OGLE-2005-BLG-071Lb, the Most Massive M-Dwarf Planetary Companion?

Authors: Subo Dong, Andrew Gould, Andrzej Udalski, Jay Anderson, G.W. Christie, B.S. Gaudi, M. Jaroszynski, M. Kubiak, M.K. Szymanski, G. Pietrzynski, I. Soszynski, O. Szewczyk, K. Ulaczyk, L. Wyrzykowski, D.L. DePoy, D.B. Fox, A. Gal-Yam, C. Han, S. Lepine, J. McCormick, E. Ofek, B.-G. Park, R.W. Pogge, F. Abe, D.P. Bennett, I.A. Bond, T.R. Britton, A.C. Gilmore, J.B. Hearnshaw, Y. Itow, K. Kamiya, P.M. Kilmartin, A. Korpela, K. Masuda, Y. Matsubara, M. Motomura, Y. Muraki, S. Nakamura, K. Ohnishi, C. Okada, N. Rattenbury, To. Saito, T. Sako, M. Sasaki, D. Sullivan, T. Sumi, P.J. Tristram, T. Yanagisawa, P.C.M. Yock, T. Yoshoika, M.D. Albrow, J.P. Beaulieu, S. Brillant, H. Calitz, A. Cassan, K. H. Cook, Ch. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouque, J. Greenhill, K. Hill, et al (20 additional authors not shown)

(Submitted on 9 Apr 2008)

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 a foreground M dwarf, with mass M = 0.46 +/- 0.04 Msun, distance D_lens = 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 = 3.5 +/- 0.3 M_Jup, lies at a projected separation r_perp = 3.6 +/- 0.2 AU from its host and has an equilibrium temperature of T ~ 50 K, i.e., similar to Neptune. A degenerate model less favored by \Delta\chi^2 ~ 4 gives essentially the same planetary mass M_p = 3.3 +/- 0.4 M_Jup with a smaller projected separation, r_perp = 2.1 +/- 0.1 AU, and higher equilibrium temperature T ~ 70 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 analysis, but these could mostly be resolved by a single astrometric measurement a few years after the event.

Comments: 50 pages, 13 figures, 3 tables, Submitted to ApJ

Subjects: Astrophysics (astro-ph)

Cite as: arXiv:0804.1354v1 [astro-ph]

Submission history

From: Subo Dong [view email]

[v1] Wed, 9 Apr 2008 19:29:02 GMT (948kb)

http://arxiv.org/abs/0804.1354