Spitzer Microlensing Parallax for OGLE-2016-BLG-1067: A Sub-Jupiter Orbiting an M Dwarf in the Disk

• Published in: The Astronomical journal Vol. 157; no. 3; pp. 121 - 135
• Main Authors: Calchi Novati, S., Suzuki, D., Udalski, A., Gould, A., Shvartzvald, Y., Bozza, V., Bennett, D. P., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., Yee, J. C., Zhu, W., Abe, F., Asakura, Y., Barry, R., Bhattacharya, A., Bond, I. A., Donachie, M., Evans, P., Fukui, A., Hirao, Y., Itow, Y., Kawasaki, K., Koshimoto, N., Li, M. C. A., Ling, C. H., Matsubara, Y., Miyazaki, S., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N. J., Saito, To, Sharan, A., Sullivan, D. J., Sumi, T., Tristram, P. J., Yamada, T., Yonehara, A., Mróz, P., Poleski, R., Skowron, J., Szyma ski, M. K., Soszy ski, I., Koz owski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Albrow, M. D., Chung, S.-J., Han, C., Hwang, K.-H., Jung, Y. K., Ryu, Y.-H., Shin, I.-G., Zang, 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, R. W.
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center The American Astronomical Society 01.03.2019; IOP Publishing
• Subjects: Anomalies; Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; Configurations; DISTRIBUTION; DWARF STARS; Extrasolar planets; Galactic bulge; Galactic disk; Gas giant planets; GRAVITATIONAL LENSES; gravitational lensing: micro; Jupiter; Likelihood ratio; MASS; Mathematical models; Microlenses; Modelling; ORBITS; Parallax; Parameters; Physical properties; planetary systems; PLANETS; Red dwarf stars; Snow; Snow line
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/1538-3881/ab0106

We report the discovery of a sub-Jupiter-mass planet orbiting beyond the snow line of an M dwarf most likely in the Galactic disk as part of the joint Spitzer and ground-based monitoring of planetary microlensing anomalies toward the Galactic bulge. Most of the microlensing parameters are strongly constrained by the light-curve modeling, and in particular there is a Spitzer-based measurement of the microlens parallax, πE. However, there are no caustic crossings, so the angular Einstein radius has only an upper limit based on the light-curve modeling alone. Additionally, the analysis leads us to identify eight degenerate configurations: the fourfold microlensing parallax degeneracy being doubled by a degeneracy in the caustic structure present at the level of the ground-based solutions. To calculate the physical parameters, and at the same time to break the parallax degeneracy, we make use of a series of arguments: the χ2 hierarchy, the Rich argument (stating that the small-parallax solution is more likely), and a prior Galactic model. The preferred configuration, favored by a likelihood ratio of at least 4000, is for a host at with mass , orbited by a Saturn-like planet with at projected separation , about 2.1 times beyond the system snow line. Therefore, it adds to the growing population of sub-Jupiter planets orbiting beyond the snow line of M dwarfs discovered by microlensing. Based on the rules of the real-time protocol for the selection of events to be followed up with Spitzer, this planet will not enter the sample for measuring the Galactic distribution of planets.