ABSTRACT Follow-up observations of high-magnification gravitational microlensing events can fully exploit their intrinsic sensitivity to detect extrasolar planets, especially those with small mass ratios. To make followup observations more uniform and efficient, we develop a system, HighMagFinder, to automatically alert possible ongoing high-magnification events based on the real-time data from the Korea Microlensing Telescope Network (KMTNet). We started a new phase of follow-up observations with the help of HighMagFinder in 2021. Here we report the discovery of two planets in high-magnification microlensing events, KMT-2021-BLG-0171 and KMT-2021-BLG-1689, which were identified by the HighMagFinder. We find that both events suffer the ‘central-resonant’ caustic degeneracy. The planet-host mass-ratio is q ∼ 4.7 × 10−5 or q ∼ 2.2 × 10−5 for KMT-2021-BLG-0171, and q ∼ 2.5 × 10−4 or q ∼ 1.8 × 10−4 for KMT-2021-BLG-1689. Together with two other events, four cases that suffer such degeneracy have been discovered in the 2021 season alone, indicating that the degenerate solutions may have been missed in some previous studies. We also propose a quantitative factor to weight the probability of each solution from the phase space. The resonant interpretations for the two events are disfavoured under this consideration. This factor can be included in future statistical studies to weight degenerate solutions.
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Mass Production of 2021 KMTNet Microlensing Planets. I
Abstract We inaugurate a program of “mass production” of microlensing planets discovered in 2021 KMTNet data, with the aim of laying the basis for future statistical studies. While we ultimately plan to quickly publish all 2021 planets meeting some minimal criteria, the current sample of four was chosen simply on the basis of having low initial estimates of the planet–host mass ratio, q . It is therefore notable that two members of this sample suffer from a degeneracy in the normalized source radius ρ that arises from different morphologies of closely spaced caustics. All four planets (KMT-2021-BLG-1391, KMT-2021-BLG-1253, KMT-2021-BLG-1372, KMT-2021-BLG-0748) have well-characterized mass ratios, q , and therefore are suitable for mass-ratio frequency studies. Both of the ρ degeneracies can be resolved by future adaptive optics (AO) observations on 30 m class telescopes. We provide general guidance for such AO observations for all events in anticipation of the prospect that they will revolutionize the field of microlensing planets.
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- Award ID(s):
- 2108414
- PAR ID:
- 10429479
- Date Published:
- Journal Name:
- The Astronomical Journal
- Volume:
- 164
- Issue:
- 5
- ISSN:
- 0004-6256
- Page Range / eLocation ID:
- 180
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract We continue our program of publishing all planets (and possible planets) found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data. We present four planets (KMT-2021-BLG-0712Lb, KMT-2021-BLG-0909Lb, KMT-2021-BLG-2478Lb, and KMT-2021-BLG-1105Lb), with planet-to-host mass ratios in the range − 3.3 ≲ log q ≲ − 2.2 . This brings the total of secure, by-eye, 2021 KMTNet planets to 16, including 8 in this series. The by-eye sample is an important check of the completeness of semiautomated detections, which are the basis for statistical analyses. One of the planets, KMT-2021-BLG-1105Lb, is blended with a relatively bright ( I , V ) ∼ (18.9, 21.6) star that may be the host. This could be verified immediately by high-resolution imaging. If so, the host is an early G dwarf, and the planet could be characterized by radial velocity observations on 30 m class telescopes.more » « less
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