Double Stars with Common Proper Motion

1965 ◽  
Vol 5 ◽  
pp. 49-51
Author(s):  
Willem J. Luyten
Keyword(s):  
Proper Motion ◽  
Galactic Latitude ◽  
Schmidt Telescope ◽  
Polar Cap ◽  
Double Stars ◽  
The North ◽  
North Polar

The proper Motion Survey with the 48-in Schmidt telescope has now progressed far enough such that we may begin to make some meaningful statistical discussions of the results obtained. Altogether 135 regions have been blinked – one seventh of the total -and in particular all fifty plates covering the area of the North Polar Cap, north of declination +69 (1855) have been blinked and completely measured. This area covers 1360 square degrees, almost exactly one thirtieth of the entire sphere, and, since the galactic latitude of the Pole is 27°, and its distance from the ‘average’ solar apex is about 55° this region may be considered as not too unrepresentative for the whole sky.

scholarly journals Double Stars with Common Proper Motion

1971 ◽  
Vol 5 ◽  
pp. 49-51
Author(s):  
Willem J. Luyten
Keyword(s):  
Proper Motion ◽  
Schmidt Telescope ◽  
Polar Cap ◽  
Double Stars ◽  
The North ◽  
North Polar

The proper Motion Survey with the 48-in Schmidt telescope has now progressed far enough such that we may begin to make some meaningful statistical discussions of the results obtained. Altogether 135 regions have been blinked - one seventh of the total - and in particular all fifty plates covering the area of the North Polar Cap, north of declination +69 (1855) have been blinked and completely measured.

scholarly journals Avalanches of the martian north polar cap

2020 ◽  
Author(s):  
Patricio Becerra ◽  
Susan Conway ◽  
Nicholas Thomas ◽  
Keyword(s):  
Polar Regions ◽  
Martian Surface ◽  
Polar Cap ◽  
Water Ice ◽  
The North ◽  
Imaging Science ◽  
Resolution Imaging ◽  
North Polar ◽  
Gas Expansion ◽  
Trigger Mechanisms

<p>In 2008, the High Resolution Imaging Science Experiment (HiRISE) on board NASA’s MRO fortuitously captured several discrete clouds of material in the process of cascading down a steep scarp of the water-ice-rich north polar layered deposits (NPLD). The events were only seen during a period of ~4 weeks, near the onset of martian northern spring in 2008, when the seasonal cover of CO2 is beginning to sublimate from the north polar regions. Russell et al. [1] analyzed the morphology of the clouds, inferring that the particles involved were mechanically analogous to terrestrial “dry, loose snow or dust”, so that the events were similar to terrestrial “powder avalanches” [2]. HiRISE confirmed the seasonality of avalanche occurrence the following spring, and continued to capture between 30 and 50 avalanches per season (fig. 1b,c) between 2008 and 2019, for a total of 7 Mars Years (MY29–MY35) of continuous scarp monitoring.</p><p>In this work we will present statistics on these events, in an attempt to quantify their effect on the mass balance of the NPLD, and with respect to competing processes such as viscous deformation and stress-induced block falls that do not trigger avalanches [3,4]. We also use a 1D thermal model [5] to investigate the sources and trigger mechanisms of these events. The model tracks the accumulation and ablation of seasonal CO2 frost on a martian surface. Russell et al. [1] support an initiation through gas-expansion related to the presence of CO2 frost on the scarp. Therefore the amount of frost that lingers on different sections of the model scarp at the observed time of the avalanches will provide evidence either for or against this particular mechanism. We will present preliminary results and discuss their implications.</p><p>References: [1] P. Russell et al. (2008) Geophys. Res. Lett. 35, L23204. [2] D. McClung, P.A. Schaerer (2006), Mountaineers, Seattle Wash. [3] Sori, M. M., et al., Geophys. Res. Lett., 43. [4] Byrne et al. (2016), 6th Int. Conf. Mars Polar Sci. Exploration [4] C. M. Dundas and S. Byrne (2010) Icarus 206, 716.</p>

scholarly journals Variations of the martian CO2 abundance with Martian season

1971 ◽  
Vol 40 ◽  
pp. 196-202
Author(s):  
Edwin S. Barker
Keyword(s):  
Growth Parameters ◽  
Polar Cap ◽  
Preliminary Results ◽  
Regression Curves ◽  
The North ◽  
Partial Pressures ◽  
North Polar

