scholarly journals The Need for High Resolution for Polarization Studies of Galactic Background Radiation

1990 ◽  
Vol 140 ◽  
pp. 62-62
Author(s):  
G.L. Verschuur ◽  
T. A. Th. Spoelstra
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Background Radiation ◽  
Limited Data ◽  
Polarization Data ◽  
The North ◽  
Polarization Studies ◽  
North Polar ◽  
Galactic Background ◽  
Scale Length

Polarization data at 390 and 826 MHz were obtained with the 300-foot telescope in February 1987. A survey of selected regions of sky planned for December 1988 had to be postponed. However, our limited data at 390 MHz show that the 30′ beam detected polarization temperatures between four to six times larger than found in surveys with a 1.3 arcmin resolution. This was true in both the highly polarized region around 1=140 degrees and in the North Polar Spur where polarization structures appear to be unresolved (<0.9 pc at the distance of the spur). High resolution observations will be critical to our understanding of the interstellar magnetic field and the scale-length of depolarizing structures.

scholarly journals A High-Resolution Polarization Survey of the North Polar Spur

1974 ◽  
Vol 60 ◽  
pp. 151-154
Author(s):  
G. Westerhout ◽  
D. Bechis
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
High Resolution ◽  
Polarization Distribution ◽  
The North ◽  
Angular Scale ◽  
North Polar ◽  
The Magnetic Field

Observations have been made at 21 cm with a resolution of 11′ to look for fine structure in the polarization distribution. In the North Polar Spur, the angular scale of the polarization parameters varies with latitude. This is attributed to an increase in the irregularity of the magnetic field in the Spur with latitude.

scholarly journals Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

2021 ◽  
Vol 922 (2) ◽  
pp. 210
Author(s):  
G. V. Panopoulou ◽  
C. Dickinson ◽  
A. C. S. Readhead ◽  
T. J. Pearson ◽  
M. W. Peel
Keyword(s):  
Magnetic Field ◽  
Galactic Center ◽  
Classical Method ◽  
Dust Emission ◽  
Galactic Latitude ◽  
Synchrotron Emission ◽  
Optical Polarization ◽  
The North ◽  
Significant Alignment ◽  
North Polar

Abstract Galactic synchrotron emission exhibits large angular scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either under debate or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions toward Loop I of 112 ± 17 pc, 135 ± 20 pc, and <105 pc. Our results strongly suggest that the polarized synchrotron emission toward the North Polar Spur at b > 30° is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement toward part of Loop IV (180 ± 15 pc) and find evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

Integrating radar stratigraphy with high resolution visible stratigraphy of the north polar layered deposits, Mars

Icarus ◽  
2013 ◽  
Vol 226 (2) ◽  
pp. 1241-1251 ◽  
Author(s):  
S. Christian ◽  
J.W. Holt ◽  
S. Byrne ◽  
K.E. Fishbaugh
Keyword(s):  
High Resolution ◽  
The North ◽  
North Polar ◽  
Polar Layered Deposits

scholarly journals The Observed Characteristics of the Local Magnetic Field

1974 ◽  
Vol 60 ◽  
pp. 137-150 ◽  
Author(s):  
J. B. Whiteoak
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Galactic Plane ◽  
Background Radiation ◽  
Field Structure ◽  
Local Magnetic Field ◽  
Field Parallel ◽  
Scale Field ◽  
Large Scale Field ◽  
Galactic Background

The main investigations of the local magnetic field are reviewed and are found to contain some conflict in interpretation. At radio wavelengths, studies have been made using both the Faraday rotation of the polarized radiation from extragalactic sources and pulsars, and the polarization of the galactic background radiation. With the former type of observation, although more data are available for extragalactic sources, any interpretation may be complicated by the influence of distant field structure. The results are consistent with a large-scale field parallel to the galactic plane, with a field strength of about 2 µG, and which is directed towards l=90°. This field contains irregularities in direction and strength on a scale of about 100–200 pc. The polarization of galactic background radiation may yield the most detailed information about the local field structure – the results to date show loops of magnetic fields extending along the radio spurs.The interpretation in terms of small-scale irregularities embedded in a large-scale field parallel to the galactic plane differs from that proposed to explain the optical polarization of starlight, in which a helical field configuration near the Sun was preferred to a more disordered pattern.

scholarly journals Stratigraphy of the north polar layered deposits of Mars from high-resolution topography

