Exoplanetary Science

A Planet Reborn?

June 29, 2015

Objects that seem younger than they ought to be attract attention. Take the so-called ‘blue stragglers.’ Found in open or globular clusters, they’re more luminous than the cluster stars around them, defying our expectation that stars that formed at about the same time should develop consistent with their neighbors. Allan Sandage discovered the first blue […]

Read the full article →

Kepler-138b: A Mars-Size Exoplanet

June 18, 2015

Astronomers at Penn State, NASA Ames, the University of Chicago and the SETI Institute are publishing news of an exoplanetary first: A planet smaller than Earth whose mass and size have both been measured. Kepler-138b is a Mars-sized world orbiting a red dwarf about 200 light years from Sol in the constellation Lyra. This is […]

Read the full article →

Volcanism and Astrobiology

June 10, 2015

A question in a grad school astrobiology seminar at the University of Washington prompted Amit Misra to go to work on plate tectonics. The movement of huge blocks of a planetary surface is beneficial to life because it prompts recycling, as materials move back and forth between the inside of the planet and the atmosphere. […]

Read the full article →

A Kuiper Belt in the Making

June 2, 2015

The Scorpius-Centaurus OB association is a collection of several hundred O and B-class stars some 470 light years from the Sun. Although the stars are not gravitationally bound, they are roughly the same age — 10 to 20 million years — their formation triggered by a series of supernovae explosions in large molecular clouds. Now […]

Read the full article →

Exoplanet Exploration Organization Proposed

May 26, 2015

We’ve recently looked at the role of small spacecraft, inspired in part by The Planetary Society’s LightSail, a CubeSat-based sail mission that launched last week. It’s interesting in that regard to consider small missions in the exoplanet realm. ExoplanetSat, for example, is a 3-unit CubeSat designed at MIT as a mission to discover Earth-sized exoplanets […]

Read the full article →

A Mass-Radius Relationship for ‘Sub-Neptunes’

May 22, 2015

The cascading numbers of exoplanet discoveries raise questions about how to interpret our data. In particular, what do we do about all those transit finds where we can work out a planet’s radius and need to determine its mass? Andrew LePage returns to Centauri Dreams with a look at a new attempt to derive the […]

Read the full article →

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 […]

Read the full article →

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 […]

Read the full article →

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 […]

Read the full article →

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. […]

Read the full article →