All previous published equivalent widths of the Martian CO2 bands including the 1967 apparition coverage at McDonald Observatory are reduced to CO2 abundances using the same curve of growth parameters. The corresponding CO2 partial pressures (assuming a pure CO2 atmosphere), along with the regression curves of the north polar cap, are presented as functions of Martian heliocentric longitudes, Ls. A correlation is noted between the maximum CO2 abundance and minimum north cap diameter and the decrease in CO2 abundance when the northern polar haze begins to reform. Preliminary results of the 1969 apparition coverage at McDonald Observatory are also presented.

scholarly journals NPC, A New Combined Position Catalogue of Stars in the Northern Pole Region

1997 ◽  
Vol 165 ◽  
pp. 499-504
Author(s):  
L.G. Taff ◽  
V.V. Tel’nyuk-Adamchuk ◽  
O.A. Molotaj
Keyword(s):  
Main Task ◽  
Proper Motions ◽  
Polar Cap ◽  
Position Errors ◽  
The North ◽  
The Mean ◽  
North Polar ◽  
Right Ascension ◽  
Second Use ◽  
Rms Errors

AbstractThe main task of this work was to construct a new catalogue of positions and proper motions of stars in the north polar cap, and using the results obtained to study the systematic features of the source catalogues as well as the reference system in the polar region. To achieve the goal, thirteen source catalogues, both meridian and photographic, covering an epoch span near one and a half century, were collected. Most of them were not involved in the process of both the PPM and the ACRS constructions. The new combined catalogue of positions and proper motions, named North Polar Catalogue (NPC), lists 4272 stars on the FK5 system, J2000.0. The catalogue was constructed using the method of infinitely overlapping circles. It represents the second use of this procedure to construct a star catalogue. External rms accuracy of positions for the epoch of 2000 is equal to 015 and 025 for the centennial proper motions, respectively. The internal rms errors of positions at the mean catalogue epoch, near 1940, are equal to 018 and 015 for right ascension and declination correspondingly, while external rms position errors for that epoch are of the order of 005. Comparisons were made between the NPC and three modern catalogues, the FK5, PPM, and ACRS. The systematic differences between the new catalogue and PPM one for the epoch of 2000 are valuable, especially in the case of errors depending on right ascension. The authors consider as an essential part of the systematic differences that, which is caused by some shortcomings of the PPM in the polar zone. For the mean epoch of the new catalogue positions the systematic differences are smaller.

scholarly journals Martian polar and circum-polar sulfate-bearing deposits: Sublimation tills derived from the North Polar Cap

Icarus ◽  
2010 ◽  
Vol 209 (2) ◽  
pp. 434-451 ◽  
Author(s):  
M. Massé ◽  
O. Bourgeois ◽  
S. Le Mouélic ◽  
C. Verpoorter ◽  
L. Le Deit ◽  
...  
Keyword(s):  
Polar Cap ◽  
The North ◽  
North Polar

scholarly journals The Space Density of M Dwarfs - An Observational Program

1977 ◽  
Vol 4 (2) ◽  
pp. 29-30
Author(s):  
Peter Pesch
Keyword(s):  
Proper Motion ◽  
Wavelength Region ◽  
Schmidt Telescope ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Space Density ◽  
The North ◽  
Cool Stars ◽  
Objective Prism ◽  
North Galactic

In spite of extensive proper motion surveys, there remains some uncertainty about the space density and the kinematics of late-type dwarf stars. This uncertainty is primarily due to the unknown kinematic bias introduced by the proper motion discovery technique.A spectrographic search, especially one using an objective prism on a Schmidt telescope, can identify significant numbers of intrinsically (and actually) faint stars, free from any kinematic bias. To find faint and cool stars, one chooses an objective prism with low dispersion and emulsions sensitive to the red and near photographic infrared. At low dispersions, in this wavelength region, there are no reliable luminosity criteria. Thus Sanduleak conducted his survey in the direction of the north galactic pole, with the expectation that very few remote giants would contaminate his results. A catalog of 273 probable dwarf stars of type M3 and later (Sanduleak, N. 1976, A.J., 81, 350) based on his objective prism survey in the direction of the north galactic pole is now available. Thanks to W.J. Luyten (1976, Proper Motion Survey with the Forty-Eight Inch Schmidt Telescope XLVI (Univ. Minnesota, Minneapolis)) proper motions have been measured for all of these stars.

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