Dust Color Temperature Research Articles

Dust Properties around the Dust Cloud nearby White Dwarf LAWD 84 in IRIS and AKARI Data

An isolated dust cloud is discovered nearby the White Dwarf LAWD 84, located at (RA, DEC) (J2000): 21h19m36.53s, -55°50'4.47'', in the infrared data of Improved Reprocessingof the IRAS (IRIS) and AKARI infrared survey, within angular size 1.0° ×1.0°. The isolated region of dust cloud is found to be broken into the two parts both in IRIS and AKARI data, named as IRIS-UP, IRIS-LOW, AKARI-UP and AKARI-LOW. The isolated region of flux at 100 μm in IRIS and 140 μm in AKARI is also studied separately. The dust color temperature (Td) and dust mass (Md) are calculated from the infrared flux in both data. The average Td is found to be ∼24 K in IRIS data and ∼20 K in AKARI data in both parts. The ratio of dust mass in total region to isolated region is found ∼ 2.0 in IRIS-UP and AKARI-UP but the ratio is 5.06 in IRIS-LOW and 3.19 in AKARI-LOW clouds. The regression analysis between the infrared fluxes at two wavelength shows a linear relation between the infrared fluxes in both clouds, whereas there is no any preferred relation observed between the infrared flux (both wavelength) and dust color temperature but a direct linear relationship between infrared flux and dust color temperature, and inverse parabolic relationship obtained between the dust color temperature and dust mass in all clouds. The qualitative analysis of contour map of infrared flux, temperature and mass supports this result. Furthermore, the inclination angle of the each clouds, background point sources, Jeans Criteria and Gaussian distribution of the dust color temperature are studied within both clouds to explain the possible ongoing physical phenomenon within the clouds.

A New Far Infrared Cavity Near White Dwarf WD0245+541

Abstract: A new far infrared dusty cavity of size 17.4' x 8.6’ at 100 m IRAS (Infrared Astronomical Satellite) map located 0.15o northwest of white dwarf WD0245+541 is investigated. We present dust color temperature, dust mass, and the Planck function distributions in and around the cavity (FIC0248+542). The dust color temperature has been determined to fall within the range of 23.0 to 27.3 (±1.9) K, while the dust mass is found to be 0.8 x 1026 kg. The Planck function distribution along the white dwarf is observed to be non-uniform. Keywords: White Dwarf, Far infrared cavity, Dust color temperature, Planck function, Gaussian distribution.

Distribution of dust color temperature, dust mass and planck’s function around C-rich AGB star: IRAS 19558+3333 using IRIS, AKARI, and WISE Surveys

The dust properties of C-rich AGB (Asymptotic giant branch) star IRAS 19558+3333 located at right ascension (R.A.) (J2000) = 19h 57m 48.440s and Declination (J2000) = +330 41h 21.250s was studied. The FITS image of this AGB star was obtained by SkyView Virtual Observatory in IRIS, AKARI, and WISE surveys respectively. The flux of ambient medium in the wavelength range of IRIS 60 μm and 100 μm, AKARI 90 μm and 140 μm and WISE 12 μm and 22 μm was calculated along with the physical properties like dust color temperature, dust mass, Planck’s function and visual extinction of the candidate at a distance of 3415.420 pc. The minimum and maximum dust mass is found to be 1.606× 1021 kg (8.030 × 10−10 M⊙), and 7.013 × 1020 kg (3.506× 10−10 M⊙) in IRIS, 2.739 × 1022 kg (1.369× 10−8 M⊙), and 1.292 × 1022 kg (6.460 × 10-9 M⊙) in AKARI and 2.297 × 1020 kg (1.148 × 10−10 M⊙) and 3.013 × 1019 kg (1.506 × 10−11 M⊙) in the WISE survey and the dust color temperature of the corresponding C-rich star average value was found to be 24.230 ± 0.229 K in IRIS, 16.780 ± 0.189 K in AKARI and 123.750 ± 0.430 K in WISE survey. The temperature in WISE was higher than that of the AKARI and WISE surveys.

