Talk:HD 85512 b

Chart

Chart states "Plot of the orbit of HD 85512 b compared to the star's habitable zone." but doesn't specify what colour indicates habitable zone. Is it the red circle? That colour normally indicates danger. If it is red then the orbit is shown virtually always outside the habitable zone. The rest of the article does nothing to clarify the position. Tiddy (talk) 04:27, 6 September 2011 (UTC)

The color code is clearly a gradation from “too hot” to “too cold”, being somewhere in the uglygreenblue zone must be good. If you want to know more click on the photo and you'll get the legend explaining everything in detail. Arturormk (talk) 07:51, 9 September 2011 (UTC)

Thanks very much for reply Arturormk. I thought Habitabilty section contradicted diagram. Diagram shows HD 85512b much closer to Gliese 370 than the "uglygreenblue" or even the yellow zone. It shows the orbit either within the "Runaway greenhouse" zone or closer to Gliese 370. Wouldn't the possible 50% water cloud cover referred have boiled off - as probably happened with Venus - or am I missing something? Tiddy (talk) 08:36, 5 November 2011 (UTC)

Features

“The estimated temperature is noted to be similar to temperatures in South France” -- Is this some kind of joke? Arturormk (talk) 07:51, 9 September 2011 (UTC)

Its a fact. That is why "HD 85512 b is one of the best candidates for habitability ever discovered". You can see the statement's source, where it explicitly states the fact. Suraj T 08:56, 9 September 2011 (UTC)

I would assume that it was originally a tongue-in-cheek comment, not the statement of a fact. Does it mean anything to compare the temperature of an entire planet (from equator to poles, from noon to midnight) to the temperature of an arbitrarily chosen region on Earth? And does such a comparison add any informational value when it refers to a mild Earth climate? “Colder than Antarctica” or “hotter than the Gobi desert” might be reasonable comparisons, but “same as Southern France”? Arturormk (talk) 22:47, 13 September 2011 (UTC)

Incredibly unlikely, it is probably far, far hotter than any place on Earth. It receives 186 percent more energy per square metre from its parent star than Earth does from the sun, almost identical to Venus's situation. On top of that, its parent star radiates energy in the infra-red to a much greater proportion than our sun does. Infra-red is at longer wavelength than visible light and so its energy is more easily absorbed, than visible light is, at the planet’s surface, regardless of whether or not the planet surface is covered by rock or water. Infra-red light is less likely than visible light to be scattered before hitting the surface of the planet, again regardless of whether the planet is blanketed under a thick and reflective atmosphere or not. So, HD 85512 b surface and lower atmosphere is realistically absorbing far more energy than even Venus’s does from our sun. HD 85512 b is also very likely tidally locked. If it were the same mass and radius as Earth, it certainly would be tidally locked, after 5.61 billion years (the age of HD 85512) in its very close orbit to its star, at 0.26 AU. But, it is over three times the mass of Earth so probably has a much larger surface area facing its parent star which makes it even more likely to be tidally locked. Sounds hardly like the South of France, more like a hell on Earth.

I'm quite surprised that HD 85512b or Gliese 370b is no more listed among the best potentially habitable exoplanets (see: http://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets ). The fact that it is just a bit near its star than the new accepted standard for "the habitable zone", that doesn't mean it is necessarily not potentially habitable or uninhabitated. It only means that, if a form of life could exist there, than it should be very different from ours on Earth. Such a planet should be tidally locked, eternally showing the same face to its star. If some water and atmosphere are present, the strong difference of temperature between the light and dark faces should cause a cycle of eternally very strong winds. Nevertheless, under some lucky conditions, life could be possible in the borderline ring where the sun is always seen at dawn/sunset. You can read all this in a interesting article where this is explained muche better than I can do here in so few words "Life on a tidally locked planet (arVix) http://arxiv.org/pdf/1405.1025 ". — Preceding unsigned comment added by Gattolibero (talk • contribs) 15:18, 3 February 2015 (UTC)

Radius and Gravity

Has an estimate for the radius and/or surface gravity of HD 85512 b been published? If so, it would be well worth noting. --JB Gnome (talk) 17:49, 12 September 2011 (UTC)

