Talk:Hot Jupiter

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Is libration a process? The HAT-P-1b article says circularization is caused by tidal forces.--Gbleem 20:10, 16 September 2006 (UTC)

Short-period planet[edit]

I have redirected the above (w and wo hyphen) to this page. I'm assuming that the terms are essentially synonyms. A planet in a short period must necessarily be massive to avoid being torn apart(?).

Is there is some differentiation between the two terms, the redirect can be made its own article. A quick look at google scholar shows both terms in use in research papers. Marskell 15:57, 8 October 2006 (UTC)

There seems to be nothing either unique or special about planets that have an orbital period shorter that 24 hours. This is an arbitrary boundary determined by the fact that Earth has an rotation of 24 hrs. The category ultra-short period planets should be removed. No-one has identified anything unique or interesting about the Wasp planets (18b,19b et al). This category should be removed for clarity Gmoney484 (talk) 06:34, 28 October 2013 (UTC)

Comparatives & Sentence Structure[edit]

I've got a stylistic question about this sentence:

"In comparison, a Hot Jupiter is about eight times closer to its star than Mercury is to the Sun."

Does WP have a style guide instruction for this sort of issue? I've seen these comparisons made with greater frequency both on WP and on other web sites.

The comparison is confusing because the word "times" indicates a mathematical increase in distance but "closer" indicates a mathematical decrease in distance. So it doesn't really mean anything.

This might mean that Mercury is eight times farther away from the sun than a Hot Jupiter is from its star. Or it might mean that Hot Jupiter planets are one-eighth or about 12% the distance that Mercury is.

But maybe it's something else; I have to guess about the real meaning. 21:17, 29 April 2007 (UTC)

I understood it when I first read it, but now that you point it out, the language is somewhat confusing. You can tell from the context that they mean hot Jupiters orbit at about one eighth the distance from Mercury to the sun (about 0.05 AU, versus Mercury's orbit of approximately 0.383 AU). I have changed the wording of the sentence to clarify its meaning. (Colinsweet 11:37, 3 August 2007 (UTC))


In both of the external links, the format of the capitalization is "hot Jupiter" (unless, of course, it is at the beginning of a sentence or as in the title of the article). I changed the capitalization to be consistent with this format.(Colinsweet 12:28, 1 August 2007 (UTC))

First hot jupiter[edit]

Info about first known hot jupiter (and for that matter statistic and actual records in mass, size, or distance) is nowhere in article. This is obvious thing to do! -- (talk) 10:47, 23 December 2007 (UTC)

Gas transfer with stars[edit]

From what I understand "a number" of close binary stars transfer matter between them - would the same phenomena occur with Hot Jupiter planets - or would there merely be "material aquisition" from the solar wind? Jackiespeel (talk)

for more infor on what you're refering to, look up roche lobes —Preceding unsigned comment added by (talk) 20:01, 13 November 2008 (UTC)

Hot Neptunes & Hot Jupiters[edit]

What's the difference between Hot Neptunes and Hot Jupiters. (talk) 06:03, 3 August 2009 (UTC)

I think a hot Neptune is an extrasolar planet that orbits close to its star and is closer to Neptune in terms of its mass. A Hot Jupiter, by comparison, is much bigger - close to Jupiter's size or sometimes many times bigger. A Hot Neptune is thus smaller, but can't be too small as anything that is less than 10 times the mass of Earth belongs to the Super Earth category. -- Darthdyas (talk) 18:37, 4 January 2010 (UTC)

Merge from Puffy planet[edit]

I think it would be best if the article on Puffy planets is merged into a section of this page discussing the various radius anomalies detected in transiting hot Jupiters. It is also not entirely clear that "puffy planet" is the most common term for such worlds, as "inflated hot Jupiter" brings up more Google hits, including several papers in the first page of hits, as opposed to "puffy planet" which brings up news reports. Icalanise (talk) 20:47, 7 June 2010 (UTC)

My 1st instinct is this is the best idea so far. Deletionism of some articles like Eccentric Jupiter, which are somewhat different than Hot Jupiters (HotJups are low eccentricity) may leave some gaps in our quick-explanations to the general public. But I think puffy planets (aka Fluffy,Diffuse,Inflated, "low-density and hot") would fit in quite well with Hot Jupiters. -- Kheider (talk) 21:37, 7 June 2010 (UTC)
I vote merge; puffy planets seem like a subset of Hot Jupiters that doesn't currently have enough content to merit a separate article.
--Gyrobo (talk) 21:52, 7 June 2010 (UTC)
Yes check.svg Done. -- Kheider (talk) 09:26, 8 June 2010 (UTC)

