OGLE-2016-BLG-1928 is a rogue terrestrial planet detected through microlensing. This event was the shortest-timescale microlensing event ever detected. The lens in this event is likely a sub-Earth-mass object, which makes it one of the lowest-mass objects ever found by microlensing. The event was located in high-cadence survey fields, but only 15 data points were magnified, which made it difficult to detect.[1][2]
One of the major challenges in studying microlensing events is distinguishing genuine microlensing signals from other phenomena that can cause similar light curves. The source star in this event is located in the red giant branch, and some giants are known to produce stellar flares. However, the properties of the event do not match those of flaring stars, and there is no evidence of other flares or periodic variability in the archival data.
The properties of OGLE-2016-BLG-1928 place it at the edge of current limits of detecting short-timescale microlensing events, highlighting the challenges that will be faced by future surveys for extremely short-timescale events. This event also raises the question of whether the lack of color measurements while the source is magnified is an issue, as color measurements are critical for determining the angular Einstein radius in microlensing events exhibiting strong finite-source effects.
Despite the challenges, the discovery of OGLE-2016-BLG-1928 demonstrates that current microlensing surveys are capable of finding extremely short-timescale events. The lens in this event is one of the best candidates for a terrestrial-mass rogue planet detected to date, which is a population of low-mass free-floating (or wide-orbit) planets that may be further explored by upcoming microlensing experiments.
- ^ https://arxiv.org/pdf/2009.12377.pdf.
{{cite journal}}: Cite journal requires|journal=(help); Missing or empty|title=(help) - ^ Mroz, P.; Poleski, R.; Gould, A.; Udalski, A.; Sumi, T.; Szymanski, M. K.; Soszynski, I.; Pietrukowicz, P.; Kozlowski, S.; Skowron, J.; Ulaczyk, K.; Albrow, M. D.; Chung, S.-J.; Han, C.; Hwang, K.-H. (2020-11-01). "A terrestrial-mass rogue planet candidate detected in the shortest-timescale microlensing event". The Astrophysical Journal Letters. 903 (1): L11. doi:10.3847/2041-8213/abbfad. ISSN 2041-8205.
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