Results 101 to 110 of about 16,322 (241)

Helium in the Extended Atmosphere of the Warm Superpuff TOI-1420b

open access: yesThe Astronomical Journal
Superpuffs are planets with exceptionally low densities ( ρ ≲ 0.1 g cm ^−3 ) and core masses ( M _c ≲ 5 M _⊕ ). Many lower-mass ( M _p ≲ 10 M _⊕ ) superpuffs are expected to be unstable to catastrophic mass loss via photoevaporation and/or boil-off ...
Shreyas Vissapragada   +13 more
doaj   +1 more source

Stability of Proton Superoxide and its Superionic Transition Under High Pressure

open access: yesAdvanced Science, Volume 12, Issue 9, March 6, 2025.
The study predicts the stable proton superoxide (HO2) under extreme conditions using Density Functional Theory (DFT)‐based crystal structure prediction. HO2 exhibits metallic behavior at high pressure, transitions to an insulator under reduced pressure, and becomes superionic with high electrical conductivity under elevated temperatures.
Zifan Wang, Wenge Yang, Duck Young Kim
wiley   +1 more source

A High-resolution Non-detection of Escaping Helium in the Ultrahot Neptune LTT 9779b: Evidence for Weakened Evaporation

open access: yesThe Astrophysical Journal Letters
The recent discovery of “ultrahot” ( P < 1 day) Neptunes has come as a surprise: some of these planets have managed to retain gaseous envelopes despite being close enough to their host stars to trigger strong photoevaporation and/or Roche lobe overflow ...
Shreyas Vissapragada   +18 more
doaj   +1 more source

APPLE: An Evolution Code for Modeling Giant Planets

open access: yesThe Astrophysical Journal
We introduce APPLE , a novel planetary evolution code designed specifically for the study of giant exoplanet and Jovian planet evolution in the era of Galileo, Juno, and Cassini. With APPLE , state-of-the-art equations of state for hydrogen, helium, ice,
Ankan Sur   +4 more
doaj   +1 more source

The multiplicity of exoplanet host stars - New low-mass stellar companions of the exoplanet host stars HD125612 and HD212301

open access: yes, 2008
Aims: We present new results from our ongoing multiplicity study of exoplanet host stars, carried out with SofI/NTT. We provide the most recent list of confirmed binary and triple star systems that harbor exoplanets.
Bakos   +36 more
core   +1 more source

Towards a Theory for the Atmospheres, Structure, and Evolution of Giant Exoplanets [PDF]

open access: yesProceedings of the International Astronomical Union, 2011
AbstractIn this short review, I summarize some of the salient features of the emerging theory of exoplanets in general, and of giant exoplanets in particular. A focus is on the characterization of transiting planets at primary and secondary eclipse, but various other related topics are covered, if only briefly.
openaire   +2 more sources

Resonant and Ultra-short-period Planet Systems Are at Opposite Ends of the Exoplanet Age Distribution

open access: yesThe Astronomical Journal
Exoplanet systems are thought to evolve on secular timescales over billions of years. This evolution is impossible to directly observe on human timescales in most individual systems.
Stephen P. Schmidt   +2 more
doaj   +1 more source

Peas-in-a-pod across the Radius Valley: Rocky Systems Are Less Uniform in Mass but More Uniform in Size and Spacing

open access: yesThe Astrophysical Journal Letters
The ubiquity of “peas-in-a-pod” architectural patterns and the existence of the radius valley each presents a striking population-level trend for planets with R _p ≤ 4 R _⊕ that serves to place powerful constraints on the formation and evolution of these
Armaan V. Goyal, Songhu Wang
doaj   +1 more source

Dynamics of Two Planets near a 2:1 Resonance: Case Studies of Known and Synthetic Exosystems on a Grid of Initial Configurations

open access: yesUniverse
The distribution of period ratios for 580 known two-planet systems is apparently nonuniform, with several sharp peaks and troughs. In particular, the vicinity of the 2:1 commensurability seems to have a deficit of systems.
Valeri Makarov   +2 more
doaj   +1 more source

Interior Evolution of Magma Oceans Exoplanets

open access: yes
The magma ocean (MO) phase typically describes the early stage of rocky planets, during which the entire planet is molten due to heat generated by accretion processes. In the case of short-period exoplanets inside the runaway greenhouse limit, this phase may last Gyrs, until the inventory of major greenhouse gasses, such as H2O and H2, is exhausted ...
Mariana Sastre   +4 more
openaire   +2 more sources

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