Evidence for Multiple Companions to υ Andromedae

Butler, R. Paul; Marcy, Geoffrey W.; Fischer, Debra A.; Brown, Timothy M.; Contos, Adam R.; Korzennik, S. G.; Nisenson, P.; Noyes, R. W.

doi:10.1086/308035

Cited by 311 publications

(222 citation statements)

References 44 publications

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“…This is a hybrid mechanism because the required planetary migration is driven by an underlying disk, while each planet's eccentricity is directly excited by the other planet. A different hybrid scenario may have played out for planet C in the system Upsilon Andromedae (Butler et al 1999;Chiang, Tabachnik, & Tremaine 2001b). A primordial disk may have directly excited the eccentricity of the outermost planet, D; secular interactions between D and C could then have siphoned off the eccentricity of the former to grow that of the latter (Chiang & Murray 2002).…”

Section: Introductionmentioning

confidence: 99%

Excitation of Orbital Eccentricities by Repeated Resonance Crossings: Requirements

Chiang

2003

ApJ

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Divergent migration of planets within a viscous circumstellar disk can engender resonance crossings and dramatic excitation of orbital eccentricities. We provide quantitative criteria for the viability of this mechanism. For the orbits of two bodies to diverge, a ring of viscous material must be shepherded between them. As the ring diffuses in radius by virtue of its intrinsic viscosity, the two planets are wedged farther apart. The ring mass must be smaller than the planetary masses so that the crossing of an individual resonance lasts longer than the resonant libration period. At the same time, the resonance crossing cannot be of such long duration that the disk's direct influence on the bodies' eccentricities interferes with the resonant interaction between the two planets. This last criterion is robustly satisfied because resonant widths are typically tiny fractions of the orbital radius. We evaluate our criteria not only for giant planets within gaseous protoplanetary disks but also for shepherd moons that bracket narrow planetary rings in the solar system. A shepherded ring of gas orbiting at a distance of 1 AU from a solar-type star and having a surface density of less than 500 g cm À2 , a dimensionless alpha viscosity of 0.1, and a height-to-radius aspect ratio of 0.05 can drive two Jupiter-mass planets through the 2 : 1 and higher order resonances so that their eccentricities amplify to values of several tenths. Because of the requirement that the disk mass in the vicinity of the planets be smaller than the planet masses, divergent resonance crossings may figure significantly into the orbital evolution of planets during the later stages of protoplanetary disk evolution, including the debris disk phase.

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Section: Introductionmentioning

confidence: 99%

Excitation of Orbital Eccentricities by Repeated Resonance Crossings: Requirements

Chiang

2003

ApJ

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“…We note that the extrasolar planets discovered thus far (e.g., Mayor & Queloz 1995;Marcy & Butler 1996;Butler et al 1999;Marcy et al 2001) have masses near that of Jupiter and are thus thought to be gaseous giant planets. Although terrestrial planets have not been detected in extrasolar systems with main-sequence primaries due to their small masses, they are expected to readily form in such systems alongside their Jovian counterparts (e.g., Lissauer 1993).…”

Section: Terrestrial Planet Formation In Binary Systemsmentioning

confidence: 80%

“…The extrasolar planets detected thus far (again, see Mayor & Queloz 1995;Marcy & Butler 1996;Butler et al 1999;Marcy et al 2001) have apparently moved from their birth locations in the outer nebula and now reside in rather unusual orbits, with small semi-major axes a and large eccenticities . An important challenge for planet formation theories is to account for this migration phenomenon.…”

Section: Giant Planet Migrationmentioning

confidence: 89%

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Formation, migration, and stability of extrasolar planetary systems

Adams¹

2004

Proc. IAU

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Abstract. This paper presents recent results concerning the planet formation, planet migration, and the long term stability of planetary systems. Most stars are found in binary systems and binary companions can disrupt both planet formation and stability. We first consider the effects of outer binary companions on the late stages of terrestrial planet formation and show how planet formation depends on the binary periastron. We then consider migration mechanisms for giant planets. In this case, planet scattering produces the full range of orbital eccentricities, but is less effective in moving planets inward (decreasing their semi-major axes). Disk torques are effective at moving planets inward, but not at increasing the eccentricities. We explore a scenario in which disk torques act in concert with planet scattering to provide the full range of orbital elements observed in extrasolar planetary systems. Finally, we consider the longer term stability of Earth-like planets in binary systems; we find that nearly 50 percent of binaries allow for Earth-like planets to remain stable over the current (4.6 Gyr) age of our solar system.

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“…First, the Upsilon Andromedae triple planet system (Butler et al 1999) is highly significant because there are no stellar systems known to consist of a massive primary orbited by three smaller stars. Second, the discovery of the first transiting planet, on a short period orbit around HD 209458 (Charbonneau et al 2000;Henry et al 2000), provided a further argument that at least some of these objects are gas giant planets: the transiting planet's mass is~0.7M J up, and its radius of~1.4RJup (Mazeh et al 2000) is in good agreement with theoretical expectations for a hot Jupiter (Burrows et al 2000).…”

Section: Modes Of Gaseous Planet Formationmentioning

confidence: 99%

Modes of Gaseous Planet Formation

Boss

2004

Symp. - Int. Astron. Union

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Abstract.The discovery of gas giant planets around nearby stars has launched a new era in our understanding of the formation and evolution of planetary systems. However, none of the over four dozen companions detected to date strongly resembles Jupiter or Saturn: their inferred masses range from sub-Saturn-mass to 10 Jupiter-masses or more, while their orbits extend from periods of a few days to a few years. Given this situation, it seems prudent to re-examine mechanisms for gas giant planet formation. The two extreme cases are top-down or bottom-up. The latter is the core accretion mechanism, long favored for our Solar System, where a roughly 10 Earth-mass solid core forms by collisional accumulation of planetesimals, followed by hydrodynamic accretion of a gaseous envelope. The former is the long-discarded disk instability mechanism, where the protoplanetary disk forms self-gravitating, gaseous protoplanets through a gravitational instability of the gas, accompanied by settling and coagulation of dust grains to form solid cores. Both of these mechanisms have a number of advantages and disadvantages, making a purely theoretical choice between them difficult at present. Observations should be able to decide the dominant mechanism by dating the epoch of gas giant planet formation: core accretion requires more than a million years to form a Jupiter-mass planet, whereas disk instability is much more rapid.

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Evidence for Multiple Companions to υ Andromedae

Cited by 311 publications

References 44 publications

Excitation of Orbital Eccentricities by Repeated Resonance Crossings: Requirements

Excitation of Orbital Eccentricities by Repeated Resonance Crossings: Requirements

Formation, migration, and stability of extrasolar planetary systems

Modes of Gaseous Planet Formation

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