scholarly journals A study of far infrared loop at -5o galactic latitude around pulsar J1627-5547

BIBECHANA ◽  
2017 ◽  
Vol 15 ◽  
pp. 70-78
Author(s):  
A K Jha ◽  
B Aryal
Keyword(s):  
Outer Region ◽  
Far Infrared ◽  
Core Region ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Distribution Maps ◽  
The Core ◽  
The Past ◽  
Dust Mass ◽  
Region Size

We present physical properties of the core region of infrared loop G329-05 which is found to be located within 1o from the pulsar PSR J1627-5547.  The loop has 3-fold reduced flux density than its surroundings.  In the 100 micron infrared map, a new cavity-like isolated far infrared dust structure of core region (size ~0.750 x 0.230 ) is  found at R.A. (J2000)= 16h 27m 19.9s & Dec. (J2000) = -56035’14”. This loop is believed to be formed because of high pressure events occurred in the past. The dust color temperature of the core region is found to lie in the range 25.26 ± 0.09 K to 27.91 ± 0.09 K, whereas the value of dust color temperature increased to 36.72 ± 0.18  K for the outer region. The dust color temperature and dust mass distribution maps showed that the low temperature region has greater density as expected. The dust mass of the core region of the loop is found to be 1.67 x 1027 kg i.e. about 0.00835 Mʘ. The core region of the loop is found to be edge-on (i ˃780) whereas the larger structure is faced-on (i =00). Possible explanation of results will be presented.BIBECHANA 15 (2018) 70-76

scholarly journals A Study of Far Infrared Cavity At -3.6° Galactic Latitude

2019 ◽  
Vol 5 (1) ◽  
pp. 54-58
Author(s):  
B. B. Sapkota ◽  
B. Aryal
Keyword(s):  
High Pressure ◽  
Inclination Angle ◽  
White Dwarf ◽  
Far Infrared ◽  
Core Region ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Dust Mass

We have present properties like inclination angle, dust color temperature and dust mass of core region in far infrared located nearby White dwarf WD2236+541.The size of cavity is 0.84 pc×0.51 pc. The cavity is formed by high pressure at the time of white dwarf formation. The dust color temperature varies from 22.42K to 27.43 K. The inclination angle of cavity is 54.2°. The position of white dwarf is found at R.A. J (2000)= 22h38m24s and Dec. J (2000)= +54°26m19s.

scholarly journals Study Of A Far Infrared Cavity At The Galactic Plane

2021 ◽  
Vol 14 (14) ◽  
pp. 68-74
Author(s):  
A. K. Gautam ◽  
B. Aryal
Keyword(s):  
High Pressure ◽  
Radiation Field ◽  
Galactic Plane ◽  
Local Thermodynamic Equilibrium ◽  
Far Infrared ◽  
Color Temperature ◽  
Galactic Latitude ◽  
The Past ◽  
Planck Function ◽  
Dust Mass

A far infrared dust cavity nearby AGB star namely AGB19+26 found to be located, centered at R.A.(J2000)= 20h 02m 02.8s and Dec.(J2000)= 26° 52' 36.8".Distribution of Planck function, dust color temperature, dust mass and visual extinction of the far infrared cavity was studied. This cavity was found to have following properties: (a) it is located nearby AGB star named AGB19+26around far infrared loopG064-01 at 2000 pc, (b) it is close to the Galactic plane at galactic latitude -1.2° therefore the radiation field is strong and (c) the diameter of the cavity is greater than 0.2° on IRAS. The dust color temperatures are found to be in the range 21.48 ± 0.25 K to 22.03 ± 0.12 K. Planck function was found to be non-uniform along its extension and compression, suggesting that the dust and grains are not in the local thermodynamic equilibrium, possibly because of external cause. It is therefore, a deviation from the Gaussian distribution is noted in the histogram of dust color temperature. It is concluded that the cavity was formed due to the high pressure events occurred in the past.

scholarly journals Study of a Far Infrared Cavity at 60 μm and 100 μm IRAS Map around the Carbon-Rich AGB Star at Galactic Latitude 8.6°

2020 ◽  
Vol 13 (13) ◽  
pp. 14-19
Author(s):  
A.K. Gautam ◽  
B. Aryal
Keyword(s):  
Flux Density ◽  
Far Infrared ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Planck Function ◽  
Visual Extinction ◽  
Dust Mass

