lpetrich
Contributor
[1906.03266] Signatures of a planet-planet impacts phase in exoplanetary systems hosting giant planets
The authors used stars' "metallicity" as a proxy for the amount of heavy elements in the stars' protoplanetary disks. "Heavy" being heavier than hydrogen and helium. Astrophysicists call all such heavy elements "metals". This is important because Jovian planets likely form from large icy or rocky planets, by collecting hydrogen and helium from the protoplanetary nebula.
Furthermore, one would expect planets to have circular and coplanar orbits. That is approximately the case for the Solar System, and the planets' orbits are also well-spaced. Planetoids like asteroids and TNO's and comets often have more eccentricity and inclination in their orbits.
But exoplanets have provided many surprises, like lots of warm and hot Jovian planets. It is hard for them to form when relatively close, so they must have spiraled in by interacting with the protoplanetary nebula. Another oddity is some of them having very eccentric orbits.
The authors found that higher metallicity tends to give higher eccentricities, and that the highest eccentricities are reached by Jupiter-mass planets at roughly 1 AU from their stars.
These results are fairly close to what one finds with simulations. These simulations included planets perturbing each others' orbits and colliding with each other. Larger planets perturb each other more, accounting for the high eccentriciies of the survivors. Higher metallicities mean more Jovian-planet nuclei, thus more Jovian planets.
From NASA Exoplanet Archive, the highest known eccentricity is form planet HD 20782 b : 0.950 +- 0.001
That planet orbits a star that is very much like the Sun. That star's distance is 36 parsecs or 117 light years, and its visual magnitude is around +7.4. One will need a telescope to see it. It is in constellation Fornax, the Furnace, with RA = 03h20m03.58s and Dec = -28d51m14.7s a sort of celestial longitude and latitude. It will be difficult to see from mid-northern latitudes, though much better from equatorial or mid-southern latitudes.
The planet's projected mass is 1.5 Jupiter masses, and its semimajor axis is 1.36 AU. Its closest and farthest distances are 0.068 and 2.65 AU. The planet's equilibrium temperatures at closest, major-axis, and farthest distances are 1134, 253, and 181 K, or 860, -20, and -92 C.
Its orbit period is 597.06 (Earth) days or 1.63 (Julian) years. But it is closer than twice its closest distance for only 4 days.
Meaning that large planets cannot coexist with each other very well, and I mean Jovian large, like Jupiter and Saturn.
The authors used stars' "metallicity" as a proxy for the amount of heavy elements in the stars' protoplanetary disks. "Heavy" being heavier than hydrogen and helium. Astrophysicists call all such heavy elements "metals". This is important because Jovian planets likely form from large icy or rocky planets, by collecting hydrogen and helium from the protoplanetary nebula.
Furthermore, one would expect planets to have circular and coplanar orbits. That is approximately the case for the Solar System, and the planets' orbits are also well-spaced. Planetoids like asteroids and TNO's and comets often have more eccentricity and inclination in their orbits.
But exoplanets have provided many surprises, like lots of warm and hot Jovian planets. It is hard for them to form when relatively close, so they must have spiraled in by interacting with the protoplanetary nebula. Another oddity is some of them having very eccentric orbits.
The authors found that higher metallicity tends to give higher eccentricities, and that the highest eccentricities are reached by Jupiter-mass planets at roughly 1 AU from their stars.
These results are fairly close to what one finds with simulations. These simulations included planets perturbing each others' orbits and colliding with each other. Larger planets perturb each other more, accounting for the high eccentriciies of the survivors. Higher metallicities mean more Jovian-planet nuclei, thus more Jovian planets.
From NASA Exoplanet Archive, the highest known eccentricity is form planet HD 20782 b : 0.950 +- 0.001
That planet orbits a star that is very much like the Sun. That star's distance is 36 parsecs or 117 light years, and its visual magnitude is around +7.4. One will need a telescope to see it. It is in constellation Fornax, the Furnace, with RA = 03h20m03.58s and Dec = -28d51m14.7s a sort of celestial longitude and latitude. It will be difficult to see from mid-northern latitudes, though much better from equatorial or mid-southern latitudes.
The planet's projected mass is 1.5 Jupiter masses, and its semimajor axis is 1.36 AU. Its closest and farthest distances are 0.068 and 2.65 AU. The planet's equilibrium temperatures at closest, major-axis, and farthest distances are 1134, 253, and 181 K, or 860, -20, and -92 C.
Its orbit period is 597.06 (Earth) days or 1.63 (Julian) years. But it is closer than twice its closest distance for only 4 days.