We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K- or M-dwarf star in the inner Galactic disk or Galactic bulge. The high-cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high-magnification event approximately 24 hr prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 ± 0.02) × 10<SUP>-4</SUP> and a separation of d = 0.97537 ± 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t <SUB>E</SUB>, and angular Einstein radius, θ<SUB>E</SUB>, along with a standard Galactic model indicates a host star mass of M <SUB>L</SUB> = 0.38<SUP>+0.34</SUP> <SUB>-0.18</SUB> M <SUB>sun</SUB> and a planet mass of M <SUB>p</SUB> = 50<SUP>+44</SUP> <SUB>-24</SUB> M <SUB>⊕</SUB>, which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4<SUP>+1.2</SUP> <SUB>-0.6</SUB> AU and a distance to the planetary system of D <SUB>L</SUB> = 6.1<SUP>+1.1</SUP> <SUB>-1.2</SUB> kpc. This separation is ~2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing.
Miyake, N., Sumi, T., Dong, S., Street, R., Mancini, L., Gould, A., et al. (2011). A sub-Saturn mass planet, MOA-2009-BLG-319Lb. THE ASTROPHYSICAL JOURNAL, 728(2), 120 [10.1088/0004-637X/728/2/120].
A sub-Saturn mass planet, MOA-2009-BLG-319Lb
Mancini L.;Ricci D.;
2011-01-01
Abstract
We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K- or M-dwarf star in the inner Galactic disk or Galactic bulge. The high-cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high-magnification event approximately 24 hr prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 ± 0.02) × 10-4 and a separation of d = 0.97537 ± 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t E, and angular Einstein radius, θE, along with a standard Galactic model indicates a host star mass of M L = 0.38+0.34 -0.18 M sun and a planet mass of M p = 50+44 -24 M ⊕, which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4+1.2 -0.6 AU and a distance to the planetary system of D L = 6.1+1.1 -1.2 kpc. This separation is ~2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
