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

Abstract

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.

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

“…The small variation in temperature infers that the dust cavity is evolving independently and less disturbed from the background radiation source [9]. The study of dust sub-structures around White Dwarf WD 0307+077 found that the dust temperature between 20 K to 24 K with range no more than 3 K [10]. A study of dust cavity near the Pulsar at Galactic latitude: -60 0 shows the variation of dust color temperature from 22.78 K to 24.78 K, implying that the cavity structure is less disturbed from nearby Pulsar and it's radiation [11].…”

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

“…The Infrared Astronomical Satellite (IRAS), Improved Reprocessing of IRAS Survey (IRIS) [8], AKARI infrared telescope [9], Wide Infrared Survey Explorer (WISE) [10], etc., provides the infrared map of the interstellar medium and a number of research work have been done to study the physical properties of the interstellar dust including the dust color temperature (hereafter T d ) and dust mass (hereafter M d ). The T d between 20 K to 24 K and M d is between 10 28 kg to 10 29 kg is found within the seven dust sub-structures around the WD 0307+077 using 60 m and 100 m infrared images using IRIS [11]. An infrared study of dust clouds around white dwarf PG 1225-079 shows T d 25.84 K in IRIS, 26.82 K and 27.68 K in AKARI and 291.56 K and 292.46 K in WISE data and M d is 3.44 ×10 28 kg in IRIS, 1.82 ×10 26 kg and 5.89 ×10 26 in AKARI and 1.12 ×10 26 kg and 1.14 ×10 26 kg in WISE data [12].…”

“…An IRAS study around the dust nebula located at Galactic coordinate (353.01 o , 16.98 o ) shows T d 27.92 K and M d 1.04×10 29 kg and for dust nebula located at Galactic coordinate (19.42 o , 1.98 o ) they are 31.61 K and 5.59×10 31 kg [15]. In almost all research the range of the T d is observed between the 15 K and 30 K. There is variation of M d upto 10 3 times between them because the calculated dust mass is strongly dependent on the distance of the dust cloud and there is wide variation in the value of distance used in these research work, eg., 1667.89 pc for SNRs [13], 32.73 pc for PG1225-079 [12], 399.28 pc for WD 0307+077 [11], 1219 pc for WD 0352-049 [14], 205 pc for WD 2116+675 [16], etc. The distance estimation is one of the major challenges for the dust cloud.…”

“…The background sources including the star, young stellar objects, stellar remnants and various ISM components play an important role for determining the distribution of dust color temperature within the dust cloud [13]. The range of temperature within the clouds around WD0307-377 in IRIS data [11], WD 2116+675 in IRAS data [16], dust cavities around the Pulsar in IRIS and AKARI data [18] are found less than 5 K and within the dust clouds around PG 1225-079 in IRIS, AKARI and WISE data [12], SNRs in IRIS and AKARI data [13], WD 011-394 in IRIS, AKARI and WISE data [17] are found to be greater than 5 K. The narrower dust color temperature suggests the thermal stability within the dust clouds. In this work, an infrared analysis of the dust clouds around the white dwarf LAWD-84 is performed using the data from IRIS and AKARI.…”

Comparative study of the dust color temperature and dust mass within the isolated dust in W51 giant molecular cloud in IRIS and AKARI data

“…In most of the studies T d is found between 15 K and 45 K in IRAS/IRIS data, such as; 20 K to 24 K for the dust cloud nearby WD 0307+077 [13], 22.91 K to 34.58 K for the dust nearby PG 1225-079 [14], 25.59 K to 36.82 K for the dust nearby WD 0011-399 [15], 22.67 K to 33.56 K for the dust nearby the Supernova Remnants (SNRs) in Galactic plane [16], 21.87 K to 24.09 K for the dust nearby WD 0352-049 [17], 23.77 K to 24.93 K nearby Crich AGB star 19558+3333 [18], 20.75 to 35.90 K and 22.52 to 45.63 for the dust in two different nebula [19]. In AKARI data T d is also found in the same range, such as; 17.87 K to 43.47 K nearby PG 1225-079 [14], 16.31 K to 26.37 nearby WD 0011-399 [15] and 15.78 K to 28.86 nearby SNRs in Galactic planes [16] and 16.78 K to 17.71 nearby C-rich AGB star 19558+3333 [18].…”