Talk:55 Cancri f

Earth like planet?

I read this in the Daily Mail and wondered if this is new info. As i'm not really into science maybe one of you guys could field this one! See this article for me to see if i'm right, thanks! And please get back to me. From Pafcool2 20:22, 7 November 2007 (UTC)

No, this planet is not an Earth-like planet. It is a gas giant with a mass 190 times as great as the Earth. However it could possibly have a large moon, which NASA suggests might be something like the Earth; using Celestia I've made an image of this planet which can be seen here together with a hypothetical Earth-like planet. Eburacum 87.102.28.2 14:45, 8 November 2007 (UTC)

Insolation

I'm confused about something. The 55 Cancri article says that the star's luminosity is .63 solar. If the average distance is .781 AU, that should make the average insolation slightly higher than Earth (.63/.781² = 1.033), yet this article says that it receives considerably less insolation, even at perastron. Nik42 (talk) 22:00, 13 June 2008 (UTC)

To be honest, I don't even think that the insolation chart belongs in the article. It's original research (see discussion at Talk:Gliese 581 c, and it also has a bunch of extraneous information unrelated to 55 Cancri f. Deleting it now. J. Langton (talk) 13:31, 18 August 2008 (UTC)

from the text

Insolation received by 55 Cancri f

Main articles: thermodynamic equilibrium & Climate modeling

Planet Distance	Insolation (W/m2)	% of Earth's
Mars' Aphelion Flux	494.00	36.06%
Mars' Average Flux	590.589	43.11%
Mars' Perihelion Flux	718.545	52.45%
Earth's Aphelion Flux	1325.277	93.74%
Earth's Average Flux	1366.078	100.00%
55 Cancri f Apastron Flux	1396.446	102.22%
Earth's Perihelion Flux	1416.896	103.43%
55 Cancri f Average Flux	2010.882	147.20%
Venus' Aphelion Flux	2,585.411	188.72%
Venus' Average Flux	2,620.693	191.30%
Venus' Perihelion Flux	2,656.700	193.93%
55 Cancri f Periastron Flux	3142.004	230.00%

This seems incorrect - working from the stellar radius and temperature in the 55 Cancri article gives a bolometric luminosity of $\textstyle {\frac {L}{L_{\odot }}}=\left({\frac {0.96\ \mathrm {R_{\odot }} }{\mathrm {R_{\odot }} }}\right)^{2}\left({\frac {5243\ \mathrm {K} }{5780\ \mathrm {K} }}\right)^{4}=0.62$

Applying the inverse square law gives $\textstyle {\frac {f}{f_{\oplus }}}=\left({\frac {L}{L_{\odot }}}\right)\left({\frac {d}{1\ \mathrm {AU} }}\right)^{-2}$ which for apastron gives 71% and for periastron gives 160%. However note that the eccentricity of 55 Cnc f is not well constrained - it is consistent with zero (which would give a factor of 102%) and indeed in the Newtonian fit taking planet-planet interactions into account (table 4 in Fischer et al. 2008 "Five planets orbiting 55 Cancri") the eccentricity is a very low 0.0002. Icalanise (talk) 22:22, 15 September 2008 (UTC)

First, before anyone who thinks they are really smart mentions it, the Insolation article says Flux is a synonym. Second, if you are going to critisize the eccentricity used in the formula then why haven't you changed it (still 0.2) in the article itself? Thirdly, I think the formula in "FUNDAMENTALS OF ASTRONOMY" (QB43.3.B37 2006) by Dr.Cesare Barbieri, professor of Astronomy at the university of Pauda, Italy is the best planet (complete/unsimplified) Equilibium Temperature formula I have found yet.GabrielVelasquez (talk) 20:45, 20 September 2008 (UTC)

First known planet to orbit through the habitable zone?

This does not seem correct - firstly 16 Cygni Bb's orbit takes it through the habitable zone, secondly even if we select the group of extrasolar planets whose orbits lie entirely within the habitable zone, HD 28185 b got there first. I'm removing the statement from the article. Icalanise (talk) 22:06, 15 September 2008 (UTC)