Exoplanets & Exomoons

Magma Oceans with a Steam Atmosphere: Detectability by Future Direct Imaging

By Keith Cowing
Press Release
May 18, 2015
Filed under
Magma Oceans with a Steam Atmosphere: Detectability by Future Direct Imaging

We present the thermal evolution and emergent spectra of solidifying terrestrial planets along with the formation of steam atmospheres.

The lifetime of a magma ocean and its spectra through a steam atmosphere depends on the orbital distance of the planet from the host star. For a type-I planet, which is formed beyond a certain critical distance from the host star, the thermal emission declines on a timescale shorter than approximately 106 years. Therefore, young stars should be targets when searching for molten planets in this orbital region. In contrast, a type-II planet, which is formed inside the critical distance, will emit significant thermal radiation from near-infrared atmospheric windows during the entire lifetime of the magma ocean. The Ks and L bands will be favorable for future direct imaging because the planet-to-star contrasts of these bands are higher than approximately 10βˆ’7-10βˆ’8. Our model predicts that, in the type-II orbital region, molten planets would be present over the main sequence of the G-type host star if the initial bulk content of water exceeds approximately 1 wt%. In visible atmospheric windows, the contrasts of the thermal emission drop below 10βˆ’10 in less than 105 years, whereas those of the reflected light remain 10βˆ’10 for both types of planets. Since the contrast level is comparable to those of reflected light from Earth-sized planets in the habitable zone, the visible reflected light from molten planets also provides a promising target for direct imaging with future ground- and space-based telescopes.

Lifetime and Spectral Evolution of a Magma Ocean with a Steam Atmosphere: Its Detectability by Future Direct Imaging

Keiko Hamano, Hajime Kawahara, Yutaka Abe, Masanori Onishi, George L. Hashimoto
(Submitted on 13 May 2015)

Comments: 17 pages, 12 figures, 1 table, accepted for publication in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1505.03552 [astro-ph.EP) (or arXiv:1505.03552v1 [astro-ph.EP] for this version)
Submission history
From: Keiko Hamano
[v1] Wed, 13 May 2015 21:03:50 GMT (3486kb)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) πŸ––πŸ»