4 research outputs found
Discovery of a weak magnetic field in the photosphere of the single giant Pollux
Aims: We observe the nearby, weakly-active single giant, Pollux, in order to
directly study and infer the nature of its magnetic field. Methods: We used the
new generation spectropolarimeters ESPaDOnS and NARVAL to observe and detect
circular polarization within the photospheric absorption lines of Pollux. Our
observations span 18 months from 2007-2009. We treated the spectropolarimetric
data using the Least-Squares Deconvolution method to create high
signal-to-noise ratio mean Stokes V profiles. We also measured the classical
activity indicator S-index for the Ca H&K lines, and the stellar radial
velocity (RV). Results: We have unambiguously detected a weak Stokes V signal
in the spectral lines of Pollux, and measured the related surface-averaged
longitudinal magnetic field Bl. The longitudinal field averaged over the span
of the observations is below one gauss. Our data suggest variations of the
longitudinal magnetic field, but no significant variation of the S-index. We
observe variations of RV which are qualitatively consistent with the published
ephemeris for a proposed exoplanet orbiting Pollux. The observed variations of
Bl appear to mimic those of RV, but additional data for this relationship to be
established. Using evolutionary models including the effects of rotation, we
derive the mass of Pollux and we discuss its evolutionary status and the origin
of its magnetic field. Conclusions: This work presents the first direct
detection of the magnetic field of Pollux, and demonstrates that ESPaDOnS and
NARVAL are capable of obtaining sub-G measurements of the surface-averaged
longitudinal magnetic field of giant stars, and of directly studying the
relationships between magnetic activity, stellar evolution and planet hosting
of these stars.Comment: 8 pages, 6 figures, accepted for publication in Astronomy and
Astrophysic
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The Existential Crisis in PĂo Baroja and Fyodor Dostoevsky: The novel as the vehicle for the analysis of national and spiritual distress.
The Existential Crisis in PĂo Baroja and Fyodor Dostoevsky: The novel as the vehicle for the analysis of national and spiritual distress contributes to the field of Spanish literature by analyzing the links between the works of two of the world’s most important novelists, PĂo Baroja and Fyodor Dostoevsky, during moments of national and international crisis and transformation. As part of the examination into the utilization of the novel to address social, political, and individual crisis, my research addresses PĂo Baroja and Fyodor Dostoevsky’s unique programs for individual totality within the context of an abundance of propositions for societal restoration. My study provides a historical background for both countries with respect to philosophical and social ideologies, including the movements of positivism, Krausism, and the introduction of La InstituciĂłn Libre de Enseñanza in Spain, and feudalism, westernization, and the corresponding political developments in Russia. Both Dostoevsky and Baroja reject programs for societal remediation on the basis of an unrelenting preference for individualism, exemplified in many of the protagonists of their works. Baroja’s novels El árbol de la ciencia, Mala hierba, Camino de perfecciĂłn (PasiĂłn mĂstica), Aurora roja, CĂ©sar o nada, and ZalacaĂn el aventurero, along with Dostoevsky’s novels The Gambler, Notes from the Underground, The Brothers Karamazov, and Crime and Punishment, denote a shared view of the impossibility of achieving total individual fulfillment in life, but they differ in their proposals to address this problem. Baroja suggests an amalgamation between reason and vitality, with preference given to individual vitality due to its power to sustain life and inspire action. Dostoevsky advances the acceptance of Jesus Christ as one’s savior, in accordance with his adherence to Eastern Orthodox Christianity, and an embrace of suffering to confirm one’s individuality. In addition to depicting their respective programs, their novels serve as a vehicle to penetrate the structure of dominant ideological systems. While researchers have established a general connection between Baroja and Dostoevsky, my research seeks to expand and develop the previous relevant literature by presenting a wholistic overview of their programs advanced in their novels
Pointing Control for Low Altitude Triple Cubesat Space Darts
Pointing control of cubesats can be quite challenging due to constraints on volume, cost, and complexity of control hardware. Recent achievements and developments in small sensor and actuator designs have enabled the possibility of reasonable pointing performance (a few degrees or better) for a variety of intriguing space experiments. In this paper we describe a simple pointing control design that exploits the aerodynamics associated with the space dart geometry of a triple cubesat with deployable solar panels in a low-altitude orbit (\u3c 500 km) to provide passive pitch and yaw stabilization, coupled with a small momentum-biased pitch reaction wheel offering passive yaw and roll stabilization. Augmented active rate damping is provided using a small three-axis magnetometer, three small magnetic torquers, and a model-based B-dot control law. This simple passive/active control system offers experiment pointing capability to less than 5 degrees of nadir without the need for any attitude knowledge