Results tagged “extrasolar”

We present a survey on binary star systems with stellar separations less than 100 astronomical units.

An analysis of the currently known exoplanets in the habitable zones (HZs) of their host stars is of interest in both the wake of the NASA Kepler mission and with prospects for expanding the known planet population through future ground- and space-based projects.

The liquid water habitable zone (HZ) describes the orbital distance at which a terrestrial planet can maintain above-freezing conditions through regulation by the carbonate-silicate cycle.

All throughout the universe, there are stars in varying phases and ages. Planetary diversity suggests that around other stars, initially frozen worlds could be the size of Earth and provide habitable conditions once the star becomes older.

Kepler Confirms 1,284 New Planets

Scientists from Princeton University and NASA have confirmed that 1,284 objects observed outside Earth's solar system by NASA's Kepler spacecraft are indeed planets.

Next-generation space telescopes will observe the atmospheres of rocky planets orbiting nearby M-dwarfs. Understanding these observations will require well-developed theory in addition to numerical simulations.

Many observed giant planets lie on eccentric orbits. Such orbits could be the result of strong scatterings with other giant planets. The same dynamical instability that produces giant planet scatterings can also alter the orbits of terrestrial planets.

Ultracool dwarfs (UCD) encompass the population of extremely low mass stars (later than M6-type) and brown dwarfs.

Astronomers using the TRAPPIST telescope at ESO's La Silla Observatory have discovered three planets orbiting an ultracool dwarf star just 40 light-years from Earth.

Circumstellar debris disks are the extrasolar analogues of the asteroid belt and the Kuiper belt. They consist of comets and leftover planetesimals that continuously collide and produce circumstellar dust that can be observed as infrared excess or in resolved imaging.

We humans might not be the only ones to ponder our place in the universe. If intelligent aliens do roam the cosmos, they too might ask a question that has gripped humans for centuries: Are we alone?

Giant Planets in the Habitable Zone

We report the discovery of three new substellar companions to solar-type stars, HD191806, HD214823, and HD221585, based on radial velocity measurements obtained at the Haute-Provence Observatory.

The young star beta Pictoris is well known for its dusty debris disk, produced through the grinding down by collisions of planetesimals, kilometre-sized bodies in orbit around the star.

Contrary to Earth, which has a small orbital eccentricity, some exoplanets discovered in the insolation habitable zone (HZ) have high orbital eccentricities (e.g., up to an eccentricity of ∼0.97 for HD~20782~b).

Characterizing the atmospheres of extrasolar planets is the new frontier in exoplanetary science. The last two decades of exoplanet discoveries have revealed that exoplanets are very common and extremely diverse in their orbital and bulk properties.

The Imprecise Search for Habitability

As planets are being discovered around other stars by the thousands, several scientific disciplines that traditionally exist in parallel are converging, including astronomy, planetary science, and biochemistry.

We use the existence of habitable planets to impose anthropic requirements on the fine structure constant, α. To this effect, we present two considerations that restrict its value to be very near the one observed.

Stellar activity and rotation frustrate the detection of exoplanets through the radial velocity technique. This effect is particularly of concern for M dwarfs, which can remain magnetically active for billions of years.

Stability of planetary orbits around GJ 832 star system, which contains inner (GJ 832c) and outer (GJ 832b) planets, is investigated numerically and the detailed phase-space analysis are performed.

The direct detection of reflected light from exoplanets is an excellent probe for the characterization of their atmospheres.

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