In this paper, we discussed about the dusty environment of the far infrared cavity around the AGB star located at R.A. (J2000) =01h41m 01s and Dec (J2000) = 71° 04’ 00 9, lying within far infrared loop G125+09 6 in the far infrared IRAS maps. A cavity like structure (major diameter ∼2.55pc & minor diameter ∼0.77pc) is found to lie at R.A. (J2000) = 01h46m57.2s and DEC (J2000) = 71°24’57.1”, located at a distance ∼ 220pc from the star. We studied the distribution of flux density, dust color temperature, dust mass, visual extinction in the cavity. We further studied the distribution Planck function along extension and compression, distribution of dust color temperature along square of the major and minor diameters. The dust color temperature is found to lie in the range (19.7±1.25) K to (21.1±0.55)K which shows the cavity is isolated and stable. A possible explanation of the results will be discussed.

scholarly journals Study of a Far Infrared Cavity around an AGB Star under Iras Survey at Galactic Latitude -1.6°

2019 ◽  
Vol 5 (1) ◽  
pp. 35-41
Author(s):  
A. K. Gautam ◽  
B. Aryal
Keyword(s):  
Physical Properties ◽  
Flux Density ◽  
Far Infrared ◽  
Mean Free Path ◽  
Color Temperature ◽  
Dust Particles ◽  
Galactic Latitude ◽  
Contour Map ◽  
Dust Mass ◽  
Low Offset

In this paper, we discuss about the physical properties of the dusty environment around the AGB star located at R.A. (J2000) = 06h 42m 02s and Dec (J2000) = 00° 53’ 00”, in the far infrared (60 and 100μm) IRAS maps. A cavity like structure (major diameter ∼ 2.5 pc & minor diameter ∼0.9 pc) is found to lie at R.A. (J2000) = 06h 41m 43.03s and DEC (J2000) = 01° 09’ 22.8”, located at a distance ∼ 405 pc from the star. By using contour map diagram, we studied the distribution of flux density, dust color temperature, dust mass and outflow mass in the cavity. The dust color temperature is found to lie in the range 21.4K to 21.9 K which shows the cavity is isolated and independently evolved. Such a low offset temperature variation shows that the star is stable and its life is long. Dust particles are less interacting and mean free path is large. The cavity may be in thermally pulsating phase. Product of dust color temperature and visual extinction is found to be less than one. A possible explanation of the results will be discussed.

scholarly journals Dust Structure Nearby G229-03

2021 ◽  
Vol 5 (01) ◽  
pp. 2-7
Author(s):  
Hem Shrestha ◽  
Ajay Kumar Jha ◽  
Saroj Nepal ◽  
Aatmaram Tiwari ◽  
Kamana Bantawa ◽  
...  
Keyword(s):  
Inclination Angle ◽  
High Velocity ◽  
Outer Region ◽  
Far Infrared ◽  
Core Region ◽  
Average Temperature ◽  
The Core ◽  
Maximum Temperatures ◽  
Velocity Cloud ◽  
High Velocity Cloud

The Sky View Virtual Observatory was used for the systematic search of dust structures within the far-infrared loop G229-03. The source (object) responsible for the formation of the cavity of interest was detected by the Set of Identifications, Measurements, and Bibliography for Astronomical Data (SIMBAD) database. The total mass of the loop was 8.50031 × 1029 kg which is about 0.425 times the mass of the Sun at a distance of 1300 pc. The size of the cavity was 3.67° × 3.6°, whereas its core size was 0.531° × 0.255° located at R.A. (J2000) = 7h10m0.8s and Dec.(J2000) =15h55m30s. The minimum and maximum temperatures were between 20.24 ± 1.16 K and 18.63 ± 1.96 K respectively. In the core region, the average temperature was 19.53 K, approximately equal to Gaussian center 19.267 K with an offset temperature of 0.4 K showing that the core region of the cavity is dynamically stable. The Far-infrared loop was found to be located within a 1° radius around the high-velocity cloud HVC oriented by 45° to the plane of the sky. The inclination angle of the core of the loop was greater than 60° whereas the inclination angle for the larger structure was 13.71°. The Gaussian distribution of temperature was well fitted with the center of 19.267 K which shows that the cavity was in thermal equilibrium and the outer region with offset temperature of about 35 K suggesting that the loop was dynamically unstable possibly due to high-velocity cloud

scholarly journals Study of Two Far Infrared Cavities Nearby Asymptotic Giant Branch Stars Under Infrared Astronomical Satellite Maps

