Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event. (arXiv:1912.00038v1 [astro-ph.IM])

Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event. (arXiv:1912.00038v1 [astro-ph.IM])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zang_W/0/1/0/all/0/1">Weicheng Zang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dong_S/0/1/0/all/0/1">Subo Dong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gould_A/0/1/0/all/0/1">Andrew Gould</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Novati_S/0/1/0/all/0/1">Sebastiano Calchi Novati</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_P/0/1/0/all/0/1">Ping Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_H/0/1/0/all/0/1">Hongjing Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_S/0/1/0/all/0/1">Shun-Sheng Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mao_S/0/1/0/all/0/1">Shude Mao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alton_K/0/1/0/all/0/1">K.B. Alton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carey_S/0/1/0/all/0/1">Sean Carey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Christie_G/0/1/0/all/0/1">G. W. Christie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Delplancke_Strobele_F/0/1/0/all/0/1">F. Delplancke-Ströbele</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feliz_D/0/1/0/all/0/1">Dax L. Feliz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Green_J/0/1/0/all/0/1">J. Green</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hu_S/0/1/0/all/0/1">Shaoming Hu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jayasinghe_T/0/1/0/all/0/1">T. Jayasinghe</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Koff_R/0/1/0/all/0/1">R. A. Koff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kurtenkov_A/0/1/0/all/0/1">A. Kurtenkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Merand_A/0/1/0/all/0/1">A. Mérand</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Minev_M/0/1/0/all/0/1">Milen Minev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mutel_R/0/1/0/all/0/1">Robert Mutel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Natusch_T/0/1/0/all/0/1">T. Natusch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roth_T/0/1/0/all/0/1">Tyler Roth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shvartzvald_Y/0/1/0/all/0/1">Yossi Shvartzvald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sun_F/0/1/0/all/0/1">Fengwu Sun</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vanmunster_T/0/1/0/all/0/1">T. Vanmunster</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_W/0/1/0/all/0/1">Wei Zhu</a>

We report the lens mass and distance measurements of the nearby microlensing
event TCP J05074264+2447555. We measure the microlens parallax vector
${pi}_{rm E}$ using Spitzer and ground-based light curves with constraints on
the direction of lens-source relative proper motion derived from Very Large
Telescope Interferometer (VLTI) GRAVITY observations. Combining this
${pi}_{rm E}$ determination with the angular Einstein radius $theta_{rm E}$
measured by VLTI GRAVITY observations, we find that the lens is a star with
mass $M_{rm L} = 0.495 pm 0.063~M_{odot}$ at a distance $D_{rm L} = 429 pm
21~{rm pc}$. We find that the blended light basically all comes from the lens.
The lens-source proper motion is $mu_{rm rel,hel} = 26.55 pm 0.36~{rm
mas,yr^{-1}}$, so with currently available adaptive-optics (AO) instruments,
the lens and source can be resolved in 2021. This is the first microlensing
event whose lens mass is unambiguously measured by interferometry + satellite
parallax observations, which opens a new window for mass measurements of
isolated objects such as stellar-mass black holes.

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