6 research outputs found
Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf
We report the discovery of a microlensing planet
OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio . The planetary signal, which is characterized by a short "bump" on the rising side of the lensing light curve, was densely
covered by ground-based surveys. We find that the signal can be explained by a
bright source that fully envelops the planetary caustic, i.e., a "Hollywood"
geometry. Combined with the source proper motion measured from , the
satellite parallax measurement makes it possible to precisely
constrain the lens physical parameters. The preferred solution, in which the
planet perturbs the minor image due to lensing by the host, yields a
Uranus-mass planet with a mass of orbiting
a mid M-dwarf with a mass of . There is also
a second possible solution that is substantially disfavored but cannot be ruled
out, for which the planet perturbs the major image. The latter solution yields
and . By
combining the microlensing and data together with a Galactic model, we
find in either case that the lens lies on the near side of the Galactic bulge
at a distance . Future adaptive optics
observations may decisively resolve the major image/minor image degeneracy.Comment: 34 pages, 8 figures, Submitted to AAS journa
OGLE-2018-BLG-1269Lb: A Jovian Planet with a Bright I = 16 Host
We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269 with a planetâhost mass ratio q ~ 6 Ă 10â»âŽ, i.e., 0.6 times smaller than the Jupiter/Sun mass ratio. Combined with the Gaia parallax and proper motion, a strong one-dimensional constraint on the microlens parallax vector allows us to significantly reduce the uncertainties of lens physical parameters. A Bayesian analysis that ignores any information about light from the host yields that the planet is a cold giant Mâ = (0.69)_(-0.22)^(+0.44) M_J orbiting a Sun-like star Mâ = 1.13_(-0.35)^(+0.72) M_â at a distance of D_L = 2.56_(-0.62)^(+0.92) kpc. The projected planetâhost separation is a_â = 4.61_(-1.17)^(+1.70) au. Using Gaia astrometry, we show that the blended light lies ⟠12 mas from the host and therefore must be either the host star or a stellar companion to the host. An isochrone analysis favors the former possibility at >99.6%. The host is therefore a subgiant. For host metallicities in the range of 0.0 â©œ [Fe/H] â©œ +0.3, the host and planet masses are then in the range of 1.16 â©œ M_â/M_â â©œ 1.38 and 0.74 â©œ M_â/M_Jâ©œ 0.89, respectively. Low host metallicities are excluded. The brightness and proximity of the lens make the event a strong candidate for spectroscopic follow-up both to test the microlensing solution and to further characterize the system
OGLE-2018-BLG-1269Lb: A Jovian Planet With A Bright, Host
We report the discovery of a planet in the microlensing event
OGLE-2018-BLG-1269, with planet-host mass ratio , i.e.,
times smaller than the Jupiter/Sun mass ratio. Combined with the
parallax and proper motion, a strong one-dimensional constraint on the
microlens parallax vector allows us to significantly reduce the uncertainties
of lens physical parameters. A Bayesian analysis that ignores any information
about light from the host yields that the planet is a cold giant orbiting a Sun-like star at a distance of . The projected planet-host separation is
. Using {\it Gaia} astrometry, we
show that the blended light lies mas from the host and therefore
must be either the host star or a stellar companion to the host. An isochrone
analysis favors the former possibility at . The host is therefore a
subgiant. For host metallicities in the range of , the host and planet masses are then in the range of and ,
respectively. Low host metallicities are excluded. The brightness and proximity
of the lens make the event a strong candidate for spectroscopic followup both
to test the microlensing solution and to further characterize the system.Comment: 40 pages, 11 figures, and 3 table