![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
![]() |
The Teamwork Barnstar |
To all the people who made this article possible so quickly and at such a level of quality. Amazing work! U5K0'sTalkMake WikiLove not WikiWar 18:40, 17 October 2012 (UTC) |
Somebody should add the size/mass of the planet. Nergaal ( talk) 15:00, 17 October 2012 (UTC)
Both the sources cited for the temperature give an estimate of 1,200°C. Twice editors have changed this to "at least 1,200°C", which I believe is incorrect as the sources aren't giving a lower bound. I've changed this back now. If there is a more trustworthy source for the planet's estimated temperature I'd love to see it. LukeSurl t c 10:04, 18 October 2012 (UTC)
This article should not be speedy deleted as lacking sufficient context to identify its subject, because... the contents is way too important (closest exoplanet) — Preceding unsigned comment added by 69.77.164.46 ( talk) 20:24, 18 October 2012 (UTC)
This article should not be speedy deleted as lacking sufficient context to identify its subject, because... (your reason here) -- 64.131.193.65 ( talk) 20:26, 18 October 2012 (UTC)
This is an important scientific discovery!
The article mentions one temperature. But for a tidally locked planet one would expect a very high temperature on the side facing the sun, and a lower temperature on the other. Could there then be a "horizon" with a temperature similar to ours? The article on "Tidal locking" does not provide this information either. If relevant information were available in wiki a link could be added to this article. — Preceding unsigned comment added by 213.252.171.254 ( talk) 06:47, 18 October 2012 (UTC)
Most likely, heat is transmitted from the star-facing side to the 'lee' side either through currents of molten rock or through conduction. If there is any atmosphere (perhaps of material that would be solid on Earth or likely some mixture of nitrogen and carbon dioxide) it probably whips around the planet quickly. Pbrower2a ( talk) 14:53, 18 October 2012 (UTC)
Just about every molten material has some vapor pressure, and I would expect such to be true with molten silicate rocks. There would almost certainly be some atmosphere. Water vapor would not be one of those gases. Of course anyone who knows about the physical properties of molten silica and silicates at such temperatures can say far more than I can. This very hot planet would have a truly strange atmosphere. Pbrower2a ( talk) 00:04, 20 October 2012 (UTC)
The second picture labelled "The bright star Alpha Centauri" is not useful. What is this picture actually of ? Alpha Centauri is a binary star system. There should be two of them. There is only one big blurry star in this photo. Is this photo just one of the stars ? Which star is it ? Is the planet visible in this photo ? I don't see any point in having this photo here, it contributes nothing and is just confusing. Eregli bob ( talk) 16:22, 19 October 2012 (UTC)
"At such extreme temperatures water is extremely unlikely to exist in liquid form on the planet's surface" - let's just change this to impossible! HammerFilmFan ( talk) 03:25, 18 October 2012 (UTC)
It is highly unlikely that the planet's gravitation could hold water vapor. At 305K, roughly the temperature of the hottest surface of the Pacific Ocean (the highest consistent temperature on Earth -- hot deserts can have chilly nights) the Earth has gravitation strong enough to hold gases with atomic weights above about 6 (which includes water vapor) but cannot hold either helium or hydrogen. Venus and Mars are on the margin of holding water vapor due to either high temperature or low gravity, respectively. A planet with Earth-like gravitation but an absolute temperature more than three times that of the warmest ocean surfaces on Earth could not hold water vapor in any form. Water vapor would be at most a transient item in the atmosphere of Alpha Centauri Bb much as helium is a transient item in the Earth's atmosphere.
