scholarly journals A Study of Dust Structure around AGB Star in 60 and 100 μm IRAS Survey at Latitude 54.68º

2017 ◽  
Vol 4 (1) ◽  
pp. 67
Author(s):  
Arjun Kumar Gautam ◽  
Binil Aryal
Keyword(s):  
Minimum Temperature ◽  
Far Infrared ◽  
Density Variation ◽  
Asymptotic Giant Branch ◽  
Infrared Range ◽  
Virtual Observatory ◽  
Agb Stars ◽  
Dust Structure ◽  
Mass Losses ◽  
Mass Profile

<p class="Default">We have studied about the evolution of Asymptotic Giant Branch (AGB) stars, mass losses from them and a systematic search of AGB stars in J2000 coordinate system provided by K. W. Shu &amp; Y. J. Kwon (2011) of dust structure in the far infrared range (100 μm and 60 μm). For dust structure IRAS survey was performed using Sky View virtual Observatory. The FITS images downloaded from sky view was processed using software Aladin v 2.5. A cavity like structure (major diameter∼1.93 pc &amp; minor diameter∼ 0.89 pc) lies in the coordinate of R. A. (J2000) 04h 15m 03s and DEC (J2000) 54d 41m 00s was found at the distance∼ 240 pc. We studied the flux density variation and the temperature variation about major diameter, minor diameter and the distance between minimum temperature and minimum flux within the structure. We observed the variation of the temperature is 20.53 K to 21.09 K, with the offset of about 0.56 K, which show the cavity is independently evolved. The mass profile of each pixel of the structure was also calculated using this temperature.</p><p><strong>Journal of Nepal Physical Society</strong><em><br /></em>Volume 4, Issue 1, February 2017, Page: 67-77</p>

Dust Structure around AGB Star in 60μm and 100 μm IRAS Survey at Latitude 16.10°

2017 ◽  
pp. 48-53
Author(s):  
Arjun Kumar Gautam
Keyword(s):  
Coordinate System ◽  
Minimum Temperature ◽  
Far Infrared ◽  
Density Variation ◽  
Virtual Observatory ◽  
Dust Structure ◽  
Cavity Structure ◽  
Infrared Astronomical Satellite ◽  
Mass Profile ◽  
Astronomical Satellite

A systematic search in the range of J2000 coordinate system provided by K.W. Shu & Y.J. Kwon (2011) of dust structure in the far infrared (100 μm and 60 μm) IRAS (Infrared Astronomical Satellite) survey was performed using Sky View virtual Observatory (1) so that some interesting isolated cavity structures surrounding the cavity structure were expected. The FITS images downloaded from sky view (1) was processed using software Aladin v 2.5. A cavity like structure (major diameter ∼ 3.57 pc & minor diameter ∼ 1.19 pc) lies in the coordinate of R.A. (J2000) 06h 31m 05s and DEC (J2000) 16d 06m 00s was found at the distance ∼ 310 pc (5). We studied the flux density variation and the temperature variation about major diameter, minor diameter and the distance between minimum temperature and minimum flux within the structure. We observed the variation of the temperature is 20.53 K to 21.42 K, with the offset of about 0.89 K, which shows the cavity is independently evolved. The mass profile of each pixel of the structure was also calculated using these temperature.The Himalayan Physics Vol. 6 & 7, April 2017 (48-53)

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 Dust Structure around two Asymptotic Giant Stars at Latitude 32° & 40.67°

2017 ◽  
pp. 41-47
Author(s):  
A. K. Jha ◽  
D. R. Upadhyay
Keyword(s):  
Infrared Image ◽  
Far Infrared ◽  
Density Variation ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Dust Structure ◽  
Outflow Velocity ◽  
Cavity Structure ◽  
Mass Outflow ◽  
Using Data

