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`Irony` actually does mean `metal like`... |
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Title: WASP-1b and WASP-2b: Two new transiting exoplanets detected with SuperWASP and SOPHIE
Authors: A. Collier Cameron, F. Bouchy, G. Hebrard, P. Maxted, D. Pollacco, F. Pont, I. Skillen, B. Smalley, R. A. Street, R.G. West, D.M. Wilson, S. Aigrain, D.J. Christian, W.I. Clarkson, B. Enoch, A. Evans, A. Fitzsimmons, M. Gillon, C.A. Haswell, L. Hebb, C. Hellier, S.T. Hodgkin, K. Horne, J. Irwin, S.R. Kane, F.P. Keenan, B. Loeillet, T.A. Lister, M. Mayor, C. Moutou, A.J. Norton, J. Osborne, N. Parley, D. Queloz, R. Ryans, A.H.M.J. Triaud, S. Udry, P.J. Wheatley We have detected radial-velocity variations in two objects that were identified as being likely host stars of transiting exoplanets in the 2004 SuperWASP wide-field transit survey. Using the newly-commissioned radial-velocity spectrograph SOPHIE at the Observatoire de Haute-Provence, we found that both objects exhibit reflex orbital radial-velocity variations with amplitudes characteristic of planetary-mass companions and in-phase with the photometric orbits. Line-bisector studies rule out faint blended binaries as the cause of either the radial-velocity variations or the transits. We perform preliminary spectral analyses of the host stars, which together with their radial-velocity variations and fits to the transit light curves, yield estimates of the planetary masses and radii. WASP-1b and WASP-2b have orbital periods of 2.52 and 2.15 days respectively. Given mass estimates for their F7V and K1V primaries we derive planet masses 0.80 to 0.98 and 0.81 to 0.95 times that of Jupiter respectively. WASP-1b appears to have an inflated radius of at least 1.33 R_Jup, whereas WASP-2b has a radius in the range 0.65 to 1.26 R_Jup. Read more (44kb, PDF)
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`Irony` actually does mean `metal like`... |
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The F7V is hotter than the primary of Hat-P-1. The surface temperaute for WASP-1b might be over 600,000 w m^-1!
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Lighten up! This is a stellar board! Author: duh. "The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly. |
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The title of this thread is wrong. These two planets are the first SuperWASP planets. The New Scientist article says WASP-1b is the third puffed up planet after HD 209458 b and HAT-P-1b.
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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool. -- Richard Feynman |
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The New Scientist article says the radius of the planet is 1.3 times that of Jupiter. It is too modest. The actual value given in the preprint is 1.93 (± 0.6) RJ meaning the radius is at least 1.3 RJ! Of course, the lower limit is plausible, and even smaller radius is possible, but it seems that WASP-1b is even larger than HAT-P-1b.
The SuperWASP discoveries mean that four transiting extrasolar planets have been discovered in this month alone! This shows clearly how the search method is becoming effective.
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Science is a way of trying not to fool yourself. The first principle is that you must not fool yourself, and you are the easiest person to fool. -- Richard Feynman |
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10 more from Super-WASP
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Everything I need to know I learned through Googling. |
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I suspect the media and/or researchers are exagerating the significance of density. In our solar system, Saturn has a density of one, while Earth and Mercury have densities of about 5.5 based on water as one. The other planets are scattered in between with Jupiter at about 5 times the density of Saturn. Correct me with more accurate numbers. Therory has density increasing rapidly at about Jupiter mass(due to the formation of degenerate matter such as metalic hydrogen near the center, but this does not seem to be happening with some extra solar planets. Due to gas law (double the temperature of the gas) we expect a planet with to have half the density if it is twice as hot in kalvin degrees. Some bloating occurs with temperature for rocky planets also. Neil
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I respectfully disagree; density can tell us a great deal about both the internal structure and composition of a planet, as well as about the "behavior" of planets under a wide range of conditions--e.g., I don't think anyone predicted that gas giants could get as "puffed-up" as they do under hot Jupiter conditions. Even so, why are only some very low-density? Density probably also has some bearing on the still-raging core-accretion vs core-collapse model debate.
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"Call me old-fashioned, but I think fire is magic. And it scares me a lot." --The State |