lpetrich
Contributor
Simulations explain giant exoplanets with eccentric, close-in orbits -- ScienceDaily
That oddity is real. Of known exoplanets, their ranges of orbit eccentricities increase with increasing mass, with the champion having a projected mass of 1.5 Jupiter masses and an eccentricity of 0.95. That means that its maximum distance is 40 times its minimum distance. Some more details on that champion:
It is HD 20782 b, and it is the only known planet in its system. Its period is 1.635 (Earth) years, and its semimajor axis 1.36 AU. Its distance from its star thus ranges between 0.068 AU and 2.652 AU. The time it spends at less than twice its minimum distance is 4 days, and less than its s.m. axis distance 118 days or 0.323 years.
The star is HD 20782, and its mass is 1.07 solar masses, its radius 1.11 solar radii, its effective temperature 5790 K, and its spectral type G3V. Its metallicity index is -0.06 dex for Fe/H. Its luminosity I calculate to be 1.25 solar luminosities.
HD 20782 is almost a dead ringer for the Sun. Much like 51 Pegasi, the first "normal" star to be discovered to have an exoplanet.
The planet's equilibrium temperature thus ranges between 170 K and 1100 K.
The maximum period of that planet's moons, if any, is about 6.7 days (orbit period for the planet having a circular orbit at its closest distance). So the planet is not likely to have many moons.
The system is 36 parsecs / 117 light years away, and the star's apparent magnitude is +7.4. Its coordinates are RA = 03h20m03.58s Dec = -28d51m14.7s or RA = 50.014908, Dec = -28.854071.
Signatures of a Planet–Planet Impacts Phase in Exoplanetary Systems Hosting Giant Planets - IOPscienceAs planetary systems evolve, gravitational interactions between planets can fling some of them into eccentric elliptical orbits around the host star. Smaller planets should be more susceptible to this gravitational scattering, yet many gas giant exoplanets have been observed with eccentric orbits. In fact, the planets with the highest masses tend to be those with the most eccentric orbits. A new study explains these counter-intuitive observations.
NASA Exoplanet Archive - ICE PlotterExoplanetary systems host giant planets on substantially noncircular, close-in orbits. We propose that these eccentricities arise in a phase of giant impacts, analogous to the final stage of solar system assembly that formed Earth's Moon. In this scenario, the planets scatter each other and collide, with corresponding mass growth as they merge. We numerically integrate an ensemble of systems with varying total planet mass, allowing for collisional growth, to show that (1) the high-eccentricity giants observed today may have formed preferentially in systems of higher initial total planet mass, and (2) the upper bound on the observed giant planet eccentricity distribution is consistent with planet–planet scattering. We predict that mergers will produce a population of high-mass giant planets between 1 and 8 au from their stars.
That oddity is real. Of known exoplanets, their ranges of orbit eccentricities increase with increasing mass, with the champion having a projected mass of 1.5 Jupiter masses and an eccentricity of 0.95. That means that its maximum distance is 40 times its minimum distance. Some more details on that champion:
It is HD 20782 b, and it is the only known planet in its system. Its period is 1.635 (Earth) years, and its semimajor axis 1.36 AU. Its distance from its star thus ranges between 0.068 AU and 2.652 AU. The time it spends at less than twice its minimum distance is 4 days, and less than its s.m. axis distance 118 days or 0.323 years.
The star is HD 20782, and its mass is 1.07 solar masses, its radius 1.11 solar radii, its effective temperature 5790 K, and its spectral type G3V. Its metallicity index is -0.06 dex for Fe/H. Its luminosity I calculate to be 1.25 solar luminosities.
HD 20782 is almost a dead ringer for the Sun. Much like 51 Pegasi, the first "normal" star to be discovered to have an exoplanet.
The planet's equilibrium temperature thus ranges between 170 K and 1100 K.
The maximum period of that planet's moons, if any, is about 6.7 days (orbit period for the planet having a circular orbit at its closest distance). So the planet is not likely to have many moons.
The system is 36 parsecs / 117 light years away, and the star's apparent magnitude is +7.4. Its coordinates are RA = 03h20m03.58s Dec = -28d51m14.7s or RA = 50.014908, Dec = -28.854071.