Vortex Fiber Nulling for Exoplanet Observations: Implementation and First Light

Vortex fiber nulling (VFN) is a single-aperture interferometric technique for detecting and characterizing exoplanets separated from their host star by less than a diffracted beam width. VFN uses a vortex mask and single mode fiber to selectively reject starlight while coupling off-axis planet light with a simple optical design that can be readily implemented on existing direct imaging instruments that can feed light to an optical fiber. With its axially symmetric coupling region peaking within the inner working angle of conventional coronagraphs, VFN is more efficient at detecting new companions at small separations than conventional direct imaging, thereby increasing the yield of on-going exoplanet search campaigns. We deployed a VFN mode operating in K band ($2.0{-}2.5~\mu$m) on the Keck Planet Imager and Characterizer (KPIC) instrument at the Keck II Telescope. In this paper we present the instrument design of this first on-sky demonstration of VFN and the results from on-sky commissioning, including planet and star throughput measurements and predicted flux-ratio detection limits for close-in companions. The instrument performance is shown to be sufficient for detecting a companion $10^3$ times fainter than a $5^{\mathrm{th}}$ magnitude host star in 1 hour at a separation of 50 mas (1.1$\lambda/D$). This makes the instrument capable of efficiently detecting substellar companions around young stars. We also discuss several routes for improvement that will reduce the required integration time for a detection by a factor ${>}$3.Comment: 26 pages, 5 figures; Accepted to JATI

The Visible Hands of Hierarchy within the M-Form: An Empirical Test of Corporate Parenting of Internal Product Exchanges

In this paper, we dismiss the traditional contingency argument that corporate staff should have minimal involvement with the decisions that its divisions make, because predictability, which underlies this contingency logic, is erroneous for most large corporations at this time. We offer an alternative theory of corporate involvement for the M-form: under unpredictable environments greater interdependence of corporate staff with divisional operating decisions may be necessary to create value for the corporation. Since corporate staff cannot be involved in all divisional affairs, we empirically explore when corporate involvement is most likely. Building on transaction cost economics and the strategy literature, we reason that corporate staff may selectively involve itself in business level strategy and operating decisions when product characteristics signal threats to effective inter-divisional coordination as well as opportunities for value creation. To explore this topic, we surveyed corporate managers of Fortune 500 companies. The results suggest some initial support for our theoretical argument: corporate staff is more likely to involve itself in business-level decisions for uncertain products. We further find that when corporate staff is responsible for the capital investments used for the divisional venture, it is more likely to guide and influence product strategy decisions and inter-divisional conflicts. We do not find, however, consistent evidence that specialized assets or brand-name reputation trigger corporate involvement. Implications and limitations are further discussed. Copyright 2003 Blackwell Publishing Ltd..