IRAS 00450+7401 and the Mid-infrared Fade/Burst Cycle of R Coronae Borealis-type Stars

We present optical and infrared imaging and spectroscopy of the R Coronae Borealis-type (R Cor Bor) star IRAS 00450+7401. Optical spectra further confirm its classification as a cool R Cor Bor system, having a hydrogen-deficient carbon star spectral subclass of HdC5 or later. Mid-infrared spectroscopy reveals the typical ∼8 μm “hump” seen in other R Cor Bor stars and no other features. A modern-epoch spectral energy distribution shows bright emission from hot dust having T dust > 600 K. Historical infrared data reveal generally cooler dust color temperatures combined with long-term fading trends, but provide no discernible correlation between flux level and temperature. Investigating the most mid-infrared variable R Cor Bor stars found in IRAS, AKARI, and WISE data reveals similar fading trends, bursts that can show a factor of up to 10 change in flux density between epochs, and blackbody-fit dust color temperatures that span 400–1300 K. While some R Cor Bor stars such as IRAS 00450+7401 appear to undergo fade/burst cycles in the mid-infrared, significant gaps in temporal coverage prevent conclusively identifying any preferred timescale for their mid-infrared variability and circumstellar dust temperature changes.

Dust properties around NGC 7023 nebula in interstellar medium using IRIS, AKARI, and WISE survery


 
 
 
 We have studied the physical properties of dust around the nebula NGC 7023. The physical properties have been studied at 60 μm and 100 μm in the IRIS survey, 90 μm and 140 μm in the AKARI survey, and 12 μm and 22 μm in the WISE survey at the right ascension (R.A.) (J2000) = 21h01m35.60s, declination (J2000) = + 68o10m10.0s. The nebula is found at a distance of 335.82 pc from us. We found the dust color temperature is in the range between 36.19 K ± 0.03 K to 24.49 K ± 0.03 K with an average dust color temperature of 28.24 K ± 0.03 K in IRIS survey and a range between 38.80 K ± 0.25 K to 21.00 K ± 0.25 K with an average dust color temperature 26.39 K ± 0.25 K in AKARI survey. Similarly, in WISE, the dust color temperature was found in the range between 130.92 K ± 0.01 K to 88.71 K ± 0.01 K with an average of 104.76 K ± 0.25 K. The temperature in WISE is higher than that of the IRIS and AKARI survey. We have also calculated the dust mass, whose average value was found to be 1.18 x 1027 kg (5.93 x 10−4 M⊙) in IRIS, 1.06 x 1028 kg (5.33 x 10−3 M⊙) in AKARI, and 1.06 x 1027 kg (5.33 x 10−4 M⊙) in the WISE survey. We have also studied the visual extinction parameter due to such dust in infrared bands. This work will contribute to understanding infrared band emission from the dusty region around the nebular structure in the interstellar medium.
 
 
 

Properties of dust in the North - East part of Perseus Cloud within the open cluster IC 348 using data from IRIS and AKARI

In this work, we have studied the dust properties of the North-East part of Perseus cloud having a size of 0.5o × 0.5o located at RA (ICRS): 56.14o DEC (ICRS): +32.15o, within the Open Cluster IC 348, using IRIS and AKARI data. An isolated region of size 0.39o×0.23o in IRIS and 0.34o×0.16o in AKARI data is detected within it. The infrared fluxes extracted using Aladin v11.0 are used to study the dust temperature and dust mass. The distance of the selected dust structure is calculated using Gaia EDR3, which is 309.98 pc. The infrared flux density is found to be increased for long-wavelength data. The average dust color temperature calculated from short-wavelength IRIS data is more than that calculated from long-wavelength AKARI data, which are 26.34 K±0.11 K for IRIS and 17.63 K±0.02 K for AKARI data. The mass of dust within the entire dust structure is 0.06 Mʘ for IRIS data and 37.44 Mʘ for AKARI data. Jeans mass for isolated region gives contradictory results in two surveys, for IRIS survey total mass is smaller than Jeans mass but for AKARI survey the total mass is larger than the Jeans mass. A good correlation between infrared fluxes is noticed for linear regression. The study background sources observed from the SIMBAD database explore the large number of stars, X-ray sources, YSOs, etc., embedded within the dust structure; some of them are responsible for dust heating and some for the contribution of dust mass. The contour map shows the identical distribution between infrared fluxes, dust color temperature and Planck’s function and dissimilar distribution between dust mass and visual extinction in IRIS and AKARI data. The high temperature at the central region suggests that the core of dust structure is thermally active, radiating the large thermal radiation in comparison to the outer region.

