Kavli Affiliate: Subo Dong
| First 5 Authors: Zexuan Wu, Subo Dong, Tuan Yi, Zhuokai Liu, Kareem El-Badry
| Summary:
We report discovering an exoplanet from following up a microlensing event
alerted by Gaia. The event Gaia22dkv is toward a nearby disk source at ~2.5 kpc
rather than the traditional bulge microlensing fields. Our primary analysis
yields a Jovian planet with M_p = 0.50 +/- 0.05 M_J at a projected orbital
separation r_perp = 1.63 +/- 0.17 AU. The host is a turnoff star with mass 1.24
+/- 0.06 M_sun and distance of 1.35 +/- 0.09 kpc, and at r’~14, it is far
brighter than any previously discovered microlensing planet host, opening up
the opportunity of testing the microlensing model with radial velocity (RV)
observations. RV data can be used to measure the planet’s orbital period and
eccentricity, and they also enable searching for inner planets of the
microlensing cold Jupiter, as expected from the "inner-outer correlation"
inferred from Kepler and RV discoveries. Furthermore, we show that Gaia
astrometric microlensing will not only allow precise measurements of its
angular Einstein radius theta_E, but also directly measure the microlens
parallax vector and unambiguously break a geometric light-curve degeneracy,
leading to definitive characterization of the lens system.
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