An Earth-Mass Planet and a Brown Dwarf in Orbit Around a White Dwarf
Keming Zhang, Weicheng Zang, Kareem El-Badry, Jessica R. Lu, Joshua S., Bloom, Eric Agol, B. Scott Gaudi, Quinn Konopacky, Natalie LeBaron, Shude, Mao, Sean Terry

TL;DR
This paper reports the discovery of an Earth-mass planet and a brown dwarf orbiting a white dwarf, providing evidence for planetary survival through stellar evolution and insights into future planetary system dynamics.
Contribution
It presents the first evidence of an Earth-mass planet and a brown dwarf orbiting a white dwarf, based on microlensing observations and system evolutionary analysis.
Findings
Earth-mass planet at 2.1 au from the white dwarf
Brown dwarf companion at 22 au, likely evolved from an initial 1 au orbit
Supports planetary survival during stellar evolution
Abstract
Terrestrial planets born beyond 1-3 AU have been theorized to avoid being engulfed during the red-giant phases of their host stars. Nevertheless, only a few gas-giant planets have been observed around white dwarfs (WDs) -- the end product left behind by a red giant. Here we report on evidence that the lens system that produced the microlensing event KMT-2020-BLG-0414 is composed of a WD orbited by an Earth-mass planet and a brown dwarf (BD) companion, as shown by the non-detection of the lens flux using Keck Adaptive Optics (AO). From microlensing orbital motion constraints, we determine the planet to be a Earth-mass () planet at a physical separation of au from the WD during the event. By considering the system evolutionary history, we determine the BD companion to have a projected separation of 22 au from the WD, and reject an alternative model that…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astro and Planetary Science · Astronomy and Astrophysical Research
