end of the stellar main sequence and the start of the brown dwarf sequence at T eff ~ 2075 K, log (L/L ⊙) ~ -3.9, and (R/R ⊙) ~ 0.086. The existence of this local minimum is predicted by evolutionary models, but at temperatures ~400 K cooler[!].), with mass yet to be determined. These results are still accepted in 2019 (Winters, Henry, Jao et al. 2019) and are very different than what our little article here discusses. Will update. Strebe (talk) 18:48, 7 June 2019 (UTC)
thread_title:  Minimal temperature 

message: this reversion was some kind of slip on my part. Sorry about that. Strebe (talk) 00:46, 30 October 2021 (UTC)
thread_title:  Reversion error 

message: There is an article for every other stellar class, except class G. Class G stars seem to instead be in the Red Dwarf article, even though not all red dwarfs are class G.  — Preceding unsigned comment added by Empika1 (talk • contribs) 00:29, 11 August 2022 (UTC)
replies: text: You mean like G-type main-sequence star?  There is some inconsistency about which spectral types have a separate article and which don't, but there's also WP:GNG so possibly not everything should be in a separate article.  Is there something G-class-related that redirects here that you're concerned about?  Lithopsian (talk) 13:10, 11 August 2022 (UTC)
thread_title: Why is there no Class G Stars article?

message: If you had a mixture of potent greenhouse gases (CH2O, CO2, and CH4) and a thick atmosphere, you could have a planet further away from the star and yet habitable, right? These gases absorb a lot in the mid-IR regions (>3 microns wavelength) but are mostly transparent at near-IR and at wavelengths below 3 microns or so. The energy from the star would thus mostly pass through, while the planet's own blackbody emission would be mostly re-absorbed. 209.104.252.130 (talk) 17:19, 22 September 2022 (UTC)
replies: text: Please note that talk pages are not a discussion forum for the topic. Strebe (talk) 00:59, 23 September 2022 (UTC)
thread_title:  Habitable planets far from a red dwarf?