2019 ◽  
Vol 24 (2) ◽  
pp. 76-84
Author(s):  
A. K. Gautam ◽  
B. Aryal
Keyword(s):  
Far Infrared ◽  
Core Region ◽  
Dust Particles ◽  
Negative Slope ◽  
Agb Stars ◽  
Colour Temperature ◽  
The Core ◽  
Planck Function ◽  
Visual Extinction ◽  
Dust Mass

 Dust colour temperature, dust mass, visual extinction and Planck function with their distributions in the core region of two far infrared cavities (named FIC04+61 and FIC11-54) found within 3° of AGB stars namely AGB0409+6105 and AGB1105-5451 were studied. Dust colour temperature of the core region of the cavities was found to be (19.4 ± 0.93) K to (20.6 ± 0.65) K and (21.4 ± 0.51) K to (22.6 ± 0.23) K, respectively. The product of dust colour temperature and visual extinction was consistent in the order of 10-4. The contour maps showed that the low-temperature region has greater mass density and suggests that the distribution of dust mass is homogeneous and isotropic. The distribution of Planck function along with the extension (major diameter) and compression (minor diameter) found to be non-uniform distribution means dust particles were oscillating to get dynamical equilibrium. It further suggests that the dust particles in the cavities might not be in the thermal equilibrium possibly due to pressure-driven events of nearby AGB stars. A negative slope in the transition from 25 μm to 60 μm was our finding regarding far infrared spectral distribution in the cavities. It suggests that the number density of dust particles was less than expected in 60 μm regions.

scholarly journals Planck Function Distribution in the Far Infrared Cavity Nearby AGB Star at Galactic Latitude 0.6º

2020 ◽  
Vol 6 (2) ◽  
pp. 97-103
Author(s):  
A. K. Gautam ◽  
D. N. Chhatkuli
Keyword(s):  
Galactic Plane ◽  
Local Thermodynamic Equilibrium ◽  
Mass Density ◽  
Far Infrared ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Contour Maps ◽  
Planck Function ◽  
Visual Extinction ◽  
Dust Mass

A far infrared cavity nearby AGB star namely AGB2308+6058 was found to be located centered at R. A. (J2000)= 23h 06m 54.6s and Dec. (J2000)= 61° 16' 09.8". Distribution of dust color temperature, dust mass and visual extinction of the far infrared cavity have studied. In addition, the distribution of Planck function along the compression and extension of the cavity also has studied. This cavity has found to be located nearby the AGB star around far infrared loop G110+00 at 730 pc. It is close to the Galactic plane at galactic latitude 0.6° therefore the radiation field is strong and the diameter of the cavity is found to be greater than 0.2°. The dust color temperatures was found to be in the range 22.76 ± 0.14 K to 23.55 ± 0.29 K with offset 0.79 K. The contour maps of dust color temperature and dust mass showed that the low temperature region have greater mass density. Planck function showed non-uniform distribution along its extension and compression, suggesting that the dust and grains are not in the local thermodynamic equilibrium, possibly due to nearby AGB star. A clearly noted result is from counter map of dust mass and visual extinction that they showed consistent nature in their distribution.

scholarly journals A STUDY OF A PULSAR WIND DRIVEN STRUCTURE IN FAR-INFRARED IRAS MAP AT LATTITUDE -10º

2017 ◽  
Vol 22 (1) ◽  
pp. 1-9
Author(s):  
Ajay Kumar Jha ◽  
Binil Aryal
Keyword(s):  
Far Infrared ◽  
Density Variation ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Dust Structure ◽  
Infrared Astronomical Satellite ◽  
Mass Profile ◽  
Using Data ◽  
Astronomical Satellite ◽  
Galactic Longitude

A systematic search of dust structure in the far infrared (100 μm and 60 μm) IRAS (Infrared Astronomical Satellite) survey was performed using Sky View Observatory. In order to find the possible candidate, we used SIMBAD database to locate discrete sources in the region. A deep cavity-like isolated far infrared dust structure (size ~ 4.46 pc × 2.23 pc) at galactic longitude: 284.360o, galactic latitude: -9.549o was found at the distance of about 375 pc. We have studied the flux density variation and then calculated temperature and mass profile of the dust and excess mass using data reduction software ALADIN 7.5 within this region. The dust color temperature was found to lie in the range 23.40 K to 29.28 K. An offset temperature of about 6.0 K was found. The total mass of the dust structure was found to be about 2.55×1027 kg and the excess mass per pixel was 2.52×1024 kg. We also studied the rate of mass loading around the structure. The energy of the pulsar required to create that in homogeneity in the structure was calculated to be 5.04×1036 J. Possible explanations of results will be presented.Journal of Institute of Science and Technology, 2017, 22 (1): 1-9

scholarly journals Study of Dust Cavity around the White Dwarf WD 0352-049 in Infrared Astronomical Satellite Map

