1,788 research outputs found
Observations of young low-mass stars in dense cores
In this period the first maps were made during two flights of the Kuipper Airborne Observatory (KAO) in January 1986. One of these shows extended emission at 100 and 160 microns from the dense core B35 containing the IRAS point source 05417+0907. The 160 micron emission has approximately the same extent as the NH3 (1,1) line emission at 1.4 cm, indicating close correspondence between the warm dust and the dense gas. The 160 micron map shows a previously unknown secondary maximum about 90 arcsec north of the IRAS source
Flight dynamics system software development environment (FDS/SDE) tutorial
A sample development scenario using the Flight Dynamics System Software Development Environment (FDS/SDE) is presented. The SDE uses a menu-driven, fill-in-the-blanks format that provides online help at all steps, thus eliminating lengthy training and allowing immediate use of this new software development tool
String Matching with Variable Length Gaps
We consider string matching with variable length gaps. Given a string and
a pattern consisting of strings separated by variable length gaps
(arbitrary strings of length in a specified range), the problem is to find all
ending positions of substrings in that match . This problem is a basic
primitive in computational biology applications. Let and be the lengths
of and , respectively, and let be the number of strings in . We
present a new algorithm achieving time and space , where is the sum of the lower bounds of the lengths of the gaps in
and is the total number of occurrences of the strings in
within . Compared to the previous results this bound essentially achieves
the best known time and space complexities simultaneously. Consequently, our
algorithm obtains the best known bounds for almost all combinations of ,
, , , and . Our algorithm is surprisingly simple and
straightforward to implement. We also present algorithms for finding and
encoding the positions of all strings in for every match of the pattern.Comment: draft of full version, extended abstract at SPIRE 201
Observational and Theoretical Studies of Low-Mass Star Formation
Under this grant we have pursued studies of low-mass star formation with observations of candidate star-forming regions, (1) to determine the incidence of "infall asymmetry" in the spectral lines from very red young stellar objects; (2) to make detailed maps of candidate infall regions to determine the spatial extent of their infall asymmetry; (3) to compare the spatial and velocity structure of candidate infall regions with single dish and interferometer resolution; and (4) to begin a program of observations of starless dense cores to detect the presence or absence of infall motions
Internal Motions in Starless Dense Cores
This paper discusses the statistics of internal motions in starless dense
cores and the relation of these motions to core density and evolution. Four
spectral lines from three molecular species are analyzed from single-pointing
and mapped observations of several tens of starless cores. Blue asymmetric
profiles are dominant, indicating that inward motions are prevalent in
sufficiently dense starless cores. These blue profiles are found to be more
abundant, and their asymmetry is bluer, at core positions with stronger line emission or higher column density. Thirty three starless cores are
classified into four types according to the blue and red shifts of the lines in
their molecular line maps. Among these cores, contracting motions dominate: 19
are classified as contracting, 3 as oscillating, 3 as expanding, and 8 as
static. Contracting cores have inward motions all over the core with
predominance of those motions near the region of peak density. Cores with the
bluest asymmetry tend to have greater column density than other cores and all
five cores with peak column density are found
to be contracting. This suggests that starless cores are likely to have
contracting motions if they are sufficiently condensed. Our classification of
the starless cores may indicate a sequence of core evolution in the sense that
column density increases from static to contracting cores: the static cores in
the earliest stage, the expanding and/or the oscillating cores in the next, and
the contracting cores in the latest stage.Comment: Accepted for publication in The Astrophysical Journal, 34 pages, and
14 figure
Microwave Thermography
Contains research objectives and summary of research on one research project.National Institutes of Health (Grant 5 R01 GM20370-04)National Institutes of Health (Grant 5 SO5 RR07047-l1
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