scholarly journals Study of a Far Infrared Cavity Around a Post-Asymptotic Giant Branch Star at Galactic Latitude -0.1º

2020 ◽  
Vol 6 (1) ◽  
pp. 97-104
Author(s):  
A. K. Gautam
Keyword(s):  
Galactic Plane ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Dust Particles ◽  
Galactic Latitude ◽  
Continuous Increase ◽  
Asymptotic Giant Branch Star ◽  
Planck Function ◽  
Visual Extinction

We present dust color temperature, Planck function and visual extinction distributions of a far infrared cavity FIC19+30 found to be located around post-AGB star namely AGB20+29 at the galactic plane. Minimum and maximum dust color temperature of the core region of the cavity was found to be (22.17±0.23) K and (22.41±0.29) K respectively with offset value 0.24 K which suggests that the cavity is isolated and stable. The product of dust color temperature and visual extinction was found to be in the order of 10-4 K mag. The distribution of Planck function along the extension (major diameter) and compression (minor diameter) was found to be non-uniform distribution. Specifically dust particles are oscillating in order to get dynamical equilibrium which may be the cause of grain temperature. 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. There is continuous increase in flux density with increase in wavelength as in case of nebula which suggests that number density of dust particles increase according to the increase in wavelength and vice-versa.

scholarly journals Study of Dust Properties of two Far Infrared Cavities near by Asymptotic Giant Branch stars under Infrared Astronomical Satellite Maps

2020 ◽  
pp. 60-71
Author(s):  
M. Tiwari ◽  
S.P. Gautam ◽  
A. Silwal ◽  
S. Subedi ◽  
A. Paudel ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Dust Particles ◽  
Planck Function ◽  
Visual Extinction ◽  
Contour Plots ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

The physical properties such as dust color temperature, dust mass, visual extinction, and Planck function with their distribution in the core region of two far-infrared cavities, namely FIC16-37 (size ~ 4.79 pc x 3.06 pc) located at R.A. (J2000): 16h 33m 57.25s & Dec. (J2000): -37d 47m 04.3s, and FIC12-58 (size ~ 22.54 pc x 14.84 pc) located at R.A. (J2000): 12h 52m 50.08s & Dec. (J2000): -58d 08m 55.02s, found within a galactic plane -10o  to +10o  nearby Asymptotic Giant Branch (AGB) stars namely AGB15-38 (R.A. (J2000): 15h 37m 40.74s & Dec. (J2000): -38d 20m 24.6s), and AGB12-57 (R.A (J2000): 12h 56m 38.50s & Dec. (J2000): -57d 54m 34.70s), respectively were studied using Infrared Astronomical Satellite (IRAS) survey. The dust color temperature was found to lie in the range of 23.95 ± 0.25 K to 23.44 ± 0.27 K with an offset about 0.5 K for FIC16-37, and 24.88 ± 0.27 K to 23.63 ± 0.98 K with an offset about 1 K for FIC12-58. The low offset in the dust color temperature indicated the symmetric distribution of density and temperature. The total mass of the cavities FIC16-37 and FIC12-58 were found to be 0.053 M☉ and 0.78 M☉, respectively. The contour plots of mass distribution of both of the cavities was found to follow the cosmological principle, suggesting the homogeneous and isotropic distribution of dust masses. The plot between temperature and visual extinction showed a negative correlation, suggesting that higher temperature has lower visual extinction and vice-versa. The distribution of Planck function along major and minor diameters of both of the cavities was found to be non-uniform, indicating oscillation of dust particles to get dynamical equilibrium. It further suggested the role of pressure-driven events nearby both cavities and suggested that dust particles are not in thermal equilibrium along the diameters.

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 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 Dust Structure nearby Asymptotic Giant Branch Star using IRAS Survey

2021 ◽  
Author(s):  
Sujan Prasad Gautam ◽  
Ashok Silwal ◽  
Manish Khanal ◽  
Ajay Kumar Jha
Keyword(s):  
Spectral Distribution ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Asymptotic Giant Branch Star ◽  
Visual Extinction ◽  
Cavity Structure ◽  
Infrared Spectral ◽  
Infrared Background ◽  
Branch Star