Study of dust properties nearby pulsar J0302+2252 using Iris, Akari and wise surveys

A search of dust structures nearby the pulsar J0302+2252 in IRIS, AKARI, and WISE surveys were performed using Skyview Observatory (http://skyview.gsfc.nasa.gov). The physical properties have been studied at 60µm & 100µm in the IRIS survey, 90µm & 140µm in the AKARI survey, and 12µm & 22µm in the WISE survey at right ascension (R.A.) (J2000)=03h 02m 31.99s and Declination (Decl.) (J2000)=+ 220 52m 12.10s . In this work, we have studied the physical properties such as Dust color temperature, Planck’s function, Visual extinction, and Mass profile of the dust using the data reduction software ALADIN v11. The dust color temperature is found to be 22.271 ± 0.261K in IRIS, 22.343 ± 0.939 K in AKARI, and 278.74 ± 0.067 K in WISE. Also, the dust mass is found to be 2.286 × 1027 kg (1.149 × 10-3 M⊙ ) in IRIS, 8.800 ×1026 kg (0.416× 10-3 M⊙ ) in AKARI and 5.220 ×1025 kg (0.026 ×10-3 M⊙ ) in WISE. The average visual extinction is found to be 1.372 ×10-13 mag. In IRIS, 4.970 ×10-14 mag. In AKARI and 1.673 ×10-15 mag. In WISE. The dust color temperature and dust mass distribution show a very good agreement with Gaussian. The Contour plots of dust color temperature and dust mass show inverse relation between them in all three bands IRIS, AKARI, and WISE.

Comparative Study of Dust Properties around White Dwarf PG 1225-079 in IRIS, AKARI and WISE Data

In this work, dust properties around the White Dwarf PG 1225-079 located at RA (J2000): 12h 27m 47.35s, DEC(J2000): -08° 14’ 37.97” is studied extensively using the publicly available data from Improved Reprocessing of IRAS Survey (IRIS), AKARI infrared survey and Wide field Infrared Survey Explorer (WISE). The bipolar dust structure hardly resolved in IRIS (60 μm and 100 μm) is clearly resolved in AKARI (90 μm and 140 μm) and WISE (12 μm and 22 μm) images. The dust color temperature and dust mass are calculated from the infrared flux density. The average value of dust color temperature in isolated dust structure is 27.57 K for IRIS (I1). For isolated upper and lower dust clouds the average temperatures are; 22.64 K and 22.63 K for AKARI (A1 and A2), 295.34 K and 296.85 K in WISE (W1 and W2) data. A wide range of temperatures suggests the bipolar dust structure is dynamically active. The mass of dust is found to be 3.44 × 1025 kg in IRIS (I1), 1.82 × 1026 kg and 5.89×1026 kg in two bipolar regions in AKARI (A1 and A2) and 1.12 ×1026 kg and 1.14×1026 kg in WISE (W1 and W2). A good relation is found between the infrared flux in all survey data with r2 value 0.83 in IRIS (I1) and more than 0.90 in AKARI (A1, A2) and WISE (W1, W2) data. SIMBAD database explore some sources including Supernova Remnants nearby the dust which might be the progenitor of dust as well as the contributor of energetic radiation. The Gaussian modeling of temperature is found to be deviated from normal shape. The contour plot of dust color temperature and dust mass shows non uniform variation among the IRIS, AKARI and WISE survey. The relation between infrared flux, dust color temperature and dust mass within the dust clouds are presented.

