OGLE-2005-BLG-071Lb, the Most Massive M-Dwarf Planetary Companion?
Abstract
We combine all available information to constrain the nature of OGLE-2005-BLG-071Lb, the second planet discovered by microlensing and the first in a high-magnification event. These include photometric and astrometric measurements from Hubble Space Telescope, as well as constraints from higher order effects extracted from the ground-based light curve, such as microlens parallax, planetary orbital motion and finite-source effects. Our primary analysis leads to the conclusion that the host of Jovian planet OGLE-2005-BLG-071Lb is an M dwarf in the foreground disk with mass M= 0.46 +/- 0.04 Msun, distance D_l = 3.3 +/- 0.4 kpc, and thick-disk kinematics v_LSR ~ 103 km/s. From the best-fit model, the planet has mass M_p = 3.8 +/- 0.4 M_Jup, lies at a projected separation r_perp = 3.6 +/- 0.2 AU from its host and so has an equilibrium temperature of T ~ 55 K, i.e., similar to Neptune. A degenerate model less favored by \Delta\chi^2 = 2.1 (or 2.2, depending on the sign of the impact parameter) gives similar planetary mass M_p = 3.4 +/- 0.4 M_Jup with a smaller projected separation, r_\perp = 2.1 +/- 0.1 AU, and higher equilibrium temperature T ~ 71 K. These results from the primary analysis suggest that OGLE-2005-BLG-071Lb is likely to be the most massive planet yet discovered that is hosted by an M dwarf. However, the formation of such high-mass planetary companions in the outer regions of M-dwarf planetary systems is predicted to be unlikely within the core-accretion scenario. There are a number of caveats to this primary analysis, which assumes (based on real but limited evidence) that the unlensed light coincident with the source is actually due to the lens, that is, the planetary host. However, these caveats could mostly be resolved by a single astrometric measurement a few years after the event.
Keywords
Cite
@article{arxiv.0804.1354,
title = {OGLE-2005-BLG-071Lb, the Most Massive M-Dwarf Planetary Companion?},
author = {Subo Dong and Andrew Gould and Andrzej Udalski and Jay Anderson and G. W. Christie and B. S. Gaudi and M. Jaroszynski and M. Kubiak and M. K. Szymanski and G. Pietrzynski and I. Soszynski and O. Szewczyk and K. Ulaczyk and L. Wyrzykowski and D. L. DePoy and D. B. Fox and A. Gal-Yam and C. Han and S. Lepine and J. McCormick and E. Ofek and B. -G. Park and R. W. Pogge and F. Abe and D. P. Bennett and I. A. Bond and T. R. Britton and A. C. Gilmore and J. B. Hearnshaw and Y. Itow and K. Kamiya and P. M. Kilmartin and A. Korpela and K. Masuda and Y. Matsubara and M. Motomura and Y. Muraki and S. Nakamura and K. Ohnishi and C. Okada and N. Rattenbury and To. Saito and T. Sako and M. Sasaki and D. Sullivan and T. Sumi and P. J. Tristram and T. Yanagisawa and P. C. M. Yock and T. Yoshoika and M. D. Albrow and J. P. Beaulieu and S. Brillant and H. Calitz and A. Cassan and K. H. Cook and Ch. Coutures and S. Dieters and D. Dominis Prester and J. Donatowicz and P. Fouque and J. Greenhill and K. Hill and M. Hoffman and K. Horne and U. G. Jorgensen and S. Kane and D. Kubas and J. B. Marquette and R. Martin and P. Meintjes and J. Menzies and K. R. Pollard and K. C. Sahu and C. Vinter and J. Wambsganss and A. Williams and M. Bode and D. M. Bramich and M. Burgdorf and C. Snodgrass and I. Steele and Vanessa Doublier and Cedric Foellmi},
journal= {arXiv preprint arXiv:0804.1354},
year = {2010}
}
Comments
51 pages, 12 figures, 3 tables, Published in ApJ