Abstract This study performed an investigation of a dust environment, in the far-infrared bands (60 and 100 µm) of Infrared Astronomical Satellite (IRAS) survey, using the Sky View Virtual Observatory (https://skyview.gsfc.nasa.gov/current/). A far-infrared cavity structure (depression in the far-infrared background emission) of major diameter ∼ 61.8 pc and minor diameter ∼ 46.5 pc, in the sky coordinate, R.A. (J2000) = 21h 32m 44.47s and Dec. (J2000) = +55d 15m 16.8s, at a distance ∼ 3.58 kpc was found to lie around a carbon-rich Asymptotic Giant Branch star. We studied the temperature and mass of the dust, radiation intensity distribution, visual extinction, and far-infrared spectral distribution of the cavity structure using the softwares Aladin v2.5, SalsaJ, and ORIGIN 8.5. The range of temperature of dust was observed between 22.24 ± 0.81 K to 23.27 ± 0.21 K, and the entire mass of the cavity was determined to be 2.19 × 1031 kg. In addition, the fluctuating nature of the dust color temperature and Planck function was observed along major and minor diameters of the structure. Moreover, an opposite relationship of dust color temperature and visual extinction was found within the structure. Finally, from the far-infrared spectral distribution, abrupt reduction at 60 µm flux rather than a continual increase was observed, the connection between the AGB wind and the ambient interstellar medium could be the possible reason behind this. Our results obey the similar trends obtained for the other cavity structures in the previous studies; these findings validate the existing results for a new cavity structure around AGB star within the galactic coordinate -6o < b < +6o.

scholarly journals Dust Properties of Two New Cavity Structures Nearby Asymptotic Giant Branch Stars: The IRAS Survey

2021 ◽  
Vol 26 (2) ◽  
pp. 119-126
Author(s):  
Sujan Prasad Gautam ◽  
Ashok Silwal ◽  
Mijas Tiwari ◽  
Seema Subedi ◽  
Manish Khanal ◽  
...  
Keyword(s):  
Galactic Plane ◽  
Region Of Interest ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Dust Particles ◽  
Negative Slope ◽  
Asymptotic Giant Branch Stars ◽  
Infrared Spectral ◽  
Giant Branch Stars

We studied the dust properties of two cavity structures (namely FIC21+54 and FIC16-56) nearby Asymptotic Giant Branch stars using Infrared Astronomical Satellite (IRAS) maps. Dust color temperature, Planck function, dust mass, and visual extinction with their distribution within the region of interest were examined. The temperature of dust was found to lie in the range of 22.24 ± 0.81 K to 23.27 ± 0.21 K, and 25.12 ± 0.43 K to 26.17 ± 0.62 K, and the mass of dust was obtained within the range of 4.21 × 1026 kg to 3.6 × 1027 kg, and 2.1 × 1027 kg to 3.31 × 1028 kg, for FIC21+54 and FIC16-56, respectively. Some unusual behaviors on the distribution of dust temperature indicated the effect of nearby sources within the studied structures. Moreover, we observed the trend of dust particles along the major and minor diameters, and plots represented that the particles were oscillating with a sinusoidal pattern in both cavities. The negative slope between 25 µm and 60 µm in far-infrared spectral distribution was encountered for both structures, which portrayed less number density of particles in 60 µm band; interaction between AGB wind and the ambient interstellar medium could be the possible reason behind this. These findings support the prior results for two new cavity structures nearby AGB stars within the galactic plane -10° < b < +10°.

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 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 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 Study of dust color temperature and visual extinction distribution of a far infrared cavity at 60 and 100 µm IRAS map around the AGB star at galactic latitude 8.6⁰

BIBECHANA ◽  
2020 ◽  
Vol 17 ◽  
pp. 42-49
Author(s):  
A K Gautam ◽  
B Aryal
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Grain Structure ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Visual Extinction ◽  
Stable Product ◽  
Infrared Astronomical Satellite ◽  
Dust Grain ◽  
Astronomical Satellite

The dust-grain structure in the far infrared region under IRAS (Infrared Astronomical Satellite) Survey was studied using sky view virtual observatory. In order to find the possible far infrared cavity, we used SIMBAD database. In this paper, we discuss about the dusty environment of a far infrared cavity around the AGB star located at R.A. (J2000) =01h 41m 01s and Dec (J2000) = 71o 04’ 00” lying within far infrared loop G125+09  in the far infrared IRAS maps. A cavity like structure (major diameter ∼ 2.55 pc & minor diameter ∼ 0.77 pc) is found to lie at R.A. (J2000)= 01h 46m 57.2s and DEC (J2000)= 71o 24’ 57.1”, located at a distance ∼ 220 pc from the star. We studied the distribution of flux density, dust color temperature, dust mass, inclination angle, visual extinction and FIR spectral distribution of the cavity. We further studied the distribution of Planck function along extension and compression. The dust color temperature is found to lie in the range (19.7±0.65) K to 21.1±0.35) K which shows the cavity is isolated and stable. Product of visual extinction and dust color temperature is found to be less than one. A possible explanation of the results will be discussed. BIBECHANA 17 (2020) 42-49

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

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