The planet was discovered by radial velocity, which only gives the mass (well technically not even that...). To estimate the radius the planet would have to transit the star as seen from Earth which is a) unlikely and b) currently undetectable for this size planet around a star like its host. With no radius and hence no rough idea of bulk density, surface gravity is out of the question. ChiZeroOne (talk) 18:19, 12 September 2011 (UTC)

I think, doing some of my own calculation, the planet has a radius of 17200-17500 km and the surface gravity is in the region of 1.25-1.35 G. — Preceding unsigned comment added by 2.27.99.67 (talk) 23:28, 12 September 2011 (UTC)

Redudancy

There seems to be some redudancy in section Habitability:

"water may exist in liquid form in the planet"

and

"water could be present in its liquid form in the planet"

--Mortense (talk) 16:45, 13 September 2011 (UTC)

Impression needed?

Copied from article by anon: "One should be cautious in accepting an "artists impression" of what the planet may or may not look like. While some persons may have difficulty in mentally imagining an extrasolar planet given words to used to describe it, one persons impression on this and other extrasolar planet Wiki pages may constitute an error of biased interpretation than what the planet actually appears like. In this example and others like it, the artist paints a picture of planet Earth. However, facts are not clear as to whether the exoplanet has clouds or liquid water. The picture then is a wishful and glamorized fraudulent misrepresentation of the facts. Any artistic impressions of an extrasolar planets appearance should be considered highly dubious at best."

I'd say he is right. The picture should be deleted unless it has gained media attraction. That might make it notable. -Koppapa (talk) 17:16, 16 October 2011 (UTC)

Agreed. Considering the huge and surprising variety of planets in our own solar system, its foolish and misleading to have an image like that. Making it Earth like may suggest to people that life exists there, or even that other civilizations exist there. Maybe they do. But we don't want anyone to think that unless there is some sort of evidence to back it up. I'm going to delete the image. 69.165.158.194 (talk) 03:05, 12 November 2011 (UTC)

!Harley peters (talk) 03:07, 12 November 2011 (UTC)I forgot to login. Above post is mine

Atmosphere

The article makes a claim about the estimated temperature "at the top of its atmosphere", however no details are apparent for the atmosphere and later it says "provided its atmosphere is similar to our own" with respect to albedo and cloud cover. Obviously nothing is known of its atmosphere, otherwise something would be stated, so the article contains way too much conjecture for my liking. How can we know it even has an atmosphere of significance ? It is much older than the Earth and there is no known magnetic field, it may well have lost almost all of its atmosphere just like Mars or Mercury, that is if it ever had one in the first place. Note that the Super-Earth article states that "Since the atmospheres and greenhouse effects of super-Earths are unknown, the surface temperatures are unknown and generally only an equilibrium temperature is given." --EvenGreenerFish (talk) 13:16, 29 November 2011 (UTC)

All the ridiculous uncited speculations should have been removed years ago. 24.79.36.94 (talk) 20:33, 7 February 2015 (UTC)

Habitability

This article contains outdated information about this planets Habitability. First GJ 581 d if existed would most likely be a super earth sized Frozen Ocean Planet, with An ESI just above 0.50 GJ581d should not be mentioned as the most habitable candidate (As well as the fact that GJ 518d does not exist). Second This Planet is not even in the Habitable zone not even in the hot end as you see for the orbit image, the habitability sub article for this article should be updated to reflect the recalculated distance of the planet or habitable zone from the parent star. I'm not a mod so I don't think I'm allowed to add that outdated information tag. Davidbuddy9 (talk) 01:11, 6 February 2015 (UTC)

