We report on the discovery of at least 18 pulsation modes in β Pictoris from 697 high‐dispersion spectra obtained over a two‐week period. These are seen as absorption subfeatures moving across the spectral line profiles, indicating that they are of relatively high spherical harmonic order. They do not resemble the features seen in the Ca H and K lines generally attributed to infalling bodies. We use the correlation function between an unbroadened synthetic spectrum and the observed spectrum to obtain what is essentially a high signal‐to‐noise ratio representation of the mean line profile. From the correlation intensity as a function of time, we calculated periodograms for every point across the correlation function. In this way, we are able to determine accurate periods for each mode. By phasing the correlation function with the period belonging to a given mode, we can isolate the line profile variations for the mode and deduce the approximate value of the azimuthal order, m. Two of the modes are retrograde, the remainder are prograde and most of them lie in the range 4 ≤|m|≤ 10. Comparison with non‐adiabatic models shows that the periods are in the range expected for unstable modes in a star with the mass and temperature appropriate to β Pic. Some constraints can be placed on the effective temperature. We also report on photometric observations of β Pic obtained during the same run. From our 14 318 photometric observations combined with the discovery data from Koen (2003), we find two definite pulsation modes with frequencies of 47.4 and 38.1 cycle d−1. A third frequency at 47.3 cycle d−1 may also be present. The amplitudes are all smaller than 1.5 mmag.

Abstract:We construct the giant graviton on AdS 4 × CP 3 out of a four-brane embedded in and moving on the complex projective space. This configuration is dual to the totally anti-symmetric Schur polynomial operator χ R (A 1 B 1 ) in the 2+1-dimensional, N = 6 super Chern-Simons ABJM theory. We demonstrate that this BPS solution of the D4-brane action is energetically degenerate with the point graviton solution and initiate a study of its spectrum of small fluctuations. Although the full computation of this spectrum proves to be analytically intractable, by perturbing around a "small" giant graviton, we find good evidence for a dependence of the spectrum on the size, α 0 , of the giant. This is a direct result of the changing shape of the worldvolume as it grows in size.

In this article we consider gauge theories with a U (N ) × U (N ) gauge group. We provide, for the first time, a complete set of operators built from scalar fields that are in the bi fundamental of the two groups. Our operators diagonalize the two point function of the free field theory at all orders in 1/N . We then use this basis to investigate non-planar anomalous dimensions in the ABJM theory. We show that the dilatation operator reduces to a set of decoupled harmonic oscillators, signaling integrability in a large N but non-planar limit of the theory.