Against all odds? Forming the planet of the HD196885 binary

Details Against all odds? Forming the planet of the HD196885 binary Against all odds? Forming the planet of the HD196885 binary

2011-03-20

arxiv.org/abs/1103.3900v1

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

accepted for publication by Celestial Mechanics and Dynamical Astronomy (Special issue on EXOPLANETS)

Scientific paper

HD196885Ab is the most "extreme" planet-in-a-binary discovered to date, whose orbit places it at the limit for orbital stability. The presence of a planet in such a highly perturbed region poses a clear challenge to planet-formation scenarios. We investigate this issue by focusing on the planet-formation stage that is arguably the most sensitive to binary perturbations: the mutual accretion of kilometre-sized planetesimals. To this effect we numerically estimate the impact velocities $dv$ amongst a population of circumprimary planetesimals. We find that most of the circumprimary disc is strongly hostile to planetesimal accretion, especially the region around 2.6AU (the planet's location) where binary perturbations induce planetesimal-shattering $dv$ of more than 1km/s. Possible solutions to the paradox of having a planet in such accretion-hostile regions are 1) that initial planetesimals were very big, at least 250km, 2) that the binary had an initial orbit at least twice the present one, and was later compacted due to early stellar encounters, 3) that planetesimals did not grow by mutual impacts but by sweeping of dust (the "snowball" growth mode identified by Xie et al., 2010b), or 4) that HD196885Ab was formed not by core-accretion but by the concurent disc instability mechanism. All of these 4 scenarios remain however highly conjectural.

Affiliated with

Also associated with

No associations

Rating

Against all odds? Forming the planet of the HD196885 binary does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Against all odds? Forming the planet of the HD196885 binary, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Against all odds? Forming the planet of the HD196885 binary will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-322258