2016 ◽  
Vol 121 (8) ◽  
pp. 1445-1471 ◽  
Author(s):  
Patricio Becerra ◽  
Shane Byrne ◽  
Michael M. Sori ◽  
Sarah Sutton ◽  
Kenneth E. Herkenhoff
Keyword(s):  
High Resolution ◽  
The North ◽  
North Polar ◽  
Polar Layered Deposits

scholarly journals FARADAY TOMOGRAPHY OF THE NORTH POLAR SPUR: CONSTRAINTS ON THE DISTANCE TO THE SPUR AND ON THE MAGNETIC FIELD OF THE GALAXY

2015 ◽  
Vol 811 (1) ◽  
pp. 40 ◽  
Author(s):  
X. H. Sun ◽  
T. L. Landecker ◽  
B. M. Gaensler ◽  
E. Carretti ◽  
W. Reich ◽  
...  
Keyword(s):  
Magnetic Field ◽  
The North ◽  
The Galaxy ◽  
North Polar ◽  
The Magnetic Field

HRSC 3D Image products of the North Polar Layered Terrain of Mars

2020 ◽  
Author(s):  
Alfiah Rizky Diana Putri ◽  
Yu Tao ◽  
Jan-Peter Muller
Keyword(s):  
High Resolution ◽  
Digital Terrain Model ◽  
Space Science ◽  
Laser Altimeter ◽  
Mars Express ◽  
Stereo Camera ◽  
Terrain Model ◽  
The North ◽  
Digital Terrain ◽  
North Polar

&lt;p&gt;The NASA Mars Orbital Laser Altimeter (MOLA) Digital Terrain Model (DTM) has the greatest coverage available for Mars with an average resolution of&amp;#160;463 m/pixel (128pixel/ degree) globally and 112 m/ pixel (512 pixels/degree) for the polar regions [1]. The ESA Mars Express High-Resolution Stereo Camera (HRSC) is currently orbiting Mars and continuously mapping the surface, 98% with&amp;#160;resolutions finer than 100 m/pixel, and 100% at lower resolutions [2]. Previously,&amp;#160;50m/pixel DTMs were produced&amp;#160;using a NASA-VICAR-based pipeline developed by the German Aerospace Centre, with modifications from Kim and Muller [3] for the south polar region, using an image matcher based on the Gruen-Otto-Chau (Gotcha) algorithm [4].&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;In this research, we demonstrate application of the same method to the North Polar [5] region. Forty single strip DTMs have been processed and corrected to produce a north polar HRSC DTM mosaic at 50m/pixel. The assessment of the dataset to MOLA will be discussed. Moreover, a large number (~50) of the North polar HRSC images are co-registered and orthorectified using the DTM mosaic. We also demonstrate observations of the seasonal ice cap growth and retreat using the orthorectified images for Martian Year (MY) 27-32. In addition, the results for MY28-31 are compared against the observations from the Mars Colour Imager (MARCI)[6].&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;br&gt;ACKNOWLEDGEMENT:&amp;#160;Part of the research leading to these results has received partial funding from the European Union&amp;#8217;s Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n &amp;#778;&amp;#160;607379; The first author is supported by the Indonesian Endowment Fund for Education. We would also like to express gratitude to the HRSC team and the MOLA team for the usage of HRSC and MOLA data, and&amp;#160;Alexander Dumke for the exterior orientation processing results used within this research.&lt;br&gt;&lt;br&gt;[1] Smith, David, et al. 2001. &amp;#8220;Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars.&amp;#8221; Journal of Geophysical Research: Planets 106(E10):23689&amp;#8211;23722&lt;br&gt;&lt;br&gt;[2] Gwinner, et al. 2016. &amp;#8220;The High Resolution Stereo Camera (HRSC) of Mars Express and Its Approach to Science Analysis and Mapping for Mars and Its Satellites.&amp;#8221; Planetary and Space Science 126:93&amp;#8211;138&lt;br&gt;&lt;br&gt;[3] Kim and J-P. Muller, 2009. &amp;#8220;Multi-resolution topographic data extraction from Martian stereo imagery.&amp;#8221; Planetary and Space Science, 57(14-15):2095-2112.&lt;br&gt;&lt;br&gt;[4] D. Shin and J-P. Muller, 2012. &amp;#8220;Progressively weighted adaptive correlation matching for quasi-dense 3d reconstruction.&amp;#8221; Pattern Recognition, 45(10):3795-3809.&lt;br&gt;&lt;br&gt;[5] Putri, A.R.D., et al., 2019. &amp;#8220;A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express.&amp;#8221; Planetary and Space Science.&lt;br&gt;&lt;br&gt;[6] Calvin, W.M., et al., 2015. &amp;#8220;Interannual and seasonal changes in the north polar ice deposits of Mars: Observations from MY 29&amp;#8211;31 using MARCI.&amp;#8221; Icarus, 251, pp.181-190.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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