Search results for "Solar Physic"

Die totale Sonnenfinsternis vom 8./21. August 1914 im Baltikum mit populären Erläuterungen dieses Phänomens [Die totale Sonnenfinsternis...im Baltiku…

1914

Detection of vortex tubes in solar granulation from observations with Sunrise

2010

We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory Sunrise. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that th…

Array programming with NumPy.

2020

Array programming provides a powerful, compact and expressive syntax for accessing, manipulating and operating on data in vectors, matrices and higher-dimensional arrays. NumPy is the primary array programming library for the Python language. It has an essential role in research analysis pipelines in fields as diverse as physics, chemistry, astronomy, geoscience, biology, psychology, materials science, engineering, finance and economics. For example, in astronomy, NumPy was an important part of the software stack used in the discovery of gravitational waves1 and in the first imaging of a black hole2. Here we review how a few fundamental array concepts lead to a simple and powerful programmi…

Solar and interplanetary triggers of the largest Dst variations of the solar cycle 23

2012

Abstract We present the results of an investigation from the Sun to the Earth of the sequence of events that caused major Dst decreases (Δ Dst ≤ – 100 nT during 1 h) that occurred during 1996–2005. These events are expected to be better related to geomagnetic induced current (GIC) events than those events where any geomagnetic index is far from its quiet time value. At least one full halo CME with a speed on the plane of sky above 900 km/s participates in every studied event. The seven events were triggered by interplanetary signatures, which arise as a consequence of interaction among different solar ejections. The interaction arises at different stages from the solar surface, between segm…

Enhanced detection of terrestrial gamma-ray flashes by AGILE

2015

Abstract At the end of March 2015 the onboard software configuration of the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite was modified in order to disable the veto signal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead time induced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma‐Ray Flashes (TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration (<100 μs), and part of them has simultaneous association with light…

The ‘Società degli Spettroscopisti Italiani’: birth and evolution

2008

Summary The anniversary of the death of Pietro Tacchini (1838–1905), one of the pioneers of solar physics in Italy, is commemorared by this account of his major creation, the Societa degli Spettroscopisti Italiani (1871). Established to promote cooperation among solar spectroscopists engaged in the study of the solar chromosphere, it was the first scientific Society devoted to spectroscopy and its astronomical applications. Its journal, the Memorie, collected most of the important works on solar physics by Angelo Secchi SJ (1818–1878), Tacchini himself, and many other protagonists of the newly born astrophysics. A brief history of the Society and its development draws on many previously une…

Probability and statistics

2013

PROMINENCE PLASMA DIAGNOSTICS THROUGH EXTREME-ULTRAVIOLET ABSORPTION

2013

In this paper we introduce a new diagnostic technique that uses prominence EUV and UV absorption to determine the prominence plasma electron temperature and column emission measure, as well as He/H relative abundance; if a realistic assumption on the geometry of the absorbing plasma can be made, this technique can also yield the absorbing plasma electron density. This technique capitalizes on the absorption properties of Hydrogen and Helium at different wavelength ranges and temperature regimes. Several cases where this technique can be successfully applied are described. This technique works best when prominence plasmas are hotter than 15,000 K and thus it is ideally suited for rapidly hea…

A synoptic view of solar transient evolution in the inner heliosphere using the Heliospheric Imagers on STEREO

2009

[1] By exploiting data from the STEREO/heliospheric imagers (HI) we extend a well-established technique developed for coronal analysis by producing time-elongation plots that reveal the nature of solar transient activity over a far more extensive region of the heliosphere than previously possible from coronagraph images. Despite the simplicity of these plots, their power in demonstrating how the plethora of ascending coronal features observed near the Sun evolve as they move antisunward is obvious. The time-elongation profile of a transient tracked by HI can, moreover, be used to establish its angle out of the plane-of-the-sky; an illustration of such analysis reveals coronal mass ejection …

A Dynamical Model for the Evolution of Hot Spots in Powerful Radio Sources

2003

AbstractCompact symmetric objects are considered the young counterparts of large doubles according to advance speeds measured or inferred from spectral ageing. Here we present a simple power law model for the CSO/FR II evolution based on the study of sources with well defined hot spots. The luminosity of the hot spots is estimated under minimum energy conditions. The advance of the source is considered to proceed in ram pressure equilibrium with the ambient medium. Finally, we also assume that the jets feeding the hot spots are relativistic and have a time dependent power. Comparison with observational data points to an interpretation of the CSO–FR II evolution in terms of decreasing jet po…