Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters.

Eighteen small (4 arc-min square) fields within the Orion Nebula Cluster (ONC) have been photometrically monitored for one or more observing seasons between 1990 and 1999 with a CCD attached to the 0.6 m telescope at Van Vleck Observatory on the campus of Wesleyan University. Data were obtained exclusively in the Cousins I band on between 25 and 40 nights per season. Results from the first thre...

The nineteenth western meeting of the Society being the fifty-first regular meeting of the Chicago Section, was held at the University of Chicago on Friday and Saturday, April 13 and 14, 1923. There were about eighty persons present at this meeting, among them the following sixty members of the Society: Ballantine, E. M. Berry, Bliss, Blumberg, Brahana, Brink, C. C. Camp, Coble, Copenhaver, H. ...

We examine the detectability and interpretation of debris trails caused by satellite disruption in external galaxies using semi-analytic approximations for the dependence of streamer length, width and surface brightness on satellite and primary galaxy characteristics. The semi-analytic method is tested successfully against N-body simulations and then applied to three representative astronomical...

In the recent new edition of the collected works of T.J. Stieltjes, one of us gave an impression of the impact of Stieltjes' work a century after his death 43]. In this paper we give an update and mention some observations which were missing from 43] and some results which appeared during the last two years and which are directly related to Stieltjes' work. In particular there is a large sectio...

ellis-van creveld sydrome (chondroectodermal dysplasia) is a hereditary form of short limb disproportionate dwarfism characterized by diffuse involvement of skeletal system and visceral organs. two brothers affected by this syndrome are presented here following a brief account of the disease's manifestations.

In the theory of anharmonic vibrations of a polyatomic molecule, mixing the zero-order vibrational states due to cubic, quartic and higher-order terms in the potential energy expansion leads to the appearance of more-or-less isolated blocks of states (also called polyads), connected through multiple resonances. Such polyads of states can be characterized by a common secondary integer quantum nu...

We consider the problem of computing the global response of a tokamak to RF-antenna driving, including conversion at the ion-hybrid resonance layer. The tokamak is modeled as a 2-D circular cavity (a poloidal cross-section). An antenna launches a family of magnetosonic (MS) rays. The amplitude and phase of the MS wave eld are transported using eikonal techniques: the phase is transported using ...

We present the results of a high-resolution spectroscopic monitoring program of the eclipsing pre–main-sequence star KH 15D that reveal it to be a single-line spectroscopic binary. We find that the best-fit Keplerian model has a period P = 48.38 days, which is nearly identical to the photometric period. Thus, we find the best explanation for the periodic dimming of KH 15D is that the binary mot...