CDS

2015A&A...584A.108S

Query : 2015A&A...584A.108S

2015A&A...584A.108S - Astronomy and Astrophysics, volume 584A, 108-108 (2015/12-1)

Extinction and dust properties in a clumpy medium.

SCICLUNA P. and SIEBENMORGEN R.

Abstract (from CDS):

The dust content of the universe is primarily explored via its interaction with stellar photons, which are absorbed or scattered by the dust, producing the effect known as interstellar extinction. However, owing to the physical extension of the observing beam, real observations may detect a significant number of dust-scattered photons. This may result in a change in the observed (or effective) extinction with a dependence on the spatial distribution of the dust and the spatial resolution of the instrument. We investigate the influence of clumpy dust distributions on the effective extinction toward both embedded sources and those seen through the diffuse interstellar medium (ISM). We use a Monte Carlo radiative transfer code to examine the effective extinction for various geometries. By varying the number, optical depth and volume-filling factor of clumps inside the model for spherical shells and the diffuse interstellar medium (ISM), we explore the evolution of the extinction curve and effective optical depth. Depending on the number of scattering events in the beam, the extinction curve is observed to steepen in homogeneous media and flatten in clumpy media. As a result, clumpy dust distributions are able to reproduce extinction curves with arbitrary RV,eff, the effective ratio of total-to-selective extinction. The flattening is also able to ``wash out'' the 2175Å bump and results in a shift of the peak to shorter wavelengths. The mean RV,eff of a shell is shown to correlate with the optical depth of an individual clump and the wavelength at which a clump becomes optically thick. Similar behaviour is seen for edge-on discs or tori. However, at grazing inclinations the combination of extinction and strong forward scattering results in chaotic behaviour. Caution is therefore advised when attempting to measure extinction in AGN tori for example or toward SNIa or GRB afterglows. In face-on discs, the shape of the scattered continuum is observed to change significantly with clumpiness, however, unlike absorption features, individual features in the scattering cross-sections are preserved. Finally, we show that diffuse interstellar extinction is not significantly modified by scattering on distance scales of a few kpc.

Abstract Copyright: ∼

Journal keyword(s): radiative transfer - dust, extinction - circumstellar matter - ISM: structure - scattering

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021 		#notes
1 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2557 0

Query : 2015A&A...584A.108S

Basic data :
* alf Lyr -- Variable Star of delta Sct type
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		* (*,AG,...), IR (AKARI,IRAS,...), ** (ADS,CCDM,...), PM* (LSPM,LTT,...), V* (CSV,NSV,...), UV (CEL,EUVE,...), smm (JCMTSE,JCMTSF), dS* (2003AstL), X (1E)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		18 36 56.33635 +38 47 01.2802 (Optical) [ 3.51 2.81 90 ] A 2007A&A...474..653V
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		18 35 14.66713 +38 44 09.8049 [ 3.51 2.81 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		067.44820813 +19.23725227 [ 3.51 2.81 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		200.94 286.23 [0.32 0.40 0] A 2007A&A...474..653V
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) -20.60 [0.2] / z(~) -0.000069 [0.000001] / cz -20.60 [0.20]
   A 2006AstL...32..759G
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		130.23 [0.36] A 2007A&A...474..653V
Spectral type is made of 3 parts: %coding is composed of 4 parts :
  • the spectral type, which is made of a temperature class, eventually a luminosity class (roman number) and/or spectral peculiarities;
  • a quality letter: A=best quality→E=worst quality, {� } =unknown quality %
  • a quality letter: A=best quality -> E=worst quality, {� } =unknown quality
  • bibcode : bibcode of the spectral type reference
Spectral type: 		A0Va C 2003AJ....126.2048G
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (8) :
U 0.03 [~] C 2002yCat.2237....0D
B 0.03 [~] C 2002yCat.2237....0D
V 0.03 [~] C 2002yCat.2237....0D
R 0.07 [~] C 2002yCat.2237....0D
I 0.10 [~] C 2002yCat.2237....0D
J -0.177 [0.206] D 2003yCat.2246....0C
H -0.029 [0.146] D 2003yCat.2246....0C
K 0.129 [0.186] D 2003yCat.2246....0C
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR.
The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!). sed-help-icon

Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

: 1 : 61 Display criteria :

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (63) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

* alf Lyr GCRV 11085 LSPM J1836+3847 TD1 22883
* 3 Lyr GEN# +1.00172167 LTT 15486 TIC 157587146
ADS 11510 A GJ 721 2MASS J18365633+3847012 TYC 3105-2070-1
AG+38 1711 GJ 721.0 N30 4138 UBV 15842
AKARI-IRC-V1 J1836564+384703 HD 172167 NAME Vega UBV M 23118
ASCC 507896 HGAM 706 NLTT 46746 USNO-B1.0 1287-00305764
BD+38 3238 HIC 91262 NSV 11128 USNO 882
CCDM J18369+3847A HIP 91262 8pc 128.93 uvby98 100172167
CEL 4636 HR 7001 PLX 4293 V* alf Lyr
CSI+38 3238 1 IDS 18336+3841 A PLX 4293.00 WDS J18369+3846A
CSV 101745 IRAS 18352+3844 PMC 90-93 496 WEB 15681
1E 183515+3844.3 IRAS F18352+3844 PPM 81558 WISE J183656.49+384703.9
EUVE J1836+38.7 IRC +40322 RAFGL 2208 Zkh 277
FK5 699 JCMTSE J183656.4+384709 ROT 2633 [HFE83] 1223
GAT 1285 JCMTSF J183656.4+384709 SAO 67174 EQ 183456.7+384615.4
GC 25466 JP11 2999 SKY# 34103

References (2557 between 1850 and 2021) (Total 2557)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 20    diameter : 1    ROT : 6    Fe_H : 49    PLX : 4    PM : 6    MK : 35   

   

Observing logs


herschel : 10    ISO : 99    IUE : 65   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : * alf Lyr

Search by coordinates in Vizier (radius: 7 arcsec)

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2021.10.20-00:49:05

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