Early light curves for Type Ia supernova explosion models

Upcoming high-cadence transient survey programmes will produce a wealth of observational data for Type Ia supernovae. These data sets will contain numerous events detected very early in their evolution, shortly after explosion. Here, we present synthetic light curves, calculated with the radiation hydrodynamical approach Stella for a number of different explosion models, specifically focusing on these first few days after explosion. We show that overall the early light curve evolution is similar for most of the investigated models. Characteristic imprints are induced by radioactive material located close to the surface. However, these are very similar to the signatures expected from ejecta-CSM or ejecta-companion interaction. Apart from the pure deflagration explosion models, none of our synthetic light curves exhibit the commonly assumed power-law rise. We demonstrate that this can lead to substantial errors in the determination of the time of explosion. In summary, we illustrate with our calculations that even with very early data an identification of specific explosion scenarios is challenging, if only photometric observations are available.Comment: 15 pages, 14 figures, 3 tables, accepted for publication in MNRA

Three-dimensional simulations of the interaction between Type Ia supernova ejecta and their main sequence companions

The identity of the progenitor systems of SNe Ia is still uncertain. In the single-degenerate (SD) scenario, the interaction between the SN blast wave and the outer layers of a main sequence (MS) companion star strips off H-rich material which is then mixed into the ejecta. Strong contamination of the SN ejecta with stripped material could lead to a conflict with observations of SNe Ia. This constrains the SD progenitor model. In this work, our previous simulations based on simplified progenitor donor stars have been updated by adopting more realistic progenitor-system models that result from fully detailed, state-of-the-art binary evolution calculations. We use Eggleton's stellar evolution code including the optically thick accretion wind model and the possibility of the effects of accretion disk instabilities to obtain realistic models of companions for different progenitor systems. The impact of the SN blast wave on these companion stars is followed in three-dimensional hydrodynamic simulations employing the SPH code GADGET3. We find that the stripped masses range from 0.11 to 0.18 M_sun. The kick velocity is between 51 and 105 km/s. We find that the stripped mass and kick velocity depend on the ratio of the orbital separation to the radius of a companion. They can be fitted by a power law for a given companion model. However, the structure of the companion star is also important for the amount of stripped material. With more realistic companion star models than in previous studies, our simulations show that the H masses stripped from companions are inconsistent with the best observational limits (< 0.01 M_sun) derived from nebular spectra. However, a rigorous forward modeling based on impact simulations with radiation transfer is required to reliably predict observable signatures of the stripped H and to conclusively assess the viability of the considered SN Ia progenitor scenario.Comment: 14 pages, 13 figures, accepted for publication by A&

Group 62 Section Leaders Meeting, July 26, 1954

Effective use of Lincoln manpower contemplates the use of small groups in certain areas and reinforcement of personnel in other areas of activity; namely the Systems Office, Frame Testing, and Duplex Planning. Marginal checking system to be reviewed to determine if degree to which the philosophy has been carried out has not resulted in too elaborate a system. Electronic circuits for display consoles are to be processed through EDO-SO for concurrence and release. A group of people intimately familiar with the electronic hardware will study the programming of the machine to evaluate the compatibility of the equipment and programs. Later schedules for display call for construction of central display frame in November and December of 1954

Transmittal of Publications to IBM

Uniform procedure for transmittal of M-Memos, E-Notes and other publications of IBM is important. This memo indicates a procedure for handling this type of activity

IBM Project HIGH Engineering Organization

This memorandum provides information on the organization of Project HIGH as of Aug. 1, 1953

Conference regarding proposed modification to delivery schedule for AN/FSQ-7 duplex centrals - June 9 and 10, 1954

Includes an attendance list and full-page diagram.Proceedings of a conference called by the AMC Joint Progress Office to discuss the proposed modification to the delivery schedule for AN/FSQ-7 duplex centrals. The agenda surrounded the following topics: field trials for performance evaluation test under field conditions, field trial facilities, interim production effort, large scale production, and the revised schedule

Group 62 Section Leaders Meeting--August 23, 1954

Concurrence with IBM is scheduled for display system and MRI specifications. MTC has been reassembled and will be fully operational by September 1. Components of the 13 most frequently used circuits are to be released for ordering (for 2 Production Systems) in September. First floor equipment layout for production systems is being finalized. Requirements for Power System for production system has been released through the Production Coordination Office

Group 62 Section Leaders Meeting -- December 14, 1953

SDV demodulator circuitry has been reviewed and accepted. Phone line transmission characteristics are being determined in conjunction with Bell Laboratories Project ADES personnel. Simplification of equipment to handle inputs having a relatively slow data rate is under study. Coordination of output system and equipment development is to be done by a joint IBM--Div. 6--Div 2 committee. Formalizing of the release for design completion and for construction of the two prototype systems is to be outlined in M-2575. Operational aspects of the display equipment for both Direction Center and Combat Center are being considered jointly by Lincoln, ADES and ADC

Summary of IBM - MIT Collaboration, April 1, 1953 to April 27, 1953 inclusive

This period represents the sixth month of the Subcontract between MIT and IBM. The original contract termination date was April 27, 1953. Through an amendment this has been extended to July 31, 1953 to permit purchase and delivery of additional test equipment by IBM. Engineering development work will, however, be financed through a prime contract between IBM and AFCRC in the future

Summary of IBM - MIT Collaboration, January 1, 1953 to January 31, 1953 inclusive

The third month of the interval covered by the Subcontract between MIT and IBM has continued discussions regarding engineering aspects of the Air Defense problem. Principle among these has been the proposal made by IBM concerning the design of an arithmetic element for Whirlwind II. Subsequent discussions have resulted in tentative decisions to have a 32-bit word length, with the arithmetic element capable of working as a single unit or split so that it can work on two 16-bit words simultaneously