13,446 research outputs found
The Radio Jet Associated with the Multiple V380 Ori System
The giant Herbig-Haro object 222 extends over 6 in the plane of the
sky, with a bow shock morphology. The identification of its exciting source has
remained uncertain over the years. A non-thermal radio source located at the
core of the shock structure was proposed to be the exciting source. However,
Very Large Array studies showed that the radio source has a clear morphology of
radio galaxy and a lack of flux variations or proper motions, favoring an
extragalactic origin. Recently, an optical-IR study proposed that this giant HH
object is driven by the multiple stellar system V380 Ori, located about 23
to the SE of HH 222. The exciting sources of HH systems are usually detected as
weak free-free emitters at centimeter wavelengths. Here we report the detection
of an elongated radio source associated with the Herbig Be star or with its
close infrared companion in the multiple V380 Ori system. This radio source has
the characteristics of a thermal radio jet and is aligned with the direction of
the giant outflow defined by HH~222 and its suggested counterpart to the SE,
HH~1041. We propose that this radio jet traces the origin of the large scale HH
outflow. Assuming that the jet arises from the Herbig Be star, the radio
luminosity is a few times smaller than the value expected from the
radio-bolometric correlation for radio jets, confirming that this is a more
evolved object than those used to establish the correlation.Comment: 13 pages, 3 figure
A linear regression model for imprecise response
A linear regression model with imprecise response and p real explanatory variables is analyzed. The imprecision of the response variable is functionally described by means of certain kinds of fuzzy sets, the LR fuzzy sets. The LR fuzzy random variables are introduced to model usual random experiments when the characteristic observed on each result can be described with fuzzy numbers of a particular class, determined by 3 random values: the center, the left spread and the right spread. In fact, these constitute a natural generalization of the interval data. To deal with the estimation problem the space of the LR fuzzy numbers is proved to be isometric to a closed and convex cone of R3 with respect to a generalization of the most used metric for LR fuzzy numbers. The expression of the estimators in terms of moments is established, their limit distribution and asymptotic properties are analyzed and applied to the determination of confidence regions and hypothesis testing procedures. The results are illustrated by means of some case-studies. © 2010 Elsevier Inc. All rights reserved
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