Results 31 to 40 of about 590 (181)

Atmospheric mass-loss and evolution of short-period exoplanets: the examples of CoRoT-7b and Kepler-10b [PDF]

Monthly Notices of the Royal Astronomical Society, 2013
Short-period exoplanets potentially lose envelope masses during their evolution because of atmospheric escape caused by the intense XUV radiation from their host stars. We develop a combined model of atmospheric mass loss calculation and thermal evolution calculation of a planet to simulate its evolution and explore the dependences on the formation ...
Hiroyuki Kurokawa, Kaltenegger, L.
openaire   +2 more sources

Constraining Atmospheric Composition from the Outflow: Helium Observations Reveal the Fundamental Properties of Two Planets Straddling the Radius Gap

The Astronomical Journal
TOI-836 is a ∼2–3 Gyr K dwarf with an inner super Earth ( R  = 1.7 R _⊕ , P = 3.8 days) and an outer mini-Neptune ( R  = 2.6 R _⊕ , P = 8.6 days). JWST/NIRSpec 2.8–5.2 μ m transmission spectra are flat for both planets.
Michael Zhang, Jacob L. Bean, David Wilson, Girish Duvvuri, Christian Schneider, Heather A. Knutson, Fei Dai, Karen A. Collins, Cristilyn N. Watkins, Richard P. Schwarz, Khalid Barkaoui, Avi Shporer, Keith Horne, Ramotholo Sefako, Felipe Murgas, Enric Palle   +15 more
doaj   +1 more source

The Great Cosmic Silence: What Does the Fermi Paradox Tell About the Future of Humanity?

Global Policy, EarlyView.
ABSTRACT This article examines how institutional time horizons shape the long‐term survival prospects of human technological civilisation. While research on global catastrophic and existential risks has expanded, the temporal structures of political‐economic institutions remain underexamined.
Heikki Patomäki
wiley   +1 more source

Helium Depletion in Escaping Atmospheres of Sub-Neptunes: A Signature of Primary-to-secondary Transition

The Astrophysical Journal
Short-period sub-Neptunes are common in extrasolar systems. These sub-Neptunes are generally thought to have primary atmospheres of protoplanetary-disk gas origin.
Issei Kobayashi, Hiroyuki Kurokawa, Laura Schaefer, Satoshi Okuzumi   +3 more
doaj   +1 more source

A Metal-poor Atmosphere with a Hot Interior for a Young Sub-Neptune Progenitor: JWST/NIRSpec Transmission Spectrum of V1298 Tau b

The Astronomical Journal
We present the JWST/NIRSpec G395H transmission spectrum of the young (10–30 Myr) transiting planet V1298 Tau b (9.85 ± 0.35 R _⊕ , T _eq  = 670 K). Combined Hubble Space Telescope and JWST observations reveal a haze-free, H/He-dominated atmosphere with a
Saugata Barat, Jean-Michel Désert, Sagnick Mukherjee, Jayesh M. Goyal, Qiao Xue, Yui Kawashima, Allona Vazan, William Misener, Hilke E. Schlichting, Jonathan J. Fortney, Jacob L. Bean, Swaroop Avarsekar, Gregory W. Henry, Robin Baeyens, Michael R. Line, John H. Livingston, Trevor David, Erik A. Petigura, James T. Sikora, Hinna Shivkumar, Adina D. Feinstein, Antonija Oklopčić   +21 more
doaj   +1 more source

Outflowing Helium from a Mature Mini-Neptune

The Astrophysical Journal Letters, 2023
We announce the detection of escaping helium from TOI 2134b, a mini-Neptune a few gigayears old. The average in-transit absorption spectrum shows a peak of 0.37% ± 0.05% and an equivalent width of W _avg = 3.3 ± 0.3 mÅ.
Michael Zhang, Fei Dai, Jacob L. Bean, Heather A. Knutson, Federica Rescigno   +4 more
doaj   +1 more source

Effect of Laboratory Reagents for Cleaning Modern Contamination on the δ15N Integrity of Nitrogen‐Poor Samples

Rapid Communications in Mass Spectrometry, Volume 40, Issue 19, 15 October 2026.
ABSTRACT Rationale Nitrogen isotope values have been widely used for tracing ancient biogeochemical processes, but contaminant‐sensitive materials, such as Precambrian sedimentary rocks, meteorites, or returned extraterrestrial samples, often have low nitrogen levels and are thus vulnerable to modern organic contamination.
Kunmanee Bubphamanee, Andrew Schauer, Roger Buick   +2 more
wiley   +1 more source

Massive Rocky Planets May Suppress Deep Melting

AGU Advances, Volume 7, Issue 4, August 2026.
Abstract Melting properties of silicates are critical to understanding the thermal evolution of rocky planetary interiors. In the deep mantles of massive rocky planets, post‐post‐spinel Mg2SiO4 ${\text{Mg}}_{2}{\text{SiO}}_{4}$ is potentially one of the most abundant mineral phases, yet its melting behavior remains unconstrained. Here, we determine the
Donghao Zheng, Yihang Peng, Jie Deng
wiley   +1 more source

Sub-Neptune Memories. I. Implications of Inefficient Mantle Cooling and Silicate Rain

The Astrophysical Journal
We explore the evolution of sub-Neptune (radii between ∼1.5 and 4 R _⊕ ) exoplanet interior structures using our upgraded evolution code, APPLE , which self-consistently couples the thermal and compositional evolution of the whole structure.
Roberto Tejada Arevalo, Akash Gupta, Adam Burrows, Donghao Zheng, Yao Tang, Jie Deng   +5 more
doaj   +1 more source

Evolution of a Water-rich Atmosphere Formed by a Giant Impact on an Earth-sized Planet

The Astrophysical Journal, 2023
The atmosphere of a terrestrial planet that is replenished with secondary gases should have accumulated hydrogen-rich gas from its protoplanetary disk.
Kenji Kurosaki, Yasunori Hori, Masahiro Ogihara, Masanobu Kunitomo   +3 more
doaj   +1 more source