• Admin
    UC Research Repository
    View Item 
       
    • UC Home
    • Library
    • UC Research Repository
    • College of Science
    • Science: Journal Articles
    • View Item
       
    • UC Home
    • Library
    • UC Research Repository
    • College of Science
    • Science: Journal Articles
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of the RepositoryCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    Statistics

    View Usage Statistics

    OGLE-2017-BLG-0173Lb: Low-mass-ratio Planet in a "Hollywood" Microlensing Event

    Thumbnail
    View/Open
    1709.08476v3.pdf (2.150Mb)
    Author
    Hwang K-H
    Udalski A
    Shvartzvald Y
    Ryu Y-H
    Albrow MD
    Chung S-J
    Gould A
    Han C
    Jung YK
    Shin I-G
    Yee JC
    Zhu W
    Cha S-M
    Kim D-J
    Kim H-W
    Kim S-L
    Lee C-U
    Lee D-J
    Lee Y
    Park B-G
    Pogge RW
    Skowron J
    Mroz P
    Poleski R
    Kozlowski S
    Soszynski I
    Pietrukowicz P
    Szymanski MK
    Ulaczyk K
    Pawlak M
    Bryden G
    Beichman C
    Novati SC
    Gaudi BS
    Henderson CB
    Jacklin S
    Penny MT
    Collaboration K
    Collaboration OGLE
    Team UKIRTM
    Date
    2018
    Permanent Link
    http://hdl.handle.net/10092/15206

    We present microlensing planet OGLE-2017-BLG-0173Lb, with planet-host mass ratio either $q\simeq 2.5\times 10^{-5}$ or $q\simeq 6.5\times 10^{-5}$, the lowest or among the lowest ever detected. The planetary perturbation is strongly detected, $\Delta\chi^2\sim 10,000$, because it arises from a bright (therefore, large) source passing over and enveloping the planetary caustic: a so-called "Hollywood" event. The factor $\sim 2.5$ offset in $q$ arises because of a previously unrecognized discrete degeneracy between Hollywood events in which the caustic is fully enveloped and those in which only one flank is enveloped, which we dub "Cannae" and "von Schlieffen", respectively. This degeneracy is "accidental" in that it arises from gaps in the data. Nevertheless, the fact that it appears in a $\Delta\chi^2=10,000$ planetary anomaly is striking. We present a simple formalism to estimate the sensitivity of other Hollywood events to planets and show that they can lead to detections close to, but perhaps not quite reaching, the Earth/Sun mass ratio of $3\times 10^{-6}$. This formalism also enables an analytic understanding of the factor $\sim 2.5$ offset in $q$ between the Cannae and von Schlieffen solutions. The Bayesian estimates for the host-mass, system distance, and planet-host projected separation are $M=0.39^{+0.40}_{-0.24}\,M_\odot$, $D_L=4.8^{+1.5}_{-1.8}\,\kpc$, and $a_\perp=3.8\pm 1.6\,\au$. The two estimates of the planet mass are $m_p=3.3^{+3.8}_{-2.1}\,M_\oplus$ and $m_p=8^{+11}_{-6}\,M_\oplus$. The measured lens-source relative proper motion $\mu=6\,\masyr$ will permit imaging of the lens in about 15 years or at first light on adaptive-optics imagers on next-generation telescopes. These will allow to measure the host mass but probably cannot resolve the planet-host mass-ratio degeneracy.

    Subjects
    gravitational lensing: micro
     
    planetary systems
     
    Field of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020110 - Stellar Astronomy and Planetary Systems
     
    Field of Research::02 - Physical Sciences::0201 - Astronomical and Space Sciences::020102 - Astronomical and Space Instrumentation
    Collections
    • Science: Journal Articles [910]

    UC Research Repository
    University Library
    University of Canterbury
    Private Bag 4800
    Christchurch 8140

    Phone
    364 2987 ext 8718

    Email
    ucresearchrepository@canterbury.ac.nz

    Follow us
    FacebookTwitterYoutube

    © University of Canterbury Library
    Send Feedback | Contact Us