Hot jupiters from coplanar high-eccentricity migration
- Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08544 (United States)
We study the possibility that hot Jupiters (HJs) are formed through the secular gravitational interactions between two planets in eccentric orbits with relatively low mutual inclinations (≲20{sup ∘}) and friction due to tides raised on the planet by the host star. We term this migration mechanism Coplanar High-eccentricity Migration (CHEM) because, like disk migration, it allows for migration to occur on the same plane in which the planets formed. CHEM can operate from the following typical initial configurations: (i) the inner planet in a circular orbit and the outer planet with an eccentricity ≳0.67 for m{sub in}/m{sub out}(a{sub in}/a{sub out}){sup 1/2}≲0.3; (ii) two eccentric (≳0.5) orbits for m{sub in}/m{sub out}(a{sub in}/a{sub out}){sup 1/2}≲0.16. A population synthesis study of hierarchical systems of two giant planets using the observed eccentricity distribution of giant planets shows that CHEM produces HJs with low stellar obliquities (≲30{sup ∘}), with a semi-major axis distribution that matches the observations, and at a rate that can account for their observed occurrence. A different mechanism is needed to create large obliquity HJs, either a different migration channel or a mechanism that tilts the star or the protoplanetary disk. CHEM predicts that HJs should have distant (a≳5 AU) and massive (most likely ∼1–3 times more massive than the HJ) companions with relatively low mutual inclinations (≲20{sup ∘}) and moderately high eccentricities (e∼0.2−0.5).
- OSTI ID:
- 22883170
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 805; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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