I agree, cut out the cancer that is the desperate hype of a twin of earth that these astronomers need to herald. If the diagram didn't make is so obvious that the planet is too hot, I'm sure someone doing the math would figure out using just the right Albedo guess and just the right Emissivity guess would give you a perfect climate for a beach resort. Making up an Albedo is as heinous as assuming the whole surface of the planet is farmland. It's a sick circular cycle I see trending on Wikipedia, that Wikipedians wittingly or not are in collusion with here, giving the media something to hype as miraculous, and then referencing the same hype back in the article to enlarge it. There are plenty of other articles that have notes with formulas, therefore it shouldn't a problem to have a simple effective temperature formula that Wikipedian themselves can use to verify the hyped claims and show it in the article: This Formula is quite simple and is a itself a derivation of the most basic Luminosity formula. It would not be original research to simply plug in the numbers. I note here that the Radius of the star is (to me) suspicious absent, but the effective temperature and luminosity are published. I'm only posting this formula here for user reference:
${L}_{\bigodot }=\left(4\pi {{R}_{\bigodot }}^{2}\sigma {{T}_{\bigodot }}^{4}\right)$... from the same link above (circles representing the Sun's Luminosity, Temperature, Radius respectively.).

σ = 5.670374419...×10⁻⁸ W⋅m⁻²⋅K⁻⁴‍ , ...Stefan-Boltzmann constant
${{R}_{\bigodot }}=\left(\left(\left({L}_{\bigodot }/\sigma {{T}_{\bigodot }}^{4}\right)/4\pi \right)\right)^{0.5}$

From the lead source, Pepe et al, page #1:
"HD 85512 is a K5V star with 0.126 +/- 0.008 LSun, 0.69 MSun and an effective temperature, Teff ; of 4715 +/- 102."
Therefore,

${{R}_{\bigodot }}=0.850$ (±0.0637)
Again, just to show Wikipedians shouldn't be fooled: ${T}_{eq}={T}_{\bigodot }{\left(1-a\right)}^{1/4}{\sqrt {\frac {{R}_{\bigodot }}{2D}}}$
But then you're doing the same trick the astronomers are doing using the most favorable guess for an Albedo.
The more objective comparison would be the Solar Constant of the Earth with the Irradiance/Insolation of the exoplanet,
which is even easier:

${SolarConstant}=\left({R}_{\bigodot }^{2}\sigma {{T}_{\bigodot }}^{4}\right)/D^{2}$
${SolarConstant}=\left(\left({0.0850}^{2}\right)\left({5.670373}E^{-8}\right)\left({4715}^{4}\right)\right)/0.26^{2}=1683.678$ $W/m^{2}$

compared to Earth's 1366.078 is 123.25%% of Earth's Solar Constant,
with the eccentricity of 0.12 then 140.06% at Perihelion, 110.04% at Aphelion.
so in our solar system very close to being right between Earth and Venus (100% & 193%).
I would like to see this simple test done for all of these hyped so called twins of Earth, unfortunately I don't have the time.
But feel free to copy this on to every dubiously habitable expolanet talkpage for editor reference.
24.79.36.94 (talk) 19:57, 7 February 2015 (UTC)

Another well established formula
$T={\sqrt[{4}]{\frac {(1-a)S}{4\epsilon \sigma }}}$
where Wikipedians can just plug in the numbers is at the article subsection Zero Dimensional Climate Models
But again, Albedos and Emissivity are never known, astronomers are in the fashionable habit now of using the most favorable guesses. Which end up in articles like this as fact.
24.79.36.94 (talk) 01:46, 8 February 2015 (UTC)

Possibility as target for interstellar probe section

Is this really useful information? It implies that an interstellar probe is infeasible with current technology, but provides examples of intrastellar probes with eccentric orbits as examples of top speeds. It may leave the reader to wonder if a probe could be designed to travel faster, or simply be sent on a different gravity-assisted path. The specific numbers especially convey a conclusive tone about feasibility. Have there been any papers studying specifically the idea of launching a probe to this planet? 2600:1700:31D0:2660:94DD:56C7:EDBD:548C (talk) 07:11, 28 October 2017 (UTC)

Redirect to HD 85512

The existence of HD 85512 b is currently dubious, with the recent 2023 paper finding it to be stellar activity rather than a planet. Its notability is also questionable. As such, I'm wondering if we can simply redirect to that page, as much of the text appears to be redundant for the star page. AstroChara (talk) 00:02, 12 August 2024 (UTC)

There is already a merge discussion at HD 85512. 21 Andromedae (talk) 19:18, 13 August 2024 (UTC)