Exoplanetary Science

Exoplanets: The Hunt for Circular Orbits

May 19, 2015

If you’re looking for planets that may be habitable, eccentric orbits are a problem. Vary the orbit enough and the surface goes through extreme swings in temperature. In our own Solar System, planets tend to follow circular orbits. In fact, Mercury is the planet with the highest degree of eccentricity, while the other seven planets […]

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Doppler Worlds and M-Dwarf Planets

May 15, 2015

Finding small and possibly habitable worlds around M-dwarfs has already proven controversial, as we’ve seen in recent work on Gliese 581. The existence of Gl 581d, for example, is contested in some circles, but as Guillem Anglada-Escudé argues below, sound methodology turns up a robust signal for the world. Read on to learn why as […]

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Changing Conditions on 55 Cancri e

May 5, 2015

Roughly twice the radius and eight times as massive as Earth, 55 Cancri e is a ‘super-Earth’ in the interesting five-planet system some 41 light years away in the constellation Cancer. No habitable conditions here, at least not for anything remotely like the kind of life we understand: 55 Cancri e orbits its G-class primary […]

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HD 7924: Planets with a Robotic Assist

April 29, 2015

We’ve found a lot of planets far away from the Sun but know comparatively little about what may be circling nearby stars. The rationale is clear: The Kepler mission’s field of view was carefully chosen to provide a large sample (over 145,000 main sequence stars) that could be studied for transits by the spacecraft’s photometer. […]

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Exoplanet Spectrum in Visible Light

April 27, 2015

It’s the twentieth anniversary of the discovery of 51 Pegasi b, a ‘hot Jupiter’ that was the first planet to be discovered around a normal star. I always have to throw in that ‘normal’ qualifier because it was in 1992 that Aleksander Wolszczan and Dale Frail announced their discovery of planets around the pulsar PSR […]

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Habitable Worlds Around Tau Ceti?

April 24, 2015

Yesterday’s look at NExSS (the Nexus for Exoplanet System Science), NASA’s new ‘virtual institute,’ focused on the multidisciplinary nature of the effort. The work I’m looking at today, an analysis of the planets around Tau Ceti performed at Arizona State University, only emphasizes the same point. To get a read on whether two planets that […]

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Exomoons: A Data Search for the Orbital Sampling Effect and the Scatter Peak

April 17, 2015

Exomoons continue to be elude us, though they’re under intense study. One detection strategy is called Orbital Sampling Effect, as explained in the article below. I’ll let Michael Hippke describe it, but the intriguing fact is that we can work with these methods using existing datasets to refine our techniques and actively hunt for candidates. […]

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Near-Term Missions: What the Future Holds

April 10, 2015

Discussing the state of space mission planning recently with Centauri Dreams contributor Ashley Baldwin, I mentioned my concerns about follow-up missions to the outer planets once New Horizons has done its job at Pluto/Charon. No one is as plugged into mission concepts as Dr. Baldwin, and as he discussed what’s coming up both in exoplanet […]

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Habitable Worlds on Circumbinary Orbits?

April 2, 2015

Before I get into some NASA-funded exoplanet work that grew out of a study of the binary nature of Pluto and Charon, I want to mention that NASA TV will air an event of exoplanet interest on Tuesday the 7th, from 1700 to 1800 UTC. A panel of experts will be discussing the search for […]

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An Alpha Centauri Bb Transit Search

March 30, 2015

Alpha Centauri continues to be a maddening and elusive subject for study. Two decades of radial velocity work on Centauri A and B have been able to constrain the possibilities — we’ve learned that there are no gas giants larger than Jupiter in orbits within 2 AU of either of the stars. But lower mass […]

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