Talk:HD 85512 b
|WikiProject Astronomy / Astronomical objects||(Rated Start-class, Mid-importance)|
|A fact from HD 85512 b appeared on Wikipedia's Main Page in the Did you know? column on 6 September 2011 (check views). The text of the entry was as follows: "Did you know
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)
- 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.
Radius and Gravity
- 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 184.108.40.206 (talk) 23:28, 12 September 2011 (UTC)
There seems to be some redudancy in section Habitability:
- "water may exist in liquid form in the planet"
- "water could be present in its liquid form in the planet"
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. 220.127.116.11 (talk) 03:05, 12 November 2011 (UTC)
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)