Study of an Isolated Dust Structure Nearby the White Dwarf WD0011-399 Using IRIS, AKARI, and WISE Data

During the asymptotic giant branch (AGB) phase, a major fraction of mass is spread by the stars (0.6 - 10 M⊙) in the interstellar medium (ISM) in the form of dust. In the left phase of the post-main sequence evolution in the Hertzsprung-Russell (HR) diagram, these dust are found to be surrounding the white dwarfs (WD). Some small fraction of dust is also formed in the circumstellar shells and cavities around WD which is usually a source of infrared (IR) excess. The formation and evolution of such IR dust structures are the results of high-pressure events such as the Helium shell flash (thermal pulse) and stellar winds, and such structures are crucial in the study of interaction phenomena in ISM. This research project is focused on the study of an isolated dust structure near the white dwarf WD0011-399 located at R.A. (J2000) 00h 13m 47.48s and Dec. (J2000) -39° 370 24.2800 using Improved Reprocessing of the IRAS (IRIS), AKARI and Wide-field Infrared Survey Explorer (WISE) surveys from SkyView Virtual Observatory along with SIMBAD Astronomical Database and Gaia Archive of ESA. The size of the cavity under study is 7.43 pc×2.90 pc, 2.99pc×0.99pc, and 1.26×0.53pc with an inclination angle of 71.12°, 75.73°, and 68.48° respectively in IRIS, AKARI and WISE data suggesting the cavity is neither a face-on nor an edge-on. The relative flux density of the region has been studied through pixel extraction of Far-Infrared (FIR) images and dust color temperature along with dust mass has been calculated. Using IRIS data, the temperature of the isolated region is found between a maximum value of 36.82±4.30 K to a minimum of 22.59±2.32 K with an offset of 14.23 K. The average temperature of the region is 28.22±0.18 K. Following similar procedures for AKARI data, the temperature is found between a maximum of 26.37±3.56 K and a minimum of 16.32±1.47 K with an offset of 10.06K. The average temperature is 19.25±0.15 K. Similarly, using WISE data, the temperature is found between a maximum of 353.72±18.54 K and a minimum of 307.24±4.69 K with an offset of 46.48K. The average temperature is 316.62±0.81 K. High value of offset temperature suggests that the cavity might be evolving with disruptions from background radiative sources. Approximately Gaussian distribution of the temperature in all the surveys implies that the region might be tending towards local thermodynamic equilibrium. The total mass of the structure is estimated to be around 0.03±1.5×10−6M⊙, 1.6×10−3±1.4×10−5 M⊙, and 10−7±3×10−10 M⊙ using IRIS, AKARI, and WISE data respectively. The Jean’s mass of the structure is calculated assuming the structure is a non-degenerate gas, which is estimated around 2001.93M⊙, 178.44M⊙, and 121.47M⊙ respectively using IRIS, AKARI, and WISE data. Since Jean’s mass is much greater than the mass of the structure there seems no possibility of star formation within the region of interest. The color maps illustrate identical distribution for all wavelengths, however, no significant relation is observed between dust color temperature and dust mass.

Studies of Dust Properties in Sub−Structures around White Dwarf WD 0307+077 in IRIS Survey

A huge dust structure of size 3° ×3° consisting of many sub−structures of dust nebulae and dust cavities is discovered around the WD 0307+077, located at RA (ICRS): 47.59° , DEC (ICRS): +7.84° , in far−infrared image of IRIS survey. Infrared flux density at 60 µm and 100 µm are used to calculate dust color temperature and dust mass in dust structure and all sub−structures. The contour plot is used to visualize the variation of infrared flux, dust color temperature and dust mass within all sub−structures. The inclination angle of isolated region of sub−structures is calculated to know the shape of the dust cloud. It is found that the dust color temperature of all the nebulae and cavities lies between the 20 K to 24 K, with range not more than 3 K. This range of temperature suggests that the sub−structures are moving towards the thermal stability. The dust mass shows the similar mass composition within all sub−structures, with variation of just one order magnitude. The linear regression shows a very good linear relation between between the infrared flux at 60 µm and 100 µm wavelength with regression coefficient more than 0.90 in five sub−structures and more than 0.78 in remaining two. The inclination angle of shows the all sub−structures are clearly edge−on in shape having inclination angle i > 45° . The Gaussian distribution of dust color temperature in all sub−structures shows more or less deviation from Normal distribution, the background sources observed in the SIMBAD database are suspected for this deviation.

