An Earth-mass planet in a time of COVID-19: KMT-2020-BLG-0414Lb
Weicheng Zang
,
Cheongho Han
,
Iona Kondo
,
Jennifer C. Yee
,
Chung-Uk Lee
,
Andrew Gould
,
Shude Mao
,
Leandro de Almeida
,
Yossi Shvartzvald
,
Xiangyu Zhang
,
Michael D. Albrow
,
Sun-Ju Chung
,
Kyu-Ha Hwang
,
Youn Kil Jung
,
Yoon-Hyun Ryu
,
In-Gu Shin
,
Sang-Mok Cha
,
Dong-Jin Kim
,
Hyoun-Woo Kim
,
Seung-Lee Kim
,
Dong-Joo Lee
,
Yongseok Lee
,
Byeong-Gon Park
,
Richard W. Pogge
,
John Drummond
,
Thiam-Guan Tan
,
José Dias Do Nascimento Júnior
,
Dan Maoz
,
Matthew T. Penny
,
Wei Zhu
,
Ian A. Bond
,
Fumio Abe
,
Richard Barry
,
David P. Bennett
,
Aparna Bhattacharya
,
Martin Donachie
,
Hirosane Fujii
,
Akihiko Fukui
,
Yuki Hirao
,
Yoshitaka Itow
,
Rintaro Kirikawa
,
Naoki Koshimoto
,
Man Cheung Alex Li
,
Yutaka Matsubara
,
Yasushi Muraki
,
Shota Miyazaki
,
Greg Olmschenk
,
Clément Ranc
,
Nicholas J. Rattenbury
,
Yuki Satoh
,
Hikaru Shoji
,
Stela Ishitani Silva
,
Takahiro Sumi
,
Daisuke Suzuki
,
Yuzuru Tanaka
,
Paul J. Tristram
,
Tsubasa Yamawaki
,
Atsunori Yonehara
,
Andreea Petric
(1)
,
Todd Burdullis
,
Pascal Fouqué
(1, 2)
Weicheng Zang
- Function : Author
Cheongho Han
- Function : Author
Iona Kondo
- Function : Author
- PersonId : 811951
- ORCID : 0000-0002-3401-1029
Jennifer C. Yee
- Function : Author
Chung-Uk Lee
- Function : Author
Andrew Gould
- Function : Author
- PersonId : 761307
- ORCID : 0000-0001-9962-9295
Shude Mao
- Function : Author
Leandro de Almeida
- Function : Author
Yossi Shvartzvald
- Function : Author
Xiangyu Zhang
- Function : Author
Michael D. Albrow
- Function : Author
Sun-Ju Chung
- Function : Author
Kyu-Ha Hwang
- Function : Author
Youn Kil Jung
- Function : Author
Yoon-Hyun Ryu
- Function : Author
In-Gu Shin
- Function : Author
Sang-Mok Cha
- Function : Author
Dong-Jin Kim
- Function : Author
Hyoun-Woo Kim
- Function : Author
Seung-Lee Kim
- Function : Author
Dong-Joo Lee
- Function : Author
Yongseok Lee
- Function : Author
Byeong-Gon Park
- Function : Author
Richard W. Pogge
- Function : Author
John Drummond
- Function : Author
Thiam-Guan Tan
- Function : Author
- PersonId : 759303
- ORCID : 0000-0001-5603-6895
José Dias Do Nascimento Júnior
- Function : Author
Dan Maoz
- Function : Author
Matthew T. Penny
- Function : Author
Wei Zhu
- Function : Author
Ian A. Bond
- Function : Author
Fumio Abe
- Function : Author
Richard Barry
- Function : Author
David P. Bennett
- Function : Author
Aparna Bhattacharya
- Function : Author
Martin Donachie
- Function : Author
Hirosane Fujii
- Function : Author
Akihiko Fukui
- Function : Author
- PersonId : 811950
- ORCID : 0000-0002-4909-5763
Yuki Hirao
- Function : Author
Yoshitaka Itow
- Function : Author
- PersonId : 783201
- ORCID : 0000-0002-8198-1968
Rintaro Kirikawa
- Function : Author
Naoki Koshimoto
- Function : Author
- PersonId : 783764
- ORCID : 0000-0003-2302-9562
Man Cheung Alex Li
- Function : Author
Yutaka Matsubara
- Function : Author
Yasushi Muraki
- Function : Author
- PersonId : 783202
- ORCID : 0000-0003-0097-5185
Shota Miyazaki
- Function : Author
- PersonId : 811952
- ORCID : 0000-0001-9818-1513
Greg Olmschenk
- Function : Author
- PersonId : 811953
- ORCID : 0000-0001-8472-2219
Clément Ranc
- Function : Author
- PersonId : 1181264
- IdHAL : cr
Nicholas J. Rattenbury
- Function : Author
Yuki Satoh
- Function : Author
Hikaru Shoji
- Function : Author
Stela Ishitani Silva
- Function : Author
Takahiro Sumi
- Function : Author
- PersonId : 794510
- ORCID : 0000-0002-4035-5012
Daisuke Suzuki
- Function : Author
- PersonId : 794511
- ORCID : 0000-0002-5843-9433
Yuzuru Tanaka
- Function : Author
Paul J. Tristram
- Function : Author
Tsubasa Yamawaki
- Function : Author
Atsunori Yonehara
- Function : Author
Todd Burdullis
- Function : Author
Pascal Fouqué
- Function : Author
- PersonId : 755617
- ORCID : 0000-0002-1436-7351
Abstract
We report the discovery of KMT-2020-BLG-0414Lb, with a planet-to-host mass ratio q2 = 0.9-1.2 × 10-5 = 3-4 ⊕ at 1σ, which is the lowest mass-ratio microlensing planet to date. Together with two other recent discoveries (4 ≲ q/q⊕ ≲ 6), it fills out the previous empty sector at the bottom of the triangular (log s, log q) diagram, where s is the planet-host separation in units of the angular Einstein radius θE. Hence, these discoveries call into question the existence, or at least the strength, of the break in the mass-ratio function that was previously suggested to account for the paucity of very low-q planets. Due to the extreme magnification of the event, Amax ~ 1450 for the underlying single-lens event, its light curve revealed a second companion with q3 ~ 0.05 and |log s3| ~ 1, i.e., a factor ~ 10 closer to or farther from the host in projection. The measurements of the microlens parallax πE and the angular Einstein radius θE allow estimates of the host, planet and second companion masses, (M1, M2, M3) ~ (0.3 M⊙, 1.0 M⊕, 17 MJ), the planet and second companion projected separations, (a⊥,2, a⊥,3) ~ (1.5, 0.15 or 15) au, and system distance DL ~ 1 kpc. The lens could account for most or all of the blended light (I ~ 19.3) and so can be studied immediately with high-resolution photometric and spectroscopic observations that can further clarify the nature of the system. The planet was found as part of a new program of high-cadence follow-up observations of high-magnification events. The detection of this planet, despite the considerable difficulties imposed by COVID-19 (two KMT sites and OGLE were shut down), illustrates the potential utility of this program.