Pbrower2a (
talk)
17:32, 22 October 2012 (UTC)
This should be the radial velocity of the planet in its orbit (compare for example the value in Jupiter), not that of the central star along our line of sight resulting from this interaction. I will replace the current value by a comment for now. Like the planet's mass, we will not know this accurately until we know the orbital inclination. -- Mirokado ( talk) 11:55, 20 October 2012 (UTC)
Information about the age of the Alpha Centauri binary system is highly technical, and doesn't further any knowledge of the planet. I think it should either be removed, or made more relevant. — Preceding unsigned comment added by 64.131.193.65 ( talk) 18:40, 18 October 2012 (UTC)
The paper Circumstellar Habitable Zones of Binary Star Systems in the Solar Neighborhood is relevant here. Typesometext ( talk) 02:02, 22 October 2012 (UTC)
Using the interpolations of the Kasting (1993) formulae from [3] (attempting to take the different spectrum for different stellar temperatures into account), a stellar temperature of 5214 K and a luminosity (bolometric) of 0.500 solar luminosities:
Limit | Relative flux (Earth = 1) | Distance (AU) |
---|---|---|
Recent Venus | 1.70 | 0.542 |
Runaway greenhouse | 1.29 | 0.622 |
Water loss | 1.06 | 0.685 |
First CO2 condensation | 0.509 | 0.991 |
Maximum greenhouse | 0.333 | 1.22 |
Early Mars | 0.296 | 1.30 |
This neglects the influence of star A which should cause small oscillations in the habitable zone extent [4]. Nevertheless this is getting quite deep into WP:OR and in any case is utterly irrelevant for Alpha Centauri Bb which is clearly far too close to the star. Such discussions may be better located at the Alpha Centauri article itself. 46.126.76.193 ( talk) 21:52, 24 October 2012 (UTC)
The lead calls this "the least massive planet known to orbit a star similar to the Sun". Kepler-20 calls that star "Sun-like" and gives masses for Kepler-20e and f that are comparable to α Cen Bb. Could this apparent contradiction be resolved? -- ἀνυπόδητος ( talk) 21:05, 19 October 2012 (UTC)
The discovery paper says "Here we report the detection of the smallest minimum mass planet detected so far around a solar-type star." so is referring to the minimum mass because it was detected with the radial velocity method. Unlike the Kepler planets that were detected by the transit method. And this is true is the smallest minimum mass planet detected so far around a solar-type star. Link to paper http://www.eso.org/public/archives/releases/sciencepapers/eso1241/eso1241a.pdf Quantanew ( talk) 05:34, 20 October 2012 (UTC)
It was left out of the press release. The discovery paper refers this discovery as the smallest minimum mass planet detected so far around a solar-type star, that removes the dubiousness of the assertion. I agreed that it can be ambiguous to laypeople, but I feel we could take a key property off the article if we rephrase it like the way you propose. Quantanew ( talk)
In the article, the magnitudes of Alpha B (parent star), Alpha A, and Sol are given, but not Alpha C (Proxima). How bright would the red dwarf be from the planet (ignoring unknown atmospheric effects, of course)? CFLeon ( talk) 23:08, 1 November 2012 (UTC)
The infobox says the temperature is over 5000 K while the text cites just over 1200. What is correct?
Also it seems that mean temperature has no meaning on a tidally locked planet if it has no atmosphere (very likely). The far side can be of any temperature, from very high to very low.
At the same time the presence of the other star at 11 AU makes the far side well illuminated with a light-day period of 3.2 Earth days.-- Anixx1 ( talk) 16:24, 10 November 2012 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
![]() |
The Teamwork Barnstar |
To all the people who made this article possible so quickly and at such a level of quality. Amazing work! U5K0'sTalkMake WikiLove not WikiWar 18:40, 17 October 2012 (UTC) |
Somebody should add the size/mass of the planet. Nergaal ( talk) 15:00, 17 October 2012 (UTC)
Both the sources cited for the temperature give an estimate of 1,200°C. Twice editors have changed this to "at least 1,200°C", which I believe is incorrect as the sources aren't giving a lower bound. I've changed this back now. If there is a more trustworthy source for the planet's estimated temperature I'd love to see it. LukeSurl t c 10:04, 18 October 2012 (UTC)
This article should not be speedy deleted as lacking sufficient context to identify its subject, because... the contents is way too important (closest exoplanet) — Preceding unsigned comment added by 69.77.164.46 ( talk) 20:24, 18 October 2012 (UTC)
This article should not be speedy deleted as lacking sufficient context to identify its subject, because... (your reason here) -- 64.131.193.65 ( talk) 20:26, 18 October 2012 (UTC)
This is an important scientific discovery!
The article mentions one temperature. But for a tidally locked planet one would expect a very high temperature on the side facing the sun, and a lower temperature on the other. Could there then be a "horizon" with a temperature similar to ours? The article on "Tidal locking" does not provide this information either. If relevant information were available in wiki a link could be added to this article. — Preceding unsigned comment added by 213.252.171.254 ( talk) 06:47, 18 October 2012 (UTC)
Most likely, heat is transmitted from the star-facing side to the 'lee' side either through currents of molten rock or through conduction. If there is any atmosphere (perhaps of material that would be solid on Earth or likely some mixture of nitrogen and carbon dioxide) it probably whips around the planet quickly. Pbrower2a ( talk) 14:53, 18 October 2012 (UTC)
Just about every molten material has some vapor pressure, and I would expect such to be true with molten silicate rocks. There would almost certainly be some atmosphere. Water vapor would not be one of those gases. Of course anyone who knows about the physical properties of molten silica and silicates at such temperatures can say far more than I can. This very hot planet would have a truly strange atmosphere. Pbrower2a ( talk) 00:04, 20 October 2012 (UTC)
The second picture labelled "The bright star Alpha Centauri" is not useful. What is this picture actually of ? Alpha Centauri is a binary star system. There should be two of them. There is only one big blurry star in this photo. Is this photo just one of the stars ? Which star is it ? Is the planet visible in this photo ? I don't see any point in having this photo here, it contributes nothing and is just confusing. Eregli bob ( talk) 16:22, 19 October 2012 (UTC)
"At such extreme temperatures water is extremely unlikely to exist in liquid form on the planet's surface" - let's just change this to impossible! HammerFilmFan ( talk) 03:25, 18 October 2012 (UTC)
It is highly unlikely that the planet's gravitation could hold water vapor. At 305K, roughly the temperature of the hottest surface of the Pacific Ocean (the highest consistent temperature on Earth -- hot deserts can have chilly nights) the Earth has gravitation strong enough to hold gases with atomic weights above about 6 (which includes water vapor) but cannot hold either helium or hydrogen. Venus and Mars are on the margin of holding water vapor due to either high temperature or low gravity, respectively. A planet with Earth-like gravitation but an absolute temperature more than three times that of the warmest ocean surfaces on Earth could not hold water vapor in any form. Water vapor would be at most a transient item in the atmosphere of Alpha Centauri Bb much as helium is a transient item in the Earth's atmosphere.