Distribution of Dust Color Temperature, Planck’s Function, and Dust Mass around PSR J1240-4124

The dust properties in the interstellar medium play an important role in structure formation and extinction of highenergy radiation. This study performed an investigation of the physical properties like distribution of dust color temperature, Planck’s function, and dust mass of the cavity around the pulsar PSR J1240-4124 in the IRIS and the AKARI surveys. In our study, the dust color temperature in the IRIS survey is found to be in the range of 23.607 ± 0.012 K to 24.342 ± 0.012 K with an offset of 0.735 K. Such low offset temperature indicates that the isolated cavities are in thermal equilibrium. In the case of the AKARI survey, the dust temperature was found to be in the range of 16.123 ± 0.017 K to 18.802 ± 0.017 K with an offset of 2.679 K. The average dust mass in IRIS survey is found to be 2.1 × 10−4 M⊙ and that of the AKARI is 8.1× 10−4 M⊙. The size of the structure in the IRIS map is 14.62 pc × 6.24 pc and that of the AKARI map is 5.80 pc × 0.17 pc. The angle of inclination for the selected cavity region is found to be 73.330° in IRIS and that of AKARI is 110.260° . We have tried to present the relationship among the different physical parameters and compare the results in the IRIS and the AKARI surveys. Our findings are similar to those obtained in previous studies of other cavity structures around pulsars. This confirms the validity of the existing results for a new cavity around PSR J1240-4124.

Radio Variability and Broad-Band Spectra of Infrared Galaxies with and without OH Megamaser Emission

We study the radio variability of galaxies with and without sources of hydroxyl (OH) megamaser radiation based on the continuum radio measurements conducted in 2019-2022 with the radio telescope RATAN-600 at frequencies of 2.3, 4.7, 8.2, and 11.2 GHz. Presumably, radio continuum emission significantly affects the megamaser radiation brightness, therefore, such a characteristic as the variability of radio emission is important for determining the OHM galaxies parameters. With additional data from the literature, the parameters of radio variability on a time scale up to 30 years were estimated. The median values of the variability index for 48 OHM galaxies are in the range $V_{S}=0.08$-$0.17$, and for 30 galaxies without OH emission they are $V_{S}=0.08$-$0.28$. For some individual galaxies in both samples, flux density variations reach 30-50%. These sources either are commonly associated with AGNs or reveal active star formation. Generally, the variability of luminous infrared galaxies with and without OH megamaser emission is moderate and of the same order of magnitude on long time scales. From estimating the spectral energy distribution parameters in a broad frequency range (from MHz to THz), we determined the spectral index below 50 GHz and the color temperatures of dust components for megamaser and control sample galaxies. At a level of $\rho<0.05$, there are no statistically significant differences in the distribution of these parameters for the two samples, as well there are no statistically significant correlations between the dust color temperatures and the variability index or luminosity in the OH line.

