Precession of collimated outflows from young stellar objects

Astrophysical Journal 512:2 PART 2 (1999)

Authors:

C Terquem, J Eislöffel, JCB Papaloizou, RP Nelson

Abstract:

We consider several protostellar systems in which either a precessing jet or at least two misaligned jets have been observed. We assume that the precession of jets is caused by tidal interactions in noncoplanar binary systems. For Cep E, V1331 Cyg, and RNO 15-FIR, the inferred orbital separations and disk radii are in the range 4-160 AU and 1-80 AU, respectively, consistent with those expected for pre-main-sequence stars. Furthermore, we assume or use the fact that the source of misaligned outflows is a binary and evaluate the length scale over which the jets should precess as a result of tidal interactions. For T Tau, HH1 VLA 1/2, and HH 24 SVS63, it may be possible to detect a bending of the jets rather than "wiggling." In HH 111 IRS and L1551 IRS5, wiggling may be detected on the current observed scale. Our results are consistent with the existence of noncoplanar binary systems in which tidal interactions induce jets to precess.

POD analysis of baroclinic wave flows in the thermally-driven, rotating annulus experiment

Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere 24:5 (1999) 449-453

Authors:

AV Stephen, IM Moroz, PL Read

Abstract:

The Proper Orthogonal Decomposition (POD) is a procedure to compute an orthogonal basis from a time series of spatial fields. This basis is optimal among all linear decompositions, in the sense that for a given number of modes, the projection of the original signal onto the subspace will contain the most variance on average. This algorithm is applied to streamfunction fields derived from measurements of the flow in the thermally forced rotating annulus experiment. Results of this analysis are presented, and a method to derive low-dimensional models of the flow by projecting the equations of motion onto these empirical eigenfunctions is discussed.

A climate database for Mars

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS 104:E10 (1999) 24177-24194

Authors:

SR Lewis, M Collins, PL Read, F Forget, F Hourdin, R Fournier, C Hourdin, O Talagrand, JP Huot

Critical protoplanetary core masses in protoplanetary disks and the formation of short-period giant planets

Astrophysical Journal 521:2 PART 1 (1999) 823-838

Authors:

JCB Papaloizou, C Terquem

Experiments on a barotropic rotating shear layer.: Part 1.: Instability and steady vortices

JOURNAL OF FLUID MECHANICS 383 (1999) 143-173

Authors:

WG Früh, PL Read