scholarly journals Fitting procedure for estimating interstellar extinction at high galactic latitudes

2021 ◽  
Vol 30 (1) ◽  
pp. 168-175
Author(s):  
Aleksandra Avdeeva ◽  
Dana Kovaleva ◽  
Oleg Malkov ◽  
Alexey Nekrasov
Keyword(s):  
Spherical Harmonics ◽  
High Latitude ◽  
Mathematical Description ◽  
Spectroscopic Data ◽  
Interstellar Extinction ◽  
The Sun ◽  
Fitting Procedure ◽  
Visual Extinction

Abstract We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey. We approximate the results with the cosecant law in each area thus deriving the parameters of the barometric formula for different lines of sight. The distribution of the parameters over the entire sky is described using spherical harmonics. As a result, we get a mathematical description of the interstellar visual extinction for different lines of sight and distances from the Sun which can be used for estimating interstellar extinction.

Galactic Infrared Astronomy

1971 ◽  
Vol 2 (1) ◽  
pp. 14-20 ◽  
Author(s):  
A. R. Hyland
Keyword(s):  
Interstellar Extinction ◽  
Infrared Astronomy ◽  
The Sun ◽  
Late Type ◽  
Infrared Observations ◽  
Effective Temperatures

Until the last six years few infrared observations of astronomical objects (other than the Sun and planets) had been attempted. Those few were primarily concerned with obtaining bolometric corrections and effective temperatures, the variation of bolometric magnitudes of late-type variables, and the derivation of the laws of interstellar extinction.

Diurnal cosmic-ray variation with the inclusion of the geometrical effects and the asymptotic cones of approach

1968 ◽  
Vol 46 (10) ◽  
pp. S809-S811 ◽  
Author(s):  
L. I. Dorman ◽  
S. Fischer
Keyword(s):  
Spatial Distribution ◽  
High Latitude ◽  
Intensity Variation ◽  
Cosmic Ray ◽  
The Sun ◽  
Neutron Monitors ◽  
Asymptotic Cones ◽  
Diurnal Anisotropy ◽  
Geometrical Effects

Employing the data from cosmic-ray neutron monitors at high latitude, the spatial distribution of the axis of the diurnal anisotropy is determined. The effects of the earth's revolution around the sun on the diurnal intensity variation is investigated. A new method for further investigation of the spatial distribution of the anisotropy and for the determination of its spectra in various directions has been proposed.

scholarly journals Optical Observations of Galactic and Extragalactic Light: Implications for Galactic Structure

1990 ◽  
Vol 139 ◽  
pp. 21-34
Author(s):  
Gary N. Toller
Keyword(s):  
Galactic Plane ◽  
Historical Review ◽  
Interstellar Extinction ◽  
Galactic Structure ◽  
Optical Observations ◽  
The Sun ◽  
Color Distribution ◽  
Background Light ◽  
Dominant Component ◽  
Spiral Arm

A historical review of integrated starlight, diffuse galactic light, and extragalactic light studies is presented. Together, these components compose the “background light.” Methods ranging from star counts to space-based photometric surveys have succeeded in quantifying the contribution of each component of the background. Integrated starlight is the dominant component. The contribution of diffuse galactic light in the general interstellar medium peaks slightly off the galactic plane and declines toward higher latitudes. The extragalactic light has been determined from both galaxy counts and photometric methods. The blue and red intensity and B–R color distribution of background light have been mapped. The relation between galactic structure and background light measurements is established. The distribution of interstellar extinction is the primary regulator of the brightness. However, spiral arm and stellar distribution effects are discerned in Carina and Sagittarius. The sun lies 13 pc north of the galactic plane as defined by brightness and dust distributions.

scholarly journals Interstellar extinction from photometric surveys: application to four high-latitude areas

2018 ◽  
Vol 27 (1) ◽  
pp. 62-69 ◽  
Author(s):  
Oleg Malkov ◽  
Sergey Karpov ◽  
Elena Kilpio ◽  
Sergey Sichevsky ◽  
Dmitry Chulkov ◽  
...  
Keyword(s):  
High Latitude ◽  
Interstellar Extinction ◽  
Virtual Observatory ◽  
Multicolor Photometry

Abstract Information on interstellar extinction and dust properties may be obtained from modern large photometric surveys data. Virtual Observatory facilities allow users to make a fast and correct cross-identification of objects from various surveys. It yields a multicolor photometry data on detected objects and makes it possible to estimate stellar parameters and calculate interstellar extinction. A 3D extinction map then can be constructed. The method was applied to 2MASS, SDSS, GALEX and UKIDSS surveys. Results for several high-latitude areas are obtained, compared with independent sources and discussed here.

