Q&A
Question

# How to calculate dust mass in ISM using AKARI and WISE survey?

There are several papers which are using following formula (as shown in the picture) to calculate the dust mass (Md) of the dusty environments such as Nebula, loops etc in the ISM. The expression for dust mass shows that it depends on grain size, grain density and grain emissivity, here, for IRAS Survey, grain size = 0.1 micron, density = 1000 kg/m3 and emissivity = 0.0010 for 100 micron, respectively, are used. Are these constants same for AKARI and WISE survey too? OR, are there any other methods for the dust mass calculation using AKARI and WISE data? I would be very much happy to get your valuable suggestions. Thank you :)

24th May, 2021
Michal Michalowski
The grain size, density and emissivity are not properties of the data/telescope (IRAS, WISE or AKARI), but of the physical objects you want to study. Hence, deciding which parameters to use is complex and must come from your knowledge of these objects. Have a look on how these parameters were derived from IRAS data - what kind of objects, assumptions, conditions? If they roughly can be applied to the objects you want to study with AKARI, then you can justify using the same parameters. If your objects are completely different then you need to somehow derive or find a different set of parameters (or at least a range of possible values).
Good luck,
Michał
24th May, 2021
University of Alabama in Huntsville
Thank you much for for your response and valuable suggestions. :)
24th May, 2021
Michal Michalowski
You are welcome!

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