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New hab-zone planet HD40307g distance 42 ly, estim 7 earthmass

  1. Nov 9, 2012 #1


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    technical paper
    Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307
    Mikko Tuomi, Guillem Anglada-Escude, Enrico Gerlach, Hugh R. R. Jones, Ansgar Reiners, Eugenio J. Rivera, Steven S. Vogt, R. Paul Butler
    (Submitted on 7 Nov 2012)
    The K2.5 dwarf HD 40307 has been reported to host three super-Earths. The system lacks massive planets and is therefore a potential candidate for having additional low-mass planetary companions. We re-derive Doppler measurements from public HARPS spectra of HD 40307 to confirm the significance of the reported signals using independent data analysis methods. We also investigate these measurements for additional low-amplitude signals. We used Bayesian analysis of our radial velocities to estimate the probability densities of different model parameters. We also estimated the relative probabilities of models with differing numbers of Keplerian signals and verified their significance using periodogram analyses. We investigated the relation of the detected signals with the chromospheric emission of the star. As previously reported for other objects, we found that radial velocity signals correlated with the S-index are strongly wavelength dependent. We identify two additional clear signals with periods of 34 and 51 days, both corresponding to planet candidates with minimum masses a few times that of the Earth. An additional sixth candidate is initially found at a period of 320 days. However, this signal correlates strongly with the chromospheric emission from the star and is also strongly wavelength dependent. When analysing the red half of the spectra only, the five putative planetary signals are recovered together with a very significant periodicity at about 200 days. This signal has a similar amplitude as the other new signals reported in the current work and corresponds to a planet candidate with M sin i = 7 Me (HD 40307 g). ...

    One assumes that this will require confirmation by other planet-hunter teams. We will not know anything definite for a while. But if confirmed it is a nice find.

    Mikko Tuomi has a good track record. Most of his papers have been published in Astronomy&Astrophysics. This particular paper has already been accepted by A&A. It is 23 pages long, not just a brief communication. He is collaborating this time with Paul Butler (among others). Paul Butler was Geoff Marcy's original collaborator back in the 1990s when the very first exoplanets were being found. I tend to put some credence on this discovery. It will be very nice if confirmed.
    Last edited: Nov 9, 2012
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  3. Nov 9, 2012 #2


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  4. Nov 17, 2012 #3


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    I think its stunning that there are six super-earths in one system!
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