scholarly journals High-latitude dust clouds LDN 183 and LDN 169: distances and extinctions

2018 ◽  
Vol 611 ◽  
pp. A9 ◽  
Author(s):  
V. Straižys ◽  
R. P. Boyle ◽  
J. Zdanavičius ◽  
R. Janusz ◽  
C. J. Corbally ◽  
...  
Keyword(s):  
High Latitude ◽  
Molecular Clouds ◽  
Interstellar Extinction ◽  
Two Dimensional ◽  
Front Edge ◽  
Dust Layer ◽  
Dust Clouds ◽  
Color System ◽  
Data Release ◽  
Trigonometric Parallaxes

Interstellar extinction is investigated in a 2°× 2° area containing the dust and molecular clouds LDN 183 (MBM 37) and LDN 169, which are located at RA = 15h 54m, Dec = − 3°. The study is based on a photometric classification in spectral and luminosity classes of 782 stars selected from the catalogs of 1299 stars down to V = 20 mag observed in the Vilnius seven-color system. For control, the MK types for the 18 brightest stars with V between 8.5 and 12.8 mag were determined spectroscopically. For 14 stars, located closer than 200 pc, distances were calculated from trigonometric parallaxes taken from the Gaia Data Release 1. For about 70% of the observed stars, two-dimensional spectral types, interstellar extinctions AV, and distances were determined. Using 57 stars closer than 200 pc, we estimate that the front edge of the clouds begins at 105 ± 8 pc. The extinction layer in the vicinities of the clouds can be about 20 pc thick. In the outer parts of the clouds and between the clouds, the extinction is 0.5–2.0 mag. Behind the Serpens/Libra clouds, the extinction range does not increase; this means that the dust layer at 105 pc is a single extinction source.

scholarly journals HIGH-LATITUDE, TRANSLUSCENT MOLECULAR CLOUDS AS PROBES OF LOCAL COSMIC RAYS

2015 ◽  
Vol 805 (1) ◽  
pp. 50 ◽  
Author(s):  
Ryan D. Abrahams ◽  
Timothy A. D. Paglione
Keyword(s):  
Cosmic Rays ◽  
High Latitude ◽  
Molecular Clouds

scholarly journals CO and OH in the Galactic Center Region

1980 ◽  
Vol 87 ◽  
pp. 111-112
Author(s):  
Junji Inatani ◽  
Nobuharu Ukita
Keyword(s):  
Emission Line ◽  
Intensity Ratio ◽  
Molecular Clouds ◽  
Galactic Center ◽  
Point Of View ◽  
The Other ◽  
Kinetic Temperature ◽  
Two Dimensional ◽  
Center Region ◽  
Dimensional Distribution

The two-dimensional distribution of molecular clouds in the galactic center region has been investigated in the CO 115 GHz line and in the OH 1665 and 1667 MHz lines. As the former is an emission line, we can find molecular clouds without the unavoidable bias to continuum sources which is inherent in a survey of OH absorption lines. Because the CO line is usually optically thick, the brightness temperature of the line is directly related to the kinetic temperature of the cloud. On the other hand, the real optical depth of the OH line can be obtained from the intensity ratio between 1665 and 1667 MHz lines (assuming LTE). From this point of view we have compared the CO and OH observational results.

scholarly journals Wave-Breaking Characteristics of Northern Hemisphere Winter Blocking: A Two-Dimensional Approach

2013 ◽  
Vol 26 (13) ◽  
pp. 4535-4549 ◽  
Author(s):  
Giacomo Masato ◽  
Brian J. Hoskins ◽  
Tim Woollings
Keyword(s):  
High Latitude ◽  
Wave Breaking ◽  
Potential Temperature ◽  
Regional Analysis ◽  
Jet Stream ◽  
Two Dimensional ◽  
Horizontal Shear ◽  
Cluster Technique ◽  
Meridional Gradient ◽  
The Pacific

Abstract This paper generalizes and applies recently developed blocking diagnostics in a two-dimensional (2D) latitude–longitude context, which takes into consideration both mid- and high-latitude blocking. These diagnostics identify characteristics of the associated wave breaking as seen in the potential temperature θ on the dynamical tropopause, particularly the cyclonic or anticyclonic direction of wave breaking (“DB index”) and the relative intensity (“RI index”) of the air masses that contribute to blocking formation. The methodology is extended to a 2D domain and a cluster technique is deployed to classify mid- and high-latitude blocking according to the wave-breaking characteristics. Midlatitude blocking is observed over Europe and Asia, where the meridional gradient of θ is generally weak, whereas high-latitude blocking is mainly present over the oceans, to the north of the jet stream, where the meridional gradient of θ is much stronger. They occur on the equatorward and poleward flank of the jet stream, respectively, where the horizontal shear ∂u/∂y is positive in the first case and negative in the second case. A regional analysis is also conducted. Warm-cyclonic blocking over the Pacific and cold-anticyclonic blocking over Europe are identified as the most persistent types and are associated with large amplitude anomalies in temperature and precipitation. Finally, the high-latitude cyclonic events seem to correlate well with low-frequency modes of variability over the Pacific and Atlantic Oceans.

Molecular abundances in the high-latitude molecular clouds

1988 ◽  
Vol 326 ◽  
pp. 909 ◽  
Author(s):  
Loris Magnani ◽  
Leo Blitz ◽  
Jan G. A. Wouterloot
Keyword(s):  
High Latitude ◽  
Molecular Clouds ◽  
Molecular Abundances

Dense gas in high-latitude molecular clouds

1995 ◽  
Vol 441 ◽  
pp. 244 ◽  
Author(s):  
William T. Reach ◽  
Marc W. Pound ◽  
David J. Wilner ◽  
Youngung Lee
Keyword(s):  
High Latitude ◽  
Molecular Clouds ◽  
Dense Gas

Infrared cirrus and high-latitude molecular clouds

1986 ◽  
Vol 306 ◽  
pp. L101 ◽  
Author(s):  
Janet L. Weiland ◽  
Leo Blitz ◽  
Eli Dwek ◽  
M. G. Hauser ◽  
Loris Magnani ◽  
...  
Keyword(s):  
High Latitude ◽  
Molecular Clouds

scholarly journals Two-Dimensional Radiation-Hydrodynamics Calculations of the Formation of 0-B Associations in Dense Molecular Clouds

1980 ◽  
Vol 58 ◽  
pp. 275-282
Author(s):  
Richard I. Klein ◽  
Maxwell T. Sandford II ◽  
Rodney W. Whitaker
Keyword(s):  
Star Formation ◽  
Formation Process ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Radiation Hydrodynamics ◽  
Combined Effects ◽  
Two Dimensional ◽  
Density Enhancement

AbstractTwo-dimensional calculations of ionization-shockwave propagation into a curved molecular cloud are presented. Density enhancement occurs due to the combined effects of cloud curvature and radiation flow. The star formation process is expected to be enhanced near the edges of irregularly shaped molecular clouds.

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