131 research outputs found
Evidence for Hidden Nearby Companions to Hot Jupiters
The first discovered extrasolar worlds -- giant, ``hot Jupiter'' planets on
short-period orbits -- came as a surprise to solar-system-centric models of
planet formation, prompting the development of new theories for planetary
system evolution. The near-absence of observed nearby planetary companions to
hot Jupiters has been widely quoted as evidence in support of high-eccentricity
tidal migration: a framework in which hot Jupiters form further out in their
natal protoplanetary disks before being thrown inward with extremely high
eccentricities, stripping systems of any close-in planetary companions. In this
work, we present new results from a search for transit timing variations across
the full four-year Kepler dataset, demonstrating that at least of
hot Jupiters have a nearby planetary companion. This subset of hot Jupiters is
expected to have a quiescent dynamical history such that the systems could
retain their nearby companions. We also demonstrate a ubiquity of nearby
planetary companions to warm Jupiters (), indicating that warm
Jupiters typically form quiescently. We conclude by combining our results with
existing observational constraints to propose an ``eccentric migration''
framework for the formation of short-period giant planets through post-disk
dynamical sculpting in compact multi-planet systems. Our framework suggests
that hot Jupiters constitute the natural end stage for giant planets spanning a
wide range of eccentricities, with orbits that reach small enough periapses --
either from their final orbital configurations in the disk phase, or from
eccentricity excitation in the post-disk phase -- to trigger efficient tidal
circularization.Comment: 19 pages, 5 figures, Accepted for publication in the Astronomical
Journa
The Spin-Orbit Misalignment of TOI-1842b: The First Measurement of the Rossiter-McLaughlin Effect for a Warm Sub-Saturn around a Massive Star
The mechanisms responsible for generating spin-orbit misalignments in
exoplanetary systems are still not fully understood. It is unclear whether
these misalignments are related to the migration of hot Jupiters or are a
consequence of general star and planet formation processes. One promising
method to address this question is to constrain the distribution of spin-orbit
angle measurements for a broader range of planets beyond hot Jupiters. In this
work, we present the sky-projected obliquity (\lambda=-68.1_{-14.7}^{+21.2}
\,^{\circ}) for the warm sub-Saturn TOI-1842b, obtained through a measurement
of the Rossiter-McLaughlin effect using WIYN/NEID. Using the projected
obliquity, the stellar rotation period obtained from the TESS light curve, and
the projected rotation velocity from spectral analysis, we infer the 3D
spin-orbit angle () to be \psi=73.3^{+16.3}_{-12.9} \,^{\circ}. As the
first spin-orbit angle determination made for a sub-Saturn-mass planet around a
massive () star, our result presents an
opportunity to examine the orbital geometries for new regimes of planetary
systems. When combined with archival measurements, our observations of
TOI-1842b support the hypothesis that the previously established prevalence of
misaligned systems around hot, massive stars may be driven by planet-planet
dynamical interactions. In massive stellar systems, multiple gas giants are
more likely to form and can then dynamically interact with each other to excite
spin-orbit misalignments.Comment: 8 pages, 2 tables, 2 figures, accepted for publication in ApJ
SOLES VII: The Spin-Orbit Alignment of WASP-106 b, a Warm Jupiter Along the Kraft Break
Although close-orbiting, massive exoplanets -- known as hot and warm Jupiters
-- are among the most observationally accessible known planets, their formation
pathways are still not universally agreed upon. One method to constrain the
possible dynamical histories of such planets is to measure the systems'
sky-projected spin-orbit angles using the Rossiter-McLaughlin effect. By
demonstrating whether planets orbit around the stellar equator or on offset
orbits, Rossiter-McLaughlin observations offer clues as to whether the planet
had a quiescent or violent formation history. Such measurements are, however,
only a reliable window into the history of the system if the planet in question
orbits sufficiently far from its host star; otherwise, tidal interactions with
the host star can erase evidence of past dynamical upheavals. We present a
WIYN/NEID Rossiter-McLaughlin measurement of the tidally detached warm Jupiter
WASP-106 b, which orbits a star along the Kraft break
( K). We find that WASP-106 b is consistent with a
low spin-orbit angle (\lambda=6^{+17}_{-16}\,^{\circ} and \psi =
26^{+12}_{-17}\,^{\circ}), suggesting a relatively quiescent formation history
for the system. We conclude by comparing the stellar obliquities of hot and
warm Jupiter systems, with the WASP-106 system included, to gain insight into
the possible formation routes of these populations of exoplanets.Comment: 9 pages, 2 figures. Submitted to AAS journals 8/7/2
Enhanced Size Uniformity for Near-resonant Planets
Super-Earths within the same close-in, compact planetary system tend to
exhibit a striking degree of uniformity in their radius, mass, and orbital
spacing, and this 'peas-in-a-pod' phenomenon itself serves to provide one of
the strongest constrains on planet formation at large. While it has been
recently demonstrated from independent samples that such planetary uniformity
occurs for both configurations near and distant from mean motion resonance, the
question thus remains if the strength of this uniformity itself differs between
near-resonant and nonresonant configurations such that the two modes may be
astrophysically distinct in their evolution. We thus provide in this work a
novel comparative size uniformity analysis for 48 near-resonant and 251
nonresonant multi-planet systems from the California Kepler Survey catalog,
evaluating uniformity both across systems and between planetary pairs within
the same system. We find that while multiplanet configurations exhibit strong
peas-in-a-pod size uniformity regardless of their proximity to resonance,
near-resonant configurations display enhanced intra-system size uniformity as
compared to their analogous nonresonant counterparts at the level of both
entire systems and subsystem planetary pairs and chains. These results are
broadly consistent with a variety of formation paradigms for multiplanet
systems, such as convergent migration within a turbulent protoplanetary disk or
planet-planet interactions incited by postnebular dynamical instabilities.
Nevertheless, further investigation is necessary to ascertain whether the
nonresonant and near-resonant planetary configurations respectively evolve via
a singular process or mechanisms that are dynamically distinct.Comment: 15 pages, 6 figures. Accepted to ApJ July 202
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Delaying chloroplast turnover increases water-deficit stress tolerance through the enhancement of nitrogen assimilation in rice.
Abiotic stress-induced senescence in crops is a process particularly affecting the photosynthetic apparatus, decreasing photosynthetic activity and inducing chloroplast degradation. A pathway for stress-induced chloroplast degradation that involves the CHLOROPLAST VESICULATION (CV) gene was characterized in rice (Oryza sativa) plants. OsCV expression was up-regulated with the age of the plants and when plants were exposed to water-deficit conditions. The down-regulation of OsCV expression contributed to the maintenance of the chloroplast integrity under stress. OsCV-silenced plants displayed enhanced source fitness (i.e. carbon and nitrogen assimilation) and photorespiration, leading to water-deficit stress tolerance. Co-immunoprecipitation, intracellular co-localization, and bimolecular fluorescence demonstrated the in vivo interaction between OsCV and chloroplastic glutamine synthetase (OsGS2), affecting source-sink relationships of the plants under stress. Our results would indicate that the OsCV-mediated chloroplast degradation pathway is involved in the regulation of nitrogen assimilation during stress-induced plant senescence
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