2,051 research outputs found
Discovery of a New Dusty B[e] Star in the Small Magellanic Cloud
We present new optical spectroscopic and archival Spitzer IRAC photometric
observations of a B-type star in the SMC cluster NGC 346, NGC 346:KWBBe 200. We
detect numerous Fe II, [O I], and [Fe II] lines, as well as strong P-Cygni
profile H I emission lines in its optical spectrum. The star's near-IR color
and optical to IR SED clearly indicate the presence of an infrared excess,
consistent with the presence of gas and warm, T ~800 K, circumstellar dust.
Based on a crude estimate of the star's luminosity and the observed
spectroscopic line profile morphologies, we find that the star is likely to be
a B-type supergiant. We suggest that NGC 346:KWBBe 200 is a newly discovered
B[e] supergiant star, and represents the fifth such object to be identified in
the SMC.Comment: 12 pages, accepted by Ap
Advanced mission analysis programs
Computer programs provide preliminary trajectory and guidance information required for feasibility studies in space mission analysis. The advanced mission analysis computer programs include programs for approximate solutions, programs for targeting and output, and programs for Monte Carlo and linear guidance analysis
Programmer's manual for the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)
The Mission Analysis Evaluation and Space Trajectory Operations program known as MAESTRO is described. MAESTRO is an all FORTRAN, block style, computer program designed to perform various mission control tasks. This manual is a guide to MAESTRO, providing individuals the capability of modifying the program to suit their needs. Descriptions are presented of each of the subroutines descriptions consist of input/output description, theory, subroutine description, and a flow chart where applicable. The programmer's manual also contains a detailed description of the common blocks, a subroutine cross reference map, and a general description of the program structure
Flight test results of the Strapdown hexad Inertial Reference Unit (SIRU). Volume 3: Appendices A-G
Results of flight tests of the Strapdown Inertial Reference Unit (SIRU) navigation system are presented. The fault tolerant SIRU navigation system features a redundant inertial sensor unit and dual computers. System software provides for detection and isolation of inertial sensor failures and continued operation in the event of failures. Flight test results include assessments of the system's navigational performance and fault tolerance. Selected facets of the flight tests are also described in detail and include some of the following: (1) flight test plans and ground track plots; (2) navigation residual plots; (3) effects of approximations in navigation algorithms; (4) vibration spectrum of the CV-340 aircraft; and (5) modification of the statistical FDICR algorithm parameters for the flight environment
Parameter estimation supplement to the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)
This Parameter Estimation Supplement describes the PEST computer program and gives instructions for its use in determination of lunar gravitation field coefficients. PEST was developed for use in the RAE-B lunar orbiting mission as a means of lunar field recovery. The observations processed by PEST are short-arc osculating orbital elements. These observations are the end product of an orbit determination process obtained with another program. PEST's end product it a set of harmonic coefficients to be used in long-term prediction of the lunar orbit. PEST employs some novel techniques in its estimation process, notably a square batch estimator and linear variational equations in the orbital elements (both osculating and mean) for measurement sensitivities. The program's capabilities are described, and operating instructions and input/output examples are given. PEST utilizes MAESTRO routines for its trajectory propagation. PEST's program structure and subroutines which are not common to MAESTRO are described. Some of the theoretical background information for the estimation process, and a derivation of linear variational equations for the Method 7 elements are included
Ultraviolet properties of IRAS-selected Be stars
New IUE observations were obtained of 35 Be stars from a list of stars which show excess infrared fluxes in IRAS data. The IRAS-selected Be stars show larger C IV and Si IV equivalent widths than other Be stars. Excess C IV and Si IV absorption seems to be independent of spectral type for IRAS-selected Be stars later than spectral type B4. This is interpreted as evidence for a possible second mechanism acting in conjunction with radiation pressure for producing the winds in Be stars. No clear correlation of IR excess of v sin i with C IV or Si IV equivalent widths is seen, although a threshold for the occurrence of excess C IV and Si IV absorption appears at a v sin i of 150 km/sec
Flight test results of the strapdown hexad inertial reference unit (SIRU). Volume 2: Test report
Results of flight tests of the Strapdown Inertial Reference Unit (SIRU) navigation system are presented. The fault tolerant SIRU navigation system features a redundant inertial sensor unit and dual computers. System software provides for detection and isolation of inertial sensor failures and continued operation in the event of failures. Flight test results include assessments of the system's navigational performance and fault tolerance. Performance shortcomings are analyzed
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