We studied the dust structures in 60μm and 100μm infrared image around the two asymptotic giant branch (AGB) stars. A systematic search of dust structure in the far infrared (100 μm and 60 μm) Infrared Astronomical Satellite (IRAS) survey was performed using Sky View Observatory. In order to find the possible candidate of cavity structure not yet studied, we used SIMBAD database to locate discrete sources in the region. A new relatively symmetric spherical cavity like structure (size: 1.354 pc × 0.971 pc) for candidate I and (size: 1.424 pc × 0.925pc) for candidate II at R.A.(J2000) =04h46m13.84s, Dec.(J2000) = +32°31’39.6’’ and 05h05m59.58s; +40°40’33.4’’ respectively was found at the distance of about 280 pc and 390 pc. In this present work we have calculated the dust color temperature, mass, outflow velocity, energy and size. We also studied the flux density variation and then calculated temperature and mass profile of the dust and outflow nature of AGB wind using data reduction software’s Aladin v2.5 and Aladinv8.0. Our aim was to test how outflow can be seen in this region. We have studied two cavity-like structures. The dust color temperature is found to lie in the range 21.7 K to 35.6 K for candidate I and 18.5 K to 19.3 K, with an offset of about 14 K and 0.8 K respectively. An offset of 14 K suggests that the AGB is hot in early AGB phase now in late AGB stage. We expect deviation from symmetrical outflow, i.e., AGB wind probably prefer polytropic behaviour implies bipolar type wind whereas the offset 0.8 K for candidate II suggests that the AGB is in the symmetric AGB phase, i.e., early AGB stage. The total mass of the dust in the cavity structure is found about 5.93×1025 Kg (0.00003Mʘ) for candidate I and 1.95×1027Kg (0.001 Mʘ) for candidate II. In addition we have calculated outflow energy of C-rich AGB star along ISM using outflow velocity of our candidates. It is found that the outflow velocities are 12.96 ms-1 and 10.71 ms-1 respectively. For this we have calculated the value of speed of sound (Cs) and escape velocity (uesc). In this way we have determined outflow energy, i.e., 1.173×1025J and 2.766 × 1027J respectively.The Himalayan Physics Vol. 6 & 7, April 2017 (41-47)

scholarly journals Evolved massive stars at low-metallicity

2019 ◽  
Vol 629 ◽  
pp. A91 ◽  
Author(s):  
Ming Yang ◽  
Alceste Z. Bonanos ◽  
Bi-Wei Jiang ◽  
Jian Gao ◽  
Panagiotis Gavras ◽  
...  
Keyword(s):  
Massive Star ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Initial Mass ◽  
Agb Stars ◽  
Proper Motions ◽  
Future Studies ◽  
Low Metallicity ◽  
Different Color ◽  
Yellow Supergiant

We present a clean, magnitude-limited (IRAC1 or WISE1 ≤ 15.0 mag) multiwavelength source catalog for the Small Magellanic Cloud (SMC) with 45 466 targets in total, with the purpose of building an anchor for future studies, especially for the massive star populations at low-metallicity. The catalog contains data in 50 different bands including 21 optical and 29 infrared bands, retrieved from SEIP, VMC, IRSF, AKARI, HERITAGE, Gaia, SkyMapper, NSC, Massey (2002, ApJS, 141, 81), and GALEX, ranging from the ultraviolet to the far-infrared. Additionally, radial velocities and spectral classifications were collected from the literature, and infrared and optical variability statistics were retrieved from WISE, SAGE-Var, VMC, IRSF, Gaia, NSC, and OGLE. The catalog was essentially built upon a 1″ crossmatching and a 3″ deblending between the Spitzer Enhanced Imaging Products (SEIP) source list and Gaia Data Release 2 (DR2) photometric data. Further constraints on the proper motions and parallaxes from Gaia DR2 allowed us to remove the foreground contamination. We estimate that about 99.5% of the targets in our catalog are most likely genuine members of the SMC. Using the evolutionary tracks and synthetic photometry from MESA Isochrones & Stellar Tracks and the theoretical J − KS color cuts, we identified 1405 red supergiant (RSG), 217 yellow supergiant, and 1369 blue supergiant candidates in the SMC in five different color-magnitude diagrams (CMDs), where attention should also be paid to the incompleteness of our sample. We ranked the candidates based on the intersection of different CMDs. A comparison between the models and observational data shows that the lower limit of initial mass for the RSG population may be as low as 7 or even 6 M⊙ and that the RSG is well separated from the asymptotic giant branch (AGB) population even at faint magnitude, making RSGs a unique population connecting the evolved massive and intermediate stars, since stars with initial mass around 6 to 8 M⊙ are thought to go through a second dredge-up to become AGB stars. We encourage the interested reader to further exploit the potential of our catalog.

