A Model to Map Brown Dwarf Companions to White Dwarfs in Partial Secondary Eclipse
Authors: Arthur D. Adams, Yifan Zhou, Daniel Apai, Daphne Broski-Laing, Sarah L. Casewell, Jenni R. French, L. C. Mayorga, Lael Shin, Xianyu Tan, Ben W. P. Lew, Joshua D. Lothringer, Vivien Parmentier
Abstract
Eclipse mapping is a well-established technique for constraining the spatial emission of hot Jupiter exoplanets. Brown dwarfs in ultra-short orbits around white dwarfs are an analog to hot Jupiters that can only ever be eclipsed within a limited range of latitudes. We adapt the eigenmapping method to disentangle the signals from the ever- and never-occulted regions. The result of this signal separation is a super-position of map structures, yielding sharp boundaries at the occultation region. We introduce a model that penalizes the harmonic complexity of the model map with Tikhonov regularization, whose parameters are tuned to reproduce the fit quality of the eigenmapping model. We use JWST NIRSpec/PRISM full-orbit observations of the eclipsing WD 1202-024 system as a template to construct and run injection-recovery tests on simulated light curves, isolating both latitudinal structures as well as emission from a physically-realistic general circulation model (GCM). In the latter, the narrow equatorial jet driven by the BD's rapid rotation manifests as an eclipse depth asymmetry, which our model reproduces as a latitude-dependent phase offset. Such a model, however, is only statistically preferred at approximately $3 \times$ the signal-to-noise ratio of the JWST data. When fitting to the actual JWST data of WD 1202, the full-phase eigenbasis model is statistically preferred. However, the resulting model map of WD 1202 B does not resemble the GCM predictions, with a concentrated day-side hotspot at the sub-stellar point with an angular size $\approx 15^\circ$. Interpreting this result more carefully requires follow-up work to disentangle systematics from true emission signals. This model framework provides a means to detect emission features from these rare types of eclipses, and ultimately to test predictions of models of atmospheric circulation across hot Jupiters and their BD analogs.
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Eclipse Mapping with MIRI: 2D Map of HD 189733b from 8 μm JWST MIRI LRS ObservationsMaura Lally, R. Challener, N. Lewis et al. · 2025 · Astrophysical Journal Letters · cited 4 times · Not summarized yet
Abstract
Observations and models of transiting hot Jupiter exoplanets indicate that atmospheric circulation features may cause large spatial flux contrasts across their daysides. Previous studies have mapped these spatial flux variations through inversion of secondary eclipse data. Though eclipse mapping requires high signal-to-noise data, the first successful eclipse map—made for HD 189733b using 8 μm Spitzer IRAC data—showed the promise of the method. JWST eclipse observations provide the requisite data quality to access the unique advantages of eclipse mapping. Using two JWST MIRI low-resolution spectroscopy eclipse observations centered on 8 μm to mimic the Spitzer bandpass used in previous studi…
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Abstract
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Abstract
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Abstract
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Abstract
Hot Jupiters are thought to form through multiple pathways, some of which can leave observable signatures in the architecture of their planetary systems. Massive outer companions, in particular, can provide important constraints on the dynamical histories of hot Jupiters. We aim to characterize the occurrence rate and orbital properties of additional giant companions in hot Jupiter systems, and to investigate whether these companions provide evidence for the role of dynamical interactions in shaping the hot Jupiter population. We perform a homogeneous long-term radial-velocity analysis of 147 WASP hot Jupiter systems observed with the CORALIE spectrograph between 2007 and 2025. We identify o…
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Abstract
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In short
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Abstract
(Abridged) We present an exploration of the internal rotation of GD 278, the first pulsating extremely low-mass white dwarf that shows rotational splittings within its periodogram. We assess the theoretical frequency splittings expected for different rotation profiles and compare them to the observed frequency splittings of GD 278. To this aim, we employ an asteroseismological model representative of the pulsations of this star, obtained by using the LPCODE stellar evolution code. We also derive a rotation profile that results from detailed evolutionary calculations carried out with the MESA stellar evolution code and use it to infer the expected theoretical frequency splittings. We found th…
Prior work it builds on
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Numerical Methods for Least Squares ProblemsJ. Navarro-Pedreño · 1996 · cited 3,351 times · Not summarized yet
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