NEPTUNE’S DYNAMIC ATMOSPHERE FROMKEPLER K2OBSERVATIONS: IMPLICATIONS FOR BROWN DWARF LIGHT CURVE ANALYSES

AbstractExoplanets orbiting rapidly rotating stars may have unusual light curve shapes. These objects transit across an oblate disk with non-isotropic surface brightness, caused by the gravitational darkening. If such asymmetries are measured, one can infer the orbital obliquity of the exoplanet and the gravity darkened star, even without the analysis of the Rossiter-McLaughlin effect or interferometry. Here we introduce KOI-13 as the first example of a transiting system with a gravity darkened star.

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Light curve solutions and out-of-eclipse variability of KIC 10031409, KIC 11228612, KIC 11403216 and KIC 11913071

Serbian Astronomical Journal ◽

10.2298/saj1795033k ◽

2017 ◽

pp. 33-39 ◽

Cited By ~ 1

Author(s):

D. Kjurkchieva ◽

T. Atanasova

Keyword(s):

Light Curve ◽

Future Study ◽

Orbital Period ◽

Secondary Component ◽

Brown Dwarf ◽

Detached Binaries ◽

Rotating Star ◽

M Dwarf

We carried out light curve solutions of four detached binaries observed by Kepler. As a result, their orbital inclinations, temperatures and relative stellar radii were determined. KIC 10031409 and KIC 11228612 reveal partial eclipses while the components of KIC 11403216 and KIC 11913071 undergo total eclipses. The secondary component of KIC 11403216 is probably a very late M dwarf or brown dwarf. The out-of-eclipse brightness of KIC 10031409, KIC 11228612 and KIC 11913071 vary with the orbital period and might be explained by spots on synchronously-rotating star(s). The out-of-eclipse variability of KIC 11403216 is with a period that is a third of its orbital period and may be due to spot on asynchronous rotating component. The resonance 1:3 needs future study of KIC 11403216.

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OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensing

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1873 ◽

2019 ◽

Vol 488 (3) ◽

pp. 3308-3323 ◽

Cited By ~ 5

Author(s):

S-S Li ◽

W Zang ◽

A Udalski ◽

Y Shvartzvald ◽

D Huber ◽

...

Keyword(s):

Light Curve ◽

Gaussian Processes ◽

Angular Size ◽

Correlated Noise ◽

Brown Dwarf ◽

Minimization Method ◽

Variable Source ◽

Galactic Model ◽

Red Giant ◽

Gp Model

Abstract We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 Spitzer microlensing campaign. This is a remarkable microlensing event because its source is photometrically bright and variable, which makes it possible to perform an asteroseismic analysis using ground-based data. We find that the source star is an oscillating red giant with average time-scale of ∼9 d. The asteroseismic analysis also provides us source properties including the source angular size (∼27 $\mu$as) and distance (∼11.5 kpc), which are essential for inferring the properties of the lens. When fitting the light curve, we test the feasibility of Gaussian processes (GPs) in handling the correlated noise caused by the variable source. We find that the parameters from the GP model are generally more loosely constrained than those from the traditional χ2 minimization method. We note that this event is the first microlensing system for which asteroseismology and GPs have been used to account for the variable source. With both finite-source effect and microlens parallax measured, we find that the lens is likely a ∼0.045 M⊙ brown dwarf at distance ∼9.0 kpc, or a ∼0.073 M⊙ ultracool dwarf at distance ∼9.8 kpc. Combining the estimated lens properties with a Bayesian analysis using a Galactic model, we find a $\sim 35{{\ \rm per\ cent}}$ probability for the lens to be a bulge object and $\sim 65{{\ \rm per\ cent}}$ to be a background disc object.

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KMT-2018-BLG-0748Lb: sub-Saturn microlensing planet orbiting an ultracool host

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038173 ◽

2020 ◽

Vol 641 ◽

pp. A105 ◽

Cited By ~ 1

Author(s):

Cheongho Han ◽

In-Gu Shin ◽

Youn Kil Jung ◽

Doeon Kim ◽

Jennifer C. Yee ◽

...

Keyword(s):

High Resolution ◽

Bayesian Analysis ◽

Light Curve ◽

Planetary System ◽

Lens Model ◽

Mass Ratio ◽

Brown Dwarf ◽

Short Event ◽

Einstein Radius

Aims. We announce the discovery of a microlensing planetary system, in which a sub-Saturn planet is orbiting an ultracool dwarf host. Methods. We detected the planetary system by analyzing the short-timescale (tE ~ 4.4 days) lensing event KMT-2018-BLG-0748. The central part of the light curve exhibits asymmetry due to negative deviations in the rising side and positive deviations in the falling side. Results. We find that the deviations are explained by a binary-lens model with a mass ratio between the lens components of q ~ 2 × 10−3. The short event timescale, together with the small angular Einstein radius, θE ~ 0.11 mas, indicate that the mass of the planet host is very small. The Bayesian analysis conducted under the assumption that the planet frequency is independent of the host mass indicates that the mass of the planet is Mp = 0.18−0.10+0.29 MJ, and the mass of the host, Mh = 0.087−0.047+0.138 M⊙, is near the star–brown dwarf boundary, but the estimated host mass is sensitive to this assumption about the planet hosting probability. High-resolution follow-up observations would lead to revealing the nature of the planet host.

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The Eclipsing Binary WX Eridani

International Astronomical Union Colloquium ◽

10.1017/s0252921100073656 ◽

1979 ◽

Vol 46 ◽

pp. 385

Author(s):

M.B.K. Sarma ◽

K.D. Abhankar

Keyword(s):

Light Curve ◽

Spectral Type ◽

Orbital Period ◽

Primary Component ◽

Light Curves ◽

Absorption Feature ◽

Primary Star ◽

Eclipsing Binary ◽

The Times ◽

Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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RSCVn Stars in the Southern Hemisphere

International Astronomical Union Colloquium ◽

10.1017/s0252921100073644 ◽

1979 ◽

Vol 46 ◽

pp. 371-384 ◽

Cited By ~ 3

Author(s):

J.B. Hearnshaw

Keyword(s):

Light Curve ◽

Southern Hemisphere ◽

Orbital Period ◽

Binary Stars ◽

Small Amplitude ◽

Light Variation ◽

Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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