scholarly journals Rapid grain growth in post-AGB disc systems from far-infrared and sub-millimetre photometry

2020 ◽  
Vol 494 (2) ◽  
pp. 2925-2936
Author(s):  
P Scicluna ◽  
F Kemper ◽  
A Trejo ◽  
J P Marshall ◽  
S Ertel ◽  
...  
Keyword(s):  
Grain Growth ◽  
Time Scales ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Growth Time ◽  
Agb Stars ◽  
Keplerian Orbits ◽  
Dust Evolution ◽  
Astronomical Dust ◽  
Protoplanetary Discs

ABSTRACT The time-scales on which astronomical dust grows remain poorly understood, with important consequences for our understanding of processes like circumstellar disc evolution and planet formation. A number of post-asymptotic giant branch (AGB) stars are found to host optically thick, dust- and gas-rich circumstellar discs in Keplerian orbits. These discs exhibit evidence of dust evolution, similar to protoplanetary discs; however, since post-AGB discs have substantially shorter lifetimes than protoplanetary discs, they may provide new insights on the grain-growth process. We examine a sample of post-AGB stars with discs to determine the far-infrared and sub-millimetre spectral index by homogeneously fitting a sample of data from Herschel, the Submillimeter Array (SMA), and the literature. We find that grain growth to at least hundreds of micrometres is ubiquitous in these systems, and that the distribution of spectral indices is more similar to that of protoplanetary discs than debris discs. No correlation is found with the mid-infrared colours of the discs, implying that grain growth occurs independently of the disc structure in post-AGB discs. We infer that grain growth to ∼millimetre sizes must occur on time-scales &lt;&lt;105 yr, perhaps by orders of magnitude, as the lifetimes of these discs are expected to be ≲105 yr and all objects have converged to the same state. This growth time-scale is short compared to the results of models for protoplanetary discs including fragmentation and may provide new constraints on the physics of grain growth.

scholarly journals Variation of dust properties around carbon rich AGB star- IRAS 04427+4951 using IRIS, AKARI survey

BIBECHANA ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. 154-163
Author(s):  
Devendra Raj Upadhyay ◽  
Trishna Subedi
Keyword(s):  
Physical Properties ◽  
Interstellar Dust ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Color Temperature ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Stellar Objects ◽  
Giant Branch Stars ◽  
Iris Data

Interstellar dust properties using far-infrared bands analyze nature around asymptotic giant branch stars and stellar objects. Here, we present physical properties around the cavity region across an AGB star named IRAS 04427+4951 Sky View Observatory of IRIS, AKARI map, SIMBAD, Aladin v2.5, and Gaia Archive. The average color temperature and mass are 23.48 ± 0.009 K, 3.55×1027 kg (1.79× 10-3 Mʘ ) in IRIS data and 14.89 ± 0.004 K and 5.34×1028 kg (2.69 × 10-2 Mʘ ) from AKARI data. The size of isolated cavity-like structure around the AGB stars of 45.67 pc × 17.02 pc and 42.25 pc × 17.76 pc, respectively. The visual extinction is to be in the range of 3.2×10-4 to 4.3×10-4 mag in and 4.5 × 10-3 to 7.4×10-3 mag. The inclination angle is 86.150 and 93.920. The method and results we present developed can for the study of astrochemistry of interstellar medium. BIBECHANA 18 (2) (2021) 154-163

scholarly journals Study of far infrared cavity around a post AGB star under IRAS survey at galactic latitude -3°