2021 ◽  
Vol 7 (2) ◽  
pp. 110-118
Author(s):  
M. S. Paudel ◽  
P. Bhandari ◽  
S. Bhattarai
Keyword(s):  
Flux Density ◽  
White Dwarf ◽  
Background Radiation ◽  
Three Dimensional ◽  
Far Infrared ◽  
Color Temperature ◽  
Cavity Structure ◽  
Dust Mass ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

In this work, we have studied the far-infrared images of the dust cavity around the White Dwarf WD 0352-049 available in Infrared Astronomical Satellite Map from Sky View Observatory. The size of the cavity is 24.48 pc × 8.10 pc. We have studied the relative infrared flux density and calculated the dust color temperature and dust mass. The temperature of the whole cavity structure lies between a maximum value 24.09 ± 0.50 K to a minimum 21.87 ± 0.61K with fluctuation of 2.22 K and an average value of 23.09 ± 1.11 K. The small fluctuation of dust color temperature suggests that the dust in cavity structure is evolving independently and less disturbed from background radiation sources. The color map shows the identical distribution of flux at 60 μm and 100 μm and the inverse distribution of dust color temperature and dust mass. There is a Gaussian-like distribution of relative flux density, dust color temperature and dust mass. The Gaussian distribution of temperature suggests that the dusts in cavity are in local thermodynamic equilibrium. The study of relative flux density and dust color temperature along the major and minor axis shows there is a sinusoidal fluctuation of flux and temperature, which might be due to the wind generated by White Dwarf located nearby the center of the cavity structure. The total dust mass of the dust is found to be 0.07 Mʘ and that of gas is 13.66 Mʘ. The Jeans mass of the structure is less than the total mass of gas in the structure, suggesting the possibility of star formation activity by gravitational collapse in the future. Also, the study of inclination angle suggests that the three-dimensional shape of the structure is uniform and regularly shaped.

scholarly journals Vortex Spinup Process in the Extratropical Transition of Hurricane Sandy (2012)

2019 ◽  
Vol 76 (11) ◽  
pp. 3589-3610 ◽  
Author(s):  
Jung Hoon Shin
Keyword(s):  
Structural Changes ◽  
Outer Region ◽  
Momentum Equation ◽  
Hurricane Sandy ◽  
Core Region ◽  
Local Wind ◽  
Extratropical Transition ◽  
The Core ◽  
Tangential Wind ◽  
Baroclinic Zone

Abstract This study utilizes the quasi-Lagrangian azimuthal momentum equation (i.e., budget calculation) and 1.667-km-resolution numerical simulation data to study the intensity and structural changes in Hurricane Sandy’s extratropical transition. The results indicate that after the onset of extratropical transition, Sandy maintains an eyewall-like convection and warm core in the core region and has a frontal structure in the outer region. In the outer region, baroclinicity-driven frontal convection induces extensive planetary boundary layer (PBL) inflow, causing an inward advection of absolute angular momentum (AAM) per unit radius, which generates outer local wind maxima and expands Sandy’s outer wind field through a spinup process. Moreover, because the outer tangential wind velocity accelerates in a frontal convection, local wind maxima associated with fronts can expand to the outer sides of frontal regions. Frontal convection increases AAM in the outer region, providing the precondition for reintensification; however, the front itself cannot cause Sandy’s reintensification. The eyewall-like convection in the core region still plays an important role in Sandy’s reintensification. When the baroclinic zone, where a strong horizontal temperature gradient exists, approaches the core region, the eyewall-like convection is enhanced because the warm, moist air of the core region is lifted by the cold, dry air associated with the approaching baroclinic zone. Consequently, owing to the enhancement of eyewall-like convection, the PBL inflow, which extends from the outer region to the core region, develops. This inflow increases the inward transportation of the outer frontal region’s high-AAM air, thus leading to spinning up the core region’s wind and reintensification.

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