Ignored uncircularized misfits[edit]

Wouldn't it be less confusing and more accurate to say in the article that hot Jupiters: "...nearly all have low eccentricities." instead of saying that: "They all have low eccentricities" because, for some hot Jupiters, "...being circularized" hasn't happened yet? As is the case maybe for HAT-P-2b, HAT-P-34b and COROT-10b which are all hot Jupiters in still very eccentric orbits. — Preceding unsigned comment added by (talk) 21:51, 5 January 2012 (UTC)

That's true, I knew that few hot Jupiters have high eccentricities, most probably caused by a planet further out tugging at those planets, thus destabilizing their orbits. I'll change it right now! BlueEarth (talk | contribs) 22:35, 5 January 2012 (UTC)

Why is a hot Jupiter's low density a problem for radius determination by transit measurement?[edit]

Section General characteristics: "Due to high levels of insolation they are of a lower density than they would otherwise be. This has implications for radius determination". I don't think this is well explained. For instance, is it the lower opacity of the planet's upper atmosphere that is a problem when it is of lower density? What is the mechanism that makes the lower density a problem for radius determination? --Mortense (talk) 13:49, 13 April 2012 (UTC)

Ultra-short period planet redirects here.[edit]

As more data is gathered, there are now many planets discovered with an orbital period less than a day and which are not gas giants. Examples include Kepler-42c, Kepler 70b and Kepler 70c and Kepler 78b. Should we keep "Ultra-short period planet" as a redirect to this page or not or should we expand ultra-short period planet definition to include terrestrial planets? --Artman40 (talk) 19:02, 19 July 2013 (UTC)

I'd say the latter. It is not logical to have information on hot terrestrials on an article called "hot Jupiters". Hot Jupiters would have their own subsection there with a link here. --JorisvS (talk) 15:09, 26 July 2013 (UTC)
Would it be better to rename this section to "Ultra-short period Jupiters"? --Artman40 (talk) 21:09, 19 October 2013 (UTC)
What is it you're suggesting exactly? --JorisvS (talk) 07:48, 25 October 2013 (UTC)

Mercury a Hot Jupiter?[edit]

A while ago I was watching a documentary about the death of the sun, and I came up with an idea. Could Mercury be the leftover core of a Hot Jupiter? — Preceding unsigned comment added by (talk) 03:30, 9 June 2014 (UTC)

Mercury is too far from the Sun to be the corpse. Usually a planet would have to orbit within 0.05 AU depending on its age, planet's mass and density as a gas giant, and star's radiation output, but Mercury orbits nearly 0.4 AU. PlanetStar 17:19, 9 June 2014 (UTC)

Tidally locked?[edit]

How could a gas giant become tidally locked? The sentence, "This also causes the planet to synchronize its rotation and orbital periods, so it always presents the same face to its parent star — the planet becomes tidally locked to the star." seems to me to be not backed by any evidence and to defy physics; a gas giant has no solid "face" to present to its star. Abductive (reasoning) 02:54, 19 June 2014 (UTC)

Tidally locked just means that its rotation and orbital periods are the same. The question is: how do you define the rotation period of a gas giant? Astredita (talk) 11:37, 21 June 2014 (UTC)
One could imagine the face presenting to the star constantly boiling away and winds carrying to heat to the dark side of the planet, but I don't see how tidal forces could slow down a gas giant in the first place? Abductive (reasoning) 16:47, 22 June 2014 (UTC)
The phrase "tidally locked hot jupiter" gets plenty of google hits. Astredita (talk) 09:51, 23 June 2014 (UTC)


The General Characteristics section says

They exhibit high-speed winds distributing the heat from the day side to the night side, 
thus the temperature difference between the two sides is relatively low.

Do we actually know this from observation? Is this a "by definition;" that something that did not exhibit this characteristic would not qualify as a "hot Jupiter?" Or is this something assumed based on what we know about Jovian planets, fluid/gas mechanics, etc.? I didn't slap a "citation needed" tag on it because I don't have nearly enough familiarity with the subject to know if it needs one, but it might be good to flesh this out even a little bit to clarify the basis of the assertion.

*Septegram*Talk*Contributions* 16:53, 3 August 2015 (UTC) (who may not be back for months, if ever. This is a drive-by suggestion)