scholarly journals Introduction

1995 ◽  
Vol 10 ◽  
pp. 319-320
Author(s):  
W. Däppen
Keyword(s):  
Spherical Harmonics ◽  
Solar Rotation ◽  
Solar Neutrinos ◽  
The Sun ◽  
Solar Oscillations ◽  
Good Information ◽  
Solar Neutrino Problem ◽  
Oscillation Frequencies ◽  
Very High ◽  
Better Than

Since the early 1960s the surface of the Sun has been know to be in a regular pulsating motion with periods of about 5 minutes. While at the beginning various explanations were offered, only in the 1970s it was recognized that these so-called solar oscillations are manifestations of global motions of the Sun about its equilibrium. Helioseismology is the name of the branch of astrophysics that deals with deciphering these data, that cover the whole range of spherical harmonics from l = 0 (radial) to very high angular order (above l = 1000). Thanks to observational data of superb quality (each of the oscillation frequencies is measured accurately to better than one part in ten thousand), our knowledge of the Sun has leap-frogged in the last 20 years. For instance, we now know the run of temperature inside the Sun, or have good information about the internal solar rotation. In the solar neutrino problem the data from solar oscillations have become a compulsory testing stone for any model proposed to explain the discrepancy between observed and theoretically predicted solar neutrinos.

scholarly journals Airglow and Aurorae from Dome A, Antarctica

2012 ◽  
Vol 8 (S288) ◽  
pp. 302-303
Author(s):  
Geoff Sims ◽  
Michael C. B. Ashley ◽  
Xiangqun Cui ◽  
Jon R. Everett ◽  
LongLong Feng ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Spectroscopic Data ◽  
Optical Observations ◽  
Zenith Distance ◽  
Light Pollution ◽  
Artificial Light ◽  
The Sun ◽  
Dome A ◽  
Near Ir ◽  
Nm Range

AbstractDespite the absence of artificial light pollution at Antarctic plateau sites such as Dome A, other factors such as airglow, aurorae and extended periods of twilight have the potential to adversely affect optical observations. We present a statistical analysis of the airglow and aurorae at Dome A using spectroscopic data from Nigel, an optical/near-IR spectrometer operating in the 300–850 nm range. The median auroral contribution to the B, V and R photometric bands is found to be 22.9, 23.4 and 23.0 mag arcsec−2 respectively. We are also able to quantify the amount of annual dark time available as a function of wavelength; on average twilight ends when the Sun reaches a zenith distance of 102.6°.

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.

Study of starspots in fully convective stars using three dimensional MHD simulations

2018 ◽  
Vol 13 (S340) ◽  
pp. 303-304
Author(s):  
Arnab Basak ◽  
Dibyendu Nandy
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
High Latitude ◽  
Three Dimensional ◽  
Stellar Dynamics ◽  
The Sun ◽  
Dynamo Action ◽  
Magnetic Structures ◽  
Mhd Simulations ◽  
Self Consistent

AbstractConcentrated magnetic structures such as sunspots and starspots play a fundamental role in driving solar and stellar activity. However, as opposed to the sun, observations as well as numerical simulations have shown that stellar spots are usually formed as high-latitude patches extended over wide areas. Using a fully spectral magnetohydrodynamic (MHD) code, we simulate polar starspots produced by self-consistent dynamo action in rapidly rotating convective shells. We carry out high resolution simulations and investigate various properties related to stellar dynamics which lead to starspot formation.

scholarly journals The Problem of the UV Interstellar Absorption Band at 2200A

1977 ◽  
Vol 43 ◽  
pp. 26-26
Author(s):  
D.J. Carnochan ◽  
K. Nandy ◽  
A.J. Willis ◽  
R. Wilson
Keyword(s):  
Galactic Plane ◽  
Interstellar Extinction ◽  
Extinction Curve ◽  
Absorption Feature ◽  
The Sun ◽  
The Galaxy ◽  
Satellite Experiment ◽  
Using Data ◽  
Broad Scale ◽  
Pronounced Peak

The ultraviolet interstellar extinction curve from 2740Å to 1350Å has been obtained using data from the S2/68 satellite experiment. The extinction increases into the ultraviolet and shows a pronounced peak at 2200Å. This is interpreted as a general scattering continuum with a strong absorption feature superposed on it at 2200Å. The profile of the feature appears to be symmetrical and has a half-width of 360Å. There is a strong correlation between the strength of the feature and the scattering part of the curve in both the ultraviolet and the visible. On a broad scale the shape of the extinction curve is constant showing no variation with distance from the sun, direction around the galaxy, and height above the galactic plane.

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