Studies of the Properties of Dust Structure Nearby the Supernova Remnants G053.41+00.3, G053.9+00.2 and G053.1+00.3 using Data from IRIS and AKARI

The search of isolated dust structure is performed around the Supernova Remnants using SkyView Virtual Observatory in IRIS and AKARI survey. An isolated dust structure at Galactic Longitude: 53.54° and Galactic Latitude: +0.04° (RA: 292.56°, DEC: 18.24°) is selected for this work. The intensity of infrared fluxes are extracted from the FITS image using Aladin v2.5 and v11.0 software. The dust color temperature and dust mass are calculated from infrared flux. The distribution of infrared fluxes, dust color temperature and dust mass are studied via color map and Gaussian plot using Python 3.8. The dust color temperature is found larger in IRIS data but the dust mass is found more in AKARI data. We use Gaia EDR3 for the calculation of distance, which is 1667.89 pc. The background sources within the dust structure is studied using SIMBAD database. The color map shows an identical distribution for infrared fluxes in both IRIS and AKARI data; but for dust color temperature and dust mass, the distribution is different. The large fluctuation of temperature indicates that dust structure is beyond the local thermodynamicequilibrium. The distribution of infrared fluxes and dust color temperature deviates from Gaussian nature, indicating the dust structure is not evolving independently and the background radiation sources such as Supernova Remnants, Pulsars, etc. are playing major roles for the asymmetrical distribution. A study of inclination angle suggests the dust structure is non-uniform and irregular in its internal morphology. A good correlation between infrared fluxes is observed in both IRIS and AKARI data. Also, an inverse relation between dust color temperature and spectral index is observed for both data. It can be concluded that the high radiation sources within and outside the dust structure are playing a major role in the asymmetrical distribution of infrared flux and dust color temperature.

Dust Properties of Super-Nova Remnant (Crab Nebula) Using AKARI Survey

We present the distribution of dust color temperature, Planck's function, dust mass, and visual extinction in the far-infrared (140 μm and 90 μm) AKARI surveys of the Crab Nebula using Sky View Virtual Observatory. With a systematic search of a supernova remnants, we found Crab Nebula at R. A. (J2000) / Decl. (J2000) = 05h 34' 31.94"/+22° 00' 52.20". The maximum flux is found to be 145.94 MJysr-1 at 140 μm and 177.01 MJysr-1 at 90 μm wavelength. The total dust mass of the Supernova remnant is estimated to be 6.11×1039 kg (3.07×109 Mʘ) and the dust color temperature is found in the range between 31.16 K to 47.11 K with mean value of temperature of 38.07 K. Similarly we obtained the value of Planck’s function in the range of 3.96 × 10-15 Wm-2sr-1Hz-1 to 1.96 × 10-14 Wm-2sr-1Hz-1 with average value 9.59 × 10-15 Wm-2sr-1Hz-1. The value of visual extinction ranges from 9.21 × 10-14 mag to 2.70 × 10-13 mag with mean value of 1.57 × 10-13 mag. The distribution trend of flux, dust color temperature, and Planck’s function are nearly similar, whereas dust mass and visual extinction follow an inverse relationship with the previous three parameters.

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

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° &lt; b &lt; +10°.

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

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.

A study of dust structure nearby white dwarf WD1334-678

A low flux density region nearby white dwarf WD1334-678 in the 140 µm AKARI survey maps has been systematically searched and found a far-infrared cavity centered at R.A. (J2000) = 13h38m14.4s, Dec.(J2000) = −68◦40’42”, in which minimum flux is 19.5 MJy/sr at 90 µm wavelength. The physical properties (Size, dust color temperature, dust mass) and thermodynamic property (Planck function distribution) of the cavity using 140 µm and 90 µm AKARI survey data. The size of the cavity is found to be 0.17◦× 0.12◦ has been presented. The dust color temperature is found in the range 17.70 ± 0.01 K to 18.81 ± 0.01 K. The Plank function distribution along major and minor diameters shows a very good agreement with sinusoidal fitting. The period of oscillation of dust particles along major and minor diameters are 3.2 Wm-2Sr-1Hz-1arcmin-1and 1.6 Wm-2Sr-1Hz-1arcmin-1, respectively.&#x0D; BIBECHANA 18 (2) (2021) 130-137&#x0D;

Study Of A Far Infrared Cavity At The Galactic Plane

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.

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

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 &amp; 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 &amp; 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 &amp; Dec. (J2000): -38d 20m 24.6s), and AGB12-57 (R.A (J2000): 12h 56m 38.50s &amp; 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.

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

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.