Secondary eclipses of two brown dwarfs in the K2 fields: detection by multiple dataset merging

Abstract

By using various data sources for the stellar fluxes in overlapping campaign fields and employing full time series modeling, we report the detection of the secondary eclipses of two brown dwarfs (CWW 89Ab = EPIC 219388192b and HSHJ 430b = EPIC 211946007b). The detections yielded timings in agreement with the orbital elements derived from the earlier radial velocity measurements and eclipse depths of 70+/-12 ppm (CWW 89Ab) and 852+/-123 ppm (HSHJ 430b). While the high depth in the Kepler waveband for HSHJ 430b is in agreement with the assumption that the emitted flux comes mostly from the internal heat source and the absorbed stellar irradiation, the case of CWW 89Ab suggests very high albedo, because of the lack of sufficient thermal radiation in the Kepler waveband. Assuming completely reflective dayside hemisphere, without circulation, the maximum value of the eclipse depth due to the reflection of the stellar light is 56 ppm. By making the extreme assumption that the true eclipse depth is 3 sigma less than the observed depth, the minimum geometric albedo becomes ~0.6.

Submitted to A&A; after the first (positive) referee report; 11 pages, 11 figures, easthetic reference style with ADS links; lightweighted (1.1 Mb)

References in corpus (30)

• The K2 Mission: Characterization and Early results
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• HAT-P-11b: A Super-Neptune Planet Transiting a Bright K Star in the Kepler Field
• The Statistics of Albedo and Heat Recirculation on Hot Exoplanets
• A new set of atmosphere and evolution models for cool T-Y brown dwarfs and giant exoplanets
• Reflected Spectra and Albedos of Extrasolar Giant Planets I: Clear and Cloudy Atmospheres
• A Trend Filtering Algorithm for wide field variability surveys
• EVEREST: Pixel Level Decorrelation of K2 Light curves
• Balancing the Energy Budget of Short-Period Giant Planets: Evidence for Reflective Clouds and Optical Absorbers
• An update to the EVEREST K2 pipeline: Short cadence, saturated stars, and Kepler-like photometry down to Kp = 15
• Age Determination in Upper Scorpius with Eclipsing Binaries
• New low-mass eclipsing binary systems in Praesepe discovered by K2
• Two Transiting Earth-size Planets Near Resonance Orbiting a Nearby Cool Star
• EPIC 219388192 b - an inhabitant of the brown dwarf desert in the Ruprecht 147 open cluster
• A Significant Over-Luminosity in the Transiting Brown Dwarf CWW 89Ab
• New substellar discoveries from Kepler and K2: Is there a brown dwarf desert?
• The geometric albedo of the hot Jupiter HD 189733b measured with CHEOPS
• Improved radius determinations for the transiting brown dwarf population in the era of Gaia and TESS
• NGTS-19b : A high mass transiting brown dwarf in a 17-day eccentric orbit
• The TESS Phase Curve of KELT-1b Suggests a High Dayside Albedo
• CHEOPS finds KELT-1b darker than expected in visible light: Discrepancy between the CHEOPS and TESS eclipse depths
• HIP 33609 b: An Eccentric Brown Dwarf Transiting a V=7.3 Rapidly Rotating B-Star
• The secondary transit of the hot Jupiter WASP-121b at 2 $\mu$m
• The Interferometric Binary Epsilon Cancri in Praesepe: Precise Masses and Age
• Temporal albedo variability in the phase curve of KELT-1b
• Hotter Than Expected: HST/WFC3 Phase-resolved Spectroscopy of a Rare Irradiated Brown Dwarf with Strong Internal Heat Flux
• More planetary candidates from K2 Campaign 5 by tran_k2
• Digging Deeper for RR Lyrae Stars with Low Modulation Amplitudes