Probing the Local Bubble with Diffuse Interstellar Bands (DIBs)

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Farhang Nia, Amin | 2015

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Type of Document: Ph.D. Dissertation
Language: Farsi
Document No: 47159 (04)
University: Sharif University of Technology
Department: physics
Advisor(s): Khosroshahi, Habib; Bahmanabadi, Mahmoud
Abstract:
We present a new high signal to noise ratio spectroscopic survey of the Northern hemisphere to probe the Local Bubble and its surroundings using the 5780Å and 5797Å Diffuse Interstellar Bands (DIBs). We have observed 432 sightlines to a distance of 200 pc over a duration of 3 years. In this study, for both inside and outside the Local Bubble, we establish the 5780and 5797correlations with Na i, Ca iiand E(B-V). The correlations show that among all neutral and ionized atoms, the Na ihas more similarity with 5780and Ca iihas strong correlation with 5797, which suggest that the ionization level of 5797is more than 5780. We study the 5780correlation with 5797, which shows a tight correlation within and outside the Local Bubble (correlation coefficient: c 0.96 and c 0.94 respectively). In addition we investigate the DIB properties in UV irradiated and UV shielded regions. We find that, within and beyond the Local Bubble 5797is located in denser parts of clouds, to be protected from UV irradiation, while 5780is located in the low density parts of clouds
Keywords:
Interstellar Medium ; Bubble ; Abundance ; Local Bubble ; Diffuse Interstellar Bands (DIB)