BIBECHANA ◽  
2018 ◽  
Vol 16 ◽  
pp. 23-30
Author(s):  
A K Gautam ◽  
B Aryal
Keyword(s):  
Local Thermodynamic Equilibrium ◽  
Far Infrared ◽  
Density Variation ◽  
Color Temperature ◽  
Galactic Latitude ◽  
Cavity Structure ◽  
Infrared Astronomical Satellite ◽  
Mass Profile ◽  
Using Data ◽  
Astronomical Satellite

A systematic search of dust structure in the far infrared (100 μm and 60 μm) under Infrared Astronomical Satellite (IRAS) survey was performed using Sky View virtual Observatory. In order to find the possible candidate of cavity structure not yet studied, we used SIMBAD database to locate discrete sources in the region. A new relatively symmetric spherical cavity like structure (size: 1.354 pc x 0.971 pc) at R.A.(J2000) =08h 03m 01.65s, Dec.(J2000) = -360 35' 47.9" was found at the distance of about 2800 pc. In this article, we have calculated  dust color temperature, dust mass  and size. We also studied the flux density variation and then calculated temperature and mass profile of the dust of p-AGB star using data reduction software Aladin2.5 and Aladin8.0. We have studied a cavity like structure centered at R.A.(J2000) = 08h 04m 07.21s, Dec.(J2000) = -370 11' 48.0". The dust color temperature is found to lie in the range 21.6 ± 0.09 K to 22.5 ± 0.05 K with an offset of 0.9 K. Such low off set suggests that the post AGB is in local thermodynamic equilibrium. The total mass of the dust in the cavity structure is found about 5.93 x 1025 Kg (0.00003M⊙)BIBECHANA 1 6 (2019) 23-30

scholarly journals A Study of a Cavity Nearby a Pulsar at -60º Latitude in the Far Infrared Map

2017 ◽  
Vol 4 (1) ◽  
pp. 33
Author(s):  
A. K. Jha ◽  
B. Aryal
Keyword(s):  
Flux Density ◽  
Region Of Interest ◽  
Far Infrared ◽  
Density Variation ◽  
Color Temperature ◽  
Dust Structure ◽  
The Past ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite ◽  
Pulsar Evolution

<p>We present physical properties of a region in the interstellar medium where the past evolutionary remnant of pulsar evolution is observed. For this, 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. Our selection criteria are as follows: (a) Cavity should be greater than 0.25 degree in diameter and (b) the cavity should have 3-fold minima in flux density. In the 100 micron infrared map, a new cavity-like isolated far infrared dust structure (size ~ 1.62 pc x 0.98 pc) is found at R.A. (J2000) 18h 33m 14.8s and Dec. (J2000) -60° 23' 24". We have studied flux density variation and temperature variation within the structure. We found that the dust color temperature varies from 22.78 K to 24.78 K, with offset of 2 K. The dust mass of each pixel of the region of interest was calculated using their dust color temperature. The excess mass in the region was found to be 1.62 x 10<sup>23</sup> Kg. The energy required to create that inhomogeneity in the structure is calculated to be 3.24 x10<sup>35</sup> J.</p><p><strong>Journal of Nepal Physical Society</strong><em><br /></em>Volume 4, Issue 1, February 2017, Page: 33-41</p>

scholarly journals Temperature and Mass Profile of Far-infrared Skeleton Nebula

2011 ◽  
Vol 1 ◽  
pp. 1-3
Author(s):  
Binil Aryal
Keyword(s):  
Star Formation ◽  
Flux Density ◽  
Far Infrared ◽  
Density Variation ◽  
Color Temperature ◽  
External Radiation ◽  
Colour Temperature ◽  
Mass Profile ◽  
Dust Grain ◽  
Map Location

