ROME/REA: A Gravitational Microlensing Search for Exoplanets Beyond the Snow Line on a Global Network of Robotic Telescopes

Tsapras, Y.; Street, R. A.; Hundertmark, M.; Bachelet, E.; Dominik, M.; Bozza, V.; Cassan, A.; Wambsganß, J.; Horne, K.; Mao, Shude; Zang, W.; Bramich, D. M.; Saha, Abhijit

doi:10.1088/1538-3873/ab3b19

Cited by 13 publications

(15 citation statements)

References 66 publications

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“…Additional observations were obtained by the ROME/REA survey (Tsapras et al 2019) using 6 × 1 m telescopes from the southern ring of the global robotic telescope network of the Las Cumbres Observatory (LCO; Brown et al 2013). The LCO telescopes are located at the Cerro Tololo International Observatory (CTIO) in Chile, South African Astronomical Observatory (SAAO) in South Africa, and Siding Spring Observatory (SSO) in Australia, and they provided good coverage of the light curve, although the event occurred early in the 2019 ROME/REA microlensing season (i.e., ∼March to September of each year, when the Galactic bulge is observable).…”

Section: Survey and Follow-up Observationsmentioning

confidence: 99%

MOA-2019-BLG-008Lb: A New Microlensing Detection of an Object at the Planet/Brown Dwarf Boundary

Bachelet

Tsapras

Gould

et al. 2022

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We report on the observations, analysis and interpretation of the microlensing event MOA-2019-BLG-008. The observed anomaly in the photometric light curve is best described through a binary lens model. In this model, the source did not cross caustics and no finite-source effects were observed. Therefore, the angular Einstein ring radius θ E cannot be measured from the light curve alone. However, the large event duration, t E ∼ 80 days, allows a precise measurement of the microlensing parallax π E. In addition to the constraints on the angular radius θ * and the apparent brightness I s of the source, we employ the Besançon and GalMod galactic models to estimate the physical properties of the lens. We find excellent agreement between the predictions of the two galactic models: the companion is likely a resident of the brown dwarf desert with a mass M p ∼ 30 M Jup, and the host is a main-sequence dwarf star. The lens lies along the line of sight to the Galactic bulge, at a distance of ≤4 kpc. We estimate that in about 10 yr the lens and source will be separated by ∼55 mas, and it will be possible to confirm the exact nature of the lensing system by using high-resolution imaging from ground- or space-based observatories.

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Section: Survey and Follow-up Observationsmentioning

confidence: 99%

MOA-2019-BLG-008Lb: A New Microlensing Detection of an Object at the Planet/Brown Dwarf Boundary

Bachelet

Tsapras

Gould

et al. 2022

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“…The degeneracy between the wide and close solutions could have been broken if the peak of the light curve had been covered from followup observations. Due to the high chance of planetary perturbations near the peaks of light curves, highmagnification events were important targets for intensive followup observations in the microlensing experiments conducted in a survey+followup mode, in which a survey experiment with a low observational cadence focused on finding events and followup teams, for example, RoboNet (Tsapras et al 2009), MiNDSTEp (Dominik et al 2010), µFUN (Gould 2006), and ROME/REA (Tsapras et al 2019), conducted intensive observations for the alerted events. In this mode of lensing experiments, it was necessary to monitor lensing events found from the survey to select target events for intensive followup observations.…”

Section: Resolving the Degeneracymentioning

confidence: 99%

KMT-2018-BLG-1743: planetary microlensing event occurring on two source stars

Han

Albrow²,

Chung³

et al. 2021

A&A

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Aims. We present the analysis of the microlensing event KMT-2018-BLG-1743. The analysis was conducted as a part of the project, in which previous lensing events detected in and before the 2019 season by the KMTNet survey were reinvestigated with the aim of finding solutions of anomalous events with no suggested plausible models. Methods. The light curve of the event, with a peak magnification Apeak ~ 800, exhibits two anomaly features, one around the peak and the other on the falling side of the light curve. An interpretation with a binary lens and a single source (2L1S) cannot describe the anomalies. By conducting additional modeling that includes an extra lens (3L1S) or an extra source (2L2S) relative to a 2L1S interpretation, we find that 2L2S interpretations with a planetary lens system and a binary source best explain the observed light curve with Δχ2 ~ 188 and ~91 over the 2L1S and 3L1S solutions, respectively. Assuming that these Δχ2 values are adequate for distinguishing the models, the event is the fourth 2L2S event and the second 2L2S planetary event. The 2L2S interpretations are subject to a degeneracy, resulting in two solutions with s > 1.0 (wide solution) and s < 1.0 (close solution). Results. The masses of the lens components and the distance to the lens are (Mhost/M⊙,Mplanet/MJ,DL/kpc)~(0.19−0.111+0.27,0.25−0.14+0.34,6.48−1.03+0.94) and ~(0.42−0.25+0.34,1.61−0.97+1.30,6.04−1.27+0.93) according to the wide and close solutions, respectively. The source is a binary composed of an early G dwarf and a mid M dwarf. The values of the relative lens-source proper motion expected from the two degenerate solutions, μwide ~ 2.3 mas yr−1 and μclose ~ 4.1 mas yr−1, are substantially different, and thus the degeneracy can be broken by resolving the lens and source from future high-resolution imaging observations.

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“…Las Cumbres Observatory (LCO; Brown et al 2013) used the 1.0m telescopes at CTIO in Chile, at SSO in Australia, and at SAAO in South Africa, as a part of LCO-Spitzer program. The ROME/REA team (Tsapras et al 2019) also used the 1.0m LCO robotic telescopes at CTIO in Chile, at SSO in Australia, and at SAAO in South Africa. A summary of observations from each telescope is given in Table 1.…”

Section: Ground-based Follow-up Observationsmentioning

confidence: 99%