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Apsidal Alignment in Upsilon Andromedae

One of the parameters fitted by Doppler radial velocity measurements of extrasolar planetary systems is ω, the argument of pericenter of a given planet’s orbit referenced to the plane of the sky. Curiously, the ω’s of the outer two planets orbiting Upsilon Andromedae are presently nearly identical: ∆ω ≡ ωD − ωC = 4. 8 ± 4. 8 (1σ). This observation is least surprising if planets C and D occupy o...

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This paper presents lessons learned during the development of NASA's Systems Test and Operations Language (STOL) Intelligent Tutoring System (ITS), being developed at NASA Goddard Space Flight Center with support by Carlow Associates Incorporated and Computer Sciences Corporation. The purpose of the intelligent tutor is to train STOL users by adapting tutoring based on inferred student strength...

Habitability in the Upsilon Andromedae System

We investigate the habitability of the Upsilon Andromedae planetary system as it evolves from a hypothetical four-planet system into what is observed today. We initially considered a fourth planet at a distance of 4.76 AU from the central star. We simulated the dynamics of this system until the fourth planet was ejected due to gravitational interactions with the other planets. Results demonstra...

The Upsilon Andromedae System: Models and Stability

Radial velocity observations of the F8 V star υ Andromedae taken at Lick and at Whipple Observatories have revealed evidence of three periodicities in the line-ofsight velocity of the star. These periodicities have been interpreted as evidence for at least three low mass companions (LMCs) revolving around υ Andromedae. The mass and orbital parameters inferred for these companions raise question...