An Earth-mass Planet in a 1 au Orbit around an Ultracool Dwarf

Shvartzvald, Yossi; Yee, Jennifer C.; Novati, S. Calchi; Gould, Andrew; Lee, C.-U.; Beichman, C.; Bryden, G.; Carey, Sean; Gaudi, B. Scott; Henderson, Calen B.; Zhu, Wei; Team, Spitzer; Albrow, M. D.; Cha, Sang-Mok; Chung, Sun-Ju; Han, Cheongho; Hwang, Kyu-Ha; Jung, Youn Kil; Kim, Dong-Jin; Kim, H.-W.; Kim, S.-L.; Lee, Y.; Park, B.-G.; Pogge, Richard W.; Ryu, Yoon-Hyun; Shin, In-Gu

doi:10.3847/2041-8213/aa6d09

Cited by 127 publications

(128 citation statements)

References 48 publications

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“…Second, it can probe seamlessly to the lowest-mass hosts of brown dwarfs, even into the brown-dwarf regime itself. This is a regime that is progressively less capable of forming brown dwarfs from disk material, although it may be proficient at forming Earth-mass planets (Shvartzvald et al 2017b). Third, since microlensing is most directly sensitive to the companion/host mass ratio q, it can precisely measure the distribution of this parameter, even for samples for which the individual masses are poorly known.…”

Section: Planets At the Desert's Edgementioning

confidence: 99%

“…, we employ the method of Shvartzvald et al (2017b). In brief, this approach applies the VIL colorcolor relations of Bessell & Brett (1988) to a VIL crossmatched catalog of giant stars to derive an offset (including both instrumental zero point and extinction) between the intrinsic and observed (I − L) color.…”

Section: Cmd and Spitzer-ground Color-color Relationmentioning

confidence: 99%

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OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M p =13.4±0.9 M J , places it right at the deuteriumburning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M host =0.89±0.07 M e , and the planet has a semimajor axis a∼2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.

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Section: Planets At the Desert's Edgementioning

confidence: 99%

Section: Cmd and Spitzer-ground Color-color Relationmentioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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“…However, we can securely determine the modeling parameters in this case despite the trend in the Spitzer data. Indeed, several publications used Spitzer data (which also had similar photometric systematics) to conclude that the systematics in Spitzer data are not likely to be an issue for determining modeling parameters (e.g., Poleski et al 2016;Shvartzvald et al 2017;Zhu et al 2017). …”

Section: Space-based Observationsmentioning

confidence: 99%

“…However, there exist only a few cases that have demonstrated that microlens parallaxes can be retrieved for binary lensing events with fragmentary space-based light curves without caustic-crossing features (Han et al 2017;Shvartzvald et al 2017). Indeed, Han et al (2017) used fragmentary space-based observations obtained from Spitzer to show that the microlens parallax was measured and to confirm the measurement based on the annual microlens parallax effect.…”

Section: Introductionmentioning

confidence: 99%

OGLE-2016-BLG-0168 Binary Microlensing Event: Prediction and Confirmation of the Microlens Parallax Effect from Space-based Observations

Shin¹,

Udalski²,

Yee³

et al. 2017

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The microlens parallax is a crucial observable for conclusively identifying the nature of lens systems in microlensing events containing or composed of faint (even dark) astronomical objects such as planets, neutron stars, brown dwarfs, and black holes. With the commencement of a new era of microlensing in collaboration with space-based observations, the microlens parallax can be routinely measured. In addition, space-based observations can provide opportunities to verify the microlens parallax measured from ground-only observations and to find a unique solution to the lensing light-curve analysis. Furthermore, since most space-based observations cannot cover the full light curves of lensing events, it is also necessary to verify the reliability of the information extracted from fragmentary space-based light curves. We conduct a test based on the microlensing event OGLE-2016-BLG-0168, created by a binary lens system consisting of almost equal mass M-dwarf stars, to demonstrate that it is possible to verify the microlens parallax and to resolve degeneracies using the space-based light curve even though the observations are fragmentary. Since space-based observatories will frequently produce fragmentary light curves due to their short observing windows, the methodology of this test will be useful for next-generation microlensing experiments that combine space-based and ground-based collaboration.

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“…Although the Spitzer microlensing program has been successful in terms of measuring masses of individual planetary systems Street et al 2016; Ryu et al 2017;Shvartzvald et al 2017) and constraining the Galactic distribution of planets (Calchi Novati et al 2015a;Yee et al 2015a;Zhu et al 2017b), there is a generic uncertainty in measuring p E with a single satellite, especially in cases of single-lens events. The microlensing parallax vector p E is directly related to the displacement between the two lenssource relative trajectories…”

Section: Introductionmentioning

confidence: 99%

An Isolated Microlens Observed from K2, Spitzer, and Earth

Zhu¹,

Udalski²,

Huang³

et al. 2017

ApJL

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We present the result of microlensing event MOA-2016-BLG-290, which received observations from the twowheel Kepler (K2), Spitzer, as well as ground-based observatories. A joint analysis of data from K2 and the ground leads to two degenerate solutions of the lens mass and distance. This degeneracy is effectively broken once the (partial) Spitzer light curve is included. Altogether, the lens is found to be an extremely low-mass star or brown dwarf ( -+ M 77 23 34 J ) located in the Galactic bulge (  6.8 0.4 kpc). MOA-2016-BLG-290 is the first microlensing event for which we have signals from three well-separated (∼1 au) locations. It demonstrates the power of twosatellite microlensing experiment in reducing the ambiguity of lens properties, as pointed out independently by S. Refsdal and A. Gould several decades ago.

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An Earth-mass Planet in a 1 au Orbit around an Ultracool Dwarf

Cited by 127 publications

References 48 publications

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

OGLE-2016-BLG-0168 Binary Microlensing Event: Prediction and Confirmation of the Microlens Parallax Effect from Space-based Observations

An Isolated Microlens Observed from K2, Spitzer, and Earth

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