Exoplanets and M Stars

Members of NAI’s Virtual Planetary Laboratory Alumni Team and their colleagues have a new paper in the current issue of Astrobiology. They present a critical discussion of M star properties that are relevant for the long- and short-term thermal, dynamical, geological, and environmental stability of conventional liquid water habitable zone (HZ) M star planets.

Source: [Link]

April 18, 2007 / Posted by: Shige Abe

Plants on Other Planets May Not be Green

Differently colored plants may live on extra-solar planets, according to two new papers in the current issue of Astrobiology authored by members of NAI’s Virtual Planetary Laboratory Alumni Team and their colleagues. They took previously simulated planetary atmospheric compositions for Earth-like planets orbiting various star types (including M stars), generated spectra, and found that photosynthetic pigments may peak in absorbance in the blue for some star types, and red-orange and near-infrared for others. Their results also suggest that, under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth...

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April 11, 2007 / Posted by: Shige Abe

Snowball Earth and the Origin of Photosynthesis

Using atmospheric chemical models of a Snowball Earth, scientists from NAI’s Alumni Virtual Planetary Laboratory Team show that, during long and severe glacial intervals, a weak hydrological cycle coupled with photochemical reactions involving water vapor would give rise to the sustained production of hydrogen peroxide. The peroxide, upon release from melting ice into the oceans and atmosphere at the end of the snowball event, could mediate global oxidation events. Their results are published in the December 12th issue of PNAS.

Source: [Link]

December 21, 2006 / Posted by: Shige Abe

Exotic Earths

Collaborators from NAI’s Teams at NASA Goddard Space Flight Center, University of Colorado, Boulder, and Penn State as well as the former Virtual Planetary Lab Team have a paper this week in Science discussing the possible formation of “Exotic Earths.” Their models have simulated terrestrial planet growth during and after inward giant planet migration. Their results cause them to speculate that more than a third of the known systems of giant planets may harbor Earth-like planets.

Source: [Link]

September 8, 2006 / Posted by: Shige Abe

Planets Around the Stars

Researchers from NAI’s University of Washington, University of Colorado, Boulder, and Virtual Planetary Laboratory Teams have developed models testing planet formation in four known systems, 55 Cancri, HD 38529, HD 37124 and HD 74156. Placing Mars to Moon-sized planet embryos between giant planets and allowing them to evolve for 100 million years, they found terrestrial planets formed readily in 55 Cancri, sometimes with substantial water and orbits in the system’s habitable zone. They found HD 38529 is likely to support an asteroid belt and Mars-sized or smaller bodies but no notable terrestrial planets. No planets formed in HD 37124...

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July 25, 2006 / Posted by: Shige Abe

Exovegetation!

NAI’s Virtual Planetary Laboratory Team have explored the possibility of detecting exovegetation on terrestrial planets orbiting M stars. They estimated the red-shift of this surface feature using leaf optical property spectra with a three photon photosynthetic scheme. The authors have produced a model wherein a pigment-derived surface signature such as exovegetation could be detected, but would be dependent upon the extent of the vegetation on the surface, cloud cover, and viewing angle. Their paper is in the current issue of The Astrophysical Journal.

Source: [Link]

July 5, 2006 / Posted by: Shige Abe

Modeling Disk-Averaged Spectra of Earth

To assess the detectability of planetary characteristics in disk-averaged spectra, the NAI Virtual Planetary Laboratory Team has developed a spatially and spectrally resolved model of the Earth. Using infrared observations of the Earth taken by existing instruments orbiting Mars, and ground-based observations of earthshine, the model has been validated, and indicates that several atmospheric species can be identified. Models such as this one will help analyze disk averaged spectra as returned from upcoming NASA and ESA extra-solar planet detection and characterization missions. They published their results in the February issue of Astrobiology.

Source: [Link]

April 7, 2006 / Posted by: Shige Abe

Theoretical Planets Around M-Dwarfs

NAI’s Virtual Planetary Laboratory Lead Team has published new findings from their Lab about the observable, biosignature gases of theoretical planets orbiting M-Dwarf stars in this month’s Astrobiology. Their outcomes are positive for designating M-Dwarfs a viable target for future observations involving the search for life.

Source: [Link]

January 12, 2006 / Posted by: Shige Abe

Preparing for TPF: Disk-Averaged Synthetic Spectra of Mars

In this month’s issue of Astrobiology, members of NAI’s Virtual Planetary Laboratory Team published a study using their model of a Mars-like planet to ascertain the detectability of a planet’s surface and atmospheric properties from disk-averaged spectra.

Source: [Link]

August 17, 2005 / Posted by: Shige Abe