Flux density variation of a newly discovered isolated far-infrared interstellar nebula (R.A. = 08h27m, Dec. = +25°54' (J2000)) is studied at 100 μm and 60 μm Infrared Astronomical Survey (IRAS) maps. The nebula contains two bright condensations ("nuclei") and several prominent filaments. The dust color temperature is estimated throughout the nebular region by dividing the 100 μm map by the 60 μm map and comparing the resulting flux I(100μm)/I(60μm) values at each map location with the values given for dust grain models by Dwek (1986). It is found that the dust colour temperature of the southern nucleus is 34±4 K and the temperature of its northern counterpart 32±4 K. The eastern filamentary structures are slightly cooler (20±2 K) than the western filamentary structures (26±3 K). Hence, the locations of the maximum emission i.e. the nuclei of the nebula are warmer than their filaments. It is interestingly noticed that there are no hints of star formation in the nebula, suggesting interaction with ambient matter or the presence of unknown external radiation. Possible explanations of the results will be explained.Key words: Nebula; Temperature; IRASThe Himalayan Physics Vol.1, No.1, May, 2010Page:1-3Uploaded Date: 28 July, 2011

scholarly journals Properties of dust in the detached shells around U Antilae, DR Serpentis, and V644 Scorpii

2018 ◽  
Vol 620 ◽  
pp. A106 ◽  
Author(s):  
M. Maercker ◽  
T. Khouri ◽  
E. De Beck ◽  
M. Brunner ◽  
M. Mecina ◽  
...  
Keyword(s):  
Mass Loss ◽  
Dust Emission ◽  
Far Infrared ◽  
Asymptotic Giant Branch ◽  
Dust Particles ◽  
Spectral Energy ◽  
Agb Stars ◽  
Dust Grains ◽  
Grain Sizes ◽  
Dust Mass

Context. Asymptotic giant branch (AGB) stars experience strong mass loss driven by dust particles formed in the upper atmospheres. The dust is released into the interstellar medium, and replenishes galaxies with synthesised material from the star. The dust grains further act as seeds for continued dust growth in the diffuse medium of galaxies. As such, understanding the properties of dust produced during the asymptotic giant branch phase of stellar evolution is important for understanding the evolution of stars and galaxies. Recent observations of the carbon AGB star R Scl have shown that observations at far-infrared and submillimetre wavelengths can effectively constrain the grain sizes in the shell, while the total mass depends on the structure of the grains (solid vs. hollow or fluffy). Aims. We aim to constrain the properties of the dust observed in the submillimetre in the detached shells around the three carbon AGB stars U Ant, DR Ser, and V644 Sco, and to investigate the constraints on the dust masses and grain sizes provided by far-infrared and submm observations. Methods. We observed the carbon AGB stars U Ant, DR Ser, and V644 Sco at 870 μm using LABOCA on APEX. Combined with observations from the optical to far-infrared, we produced dust radiative transfer models of the spectral energy distributions (SEDs) with contributions from the stars, present-day mass-loss and detached shells. We assume spherical, solid dust grains, and test the effect of different total dust masses and grain sizes on the SED, and attempted to consistently reproduce the SEDs from the optical to the submm. Results. We derive dust masses in the shells of a few 10−5 M ⊙. The best-fit grain radii are comparatively large, and indicate the presence of grains between 0.1 μm and 2 μm. The LABOCA observations suffer from contamination from 12CO (3 − 2), and hence gives fluxes that are higher than the predicted dust emission at submm wavelengths. We investigate the effect on the best-fitting models by assuming different degrees of contamination and show that far-infrared and submillimetre observations are important to constrain the dust mass and grain sizes in the shells. Conclusions. Spatially resolved observations of the detached shells in the far-infrared and submillimetre effectively constrain the temperatures in the shells, and hence the grain sizes. The dust mass is also constrained by the observations, but additional observations are needed to constrain the structure of the grains.

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