Ellipsoidal variation in EG Andromedae

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...

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 Dwarf Nova Pq Andromedae

Line profile variation and planets around 51 Pegasi and υ Andromedae ?

We report results of high resolution spectroscopic observations of the stars 51 Peg and υ And. Variations in the shape of different lines are studied in the light of a recent controversy concerning the existence of a planet orbiting around 51 Peg. Bisector variations have been noticed for both stars, their shapes and variations are not easily understood, but they do not indicate any interpretat...

Planet–Planet Scattering in Upsilon Andromedae

Doppler spectroscopy has detected 136 planets around nearby stars. A major puzzle is why their orbits are highly eccentric, while all planets in our Solar System are on nearly circular orbits, as expected if they formed by accretion processes in a protostellar disk. Several mechanisms have been proposed to generate large eccentricities after planet formation, but so far there has been little ob...