Pbrower2a (
talk)
17:32, 22 October 2012 (UTC)
This should be the radial velocity of the planet in its orbit (compare for example the value in Jupiter), not that of the central star along our line of sight resulting from this interaction. I will replace the current value by a comment for now. Like the planet's mass, we will not know this accurately until we know the orbital inclination. -- Mirokado ( talk) 11:55, 20 October 2012 (UTC)
Information about the age of the Alpha Centauri binary system is highly technical, and doesn't further any knowledge of the planet. I think it should either be removed, or made more relevant. — Preceding unsigned comment added by 64.131.193.65 ( talk) 18:40, 18 October 2012 (UTC)
The paper Circumstellar Habitable Zones of Binary Star Systems in the Solar Neighborhood is relevant here. Typesometext ( talk) 02:02, 22 October 2012 (UTC)
Using the interpolations of the Kasting (1993) formulae from [3] (attempting to take the different spectrum for different stellar temperatures into account), a stellar temperature of 5214 K and a luminosity (bolometric) of 0.500 solar luminosities:
Limit | Relative flux (Earth = 1) | Distance (AU) |
---|---|---|
Recent Venus | 1.70 | 0.542 |
Runaway greenhouse | 1.29 | 0.622 |
Water loss | 1.06 | 0.685 |
First CO2 condensation | 0.509 | 0.991 |
Maximum greenhouse | 0.333 | 1.22 |
Early Mars | 0.296 | 1.30 |
This neglects the influence of star A which should cause small oscillations in the habitable zone extent [4]. Nevertheless this is getting quite deep into WP:OR and in any case is utterly irrelevant for Alpha Centauri Bb which is clearly far too close to the star. Such discussions may be better located at the Alpha Centauri article itself. 46.126.76.193 ( talk) 21:52, 24 October 2012 (UTC)
The lead calls this "the least massive planet known to orbit a star similar to the Sun". Kepler-20 calls that star "Sun-like" and gives masses for Kepler-20e and f that are comparable to α Cen Bb. Could this apparent contradiction be resolved? -- ἀνυπόδητος ( talk) 21:05, 19 October 2012 (UTC)
The discovery paper says "Here we report the detection of the smallest minimum mass planet detected so far around a solar-type star." so is referring to the minimum mass because it was detected with the radial velocity method. Unlike the Kepler planets that were detected by the transit method. And this is true is the smallest minimum mass planet detected so far around a solar-type star. Link to paper http://www.eso.org/public/archives/releases/sciencepapers/eso1241/eso1241a.pdf Quantanew ( talk) 05:34, 20 October 2012 (UTC)
It was left out of the press release. The discovery paper refers this discovery as the smallest minimum mass planet detected so far around a solar-type star, that removes the dubiousness of the assertion. I agreed that it can be ambiguous to laypeople, but I feel we could take a key property off the article if we rephrase it like the way you propose. Quantanew ( talk)
In the article, the magnitudes of Alpha B (parent star), Alpha A, and Sol are given, but not Alpha C (Proxima). How bright would the red dwarf be from the planet (ignoring unknown atmospheric effects, of course)? CFLeon ( talk) 23:08, 1 November 2012 (UTC)
The infobox says the temperature is over 5000 K while the text cites just over 1200. What is correct?
Also it seems that mean temperature has no meaning on a tidally locked planet if it has no atmosphere (very likely). The far side can be of any temperature, from very high to very low.
At the same time the presence of the other star at 11 AU makes the far side well illuminated with a light-day period of 3.2 Earth days.-- Anixx1 ( talk) 16:24, 10 November 2012 (UTC)