TY - JOUR

T1 - Effects of grain growth mechanisms on the extinction curve and the metal depletion in the interstellar medium

AU - Hirashita, Hiroyuki

AU - Voshchinnikov, Nikolai V.

PY - 2014

Y1 - 2014

N2 - Dust grains grow their sizes in the interstellar clouds (especially in molecular clouds) by accretion and coagulation. Here we model and test these processes by examining the consistency with the observed variation of the extinction curves in the MilkyWay.We find that, if we simply use the parameters used in previous studies, the model fails to explain the flattening of the far-ultraviolet (far-UV) extinction curve for large RV (flatness of the optical extinction curve) and the existence of a carbon bump even in flat extinction curves. This discrepancy is resolved by adopting a ‘tuned’ model, in which coagulation of carbonaceous dust is less efficient (by a factor of 2) and that of silicate is more efficient with the coagulation threshold removed. The tuned model is also consistent with the relation between silicon depletion (indicator of accretion) and RV if the duration of accretion and coagulation is 100(nH/103 cm−3)−1 Myr, where nH is the number density of hydrogen nuclei in the cloud.We also examine the

AB - Dust grains grow their sizes in the interstellar clouds (especially in molecular clouds) by accretion and coagulation. Here we model and test these processes by examining the consistency with the observed variation of the extinction curves in the MilkyWay.We find that, if we simply use the parameters used in previous studies, the model fails to explain the flattening of the far-ultraviolet (far-UV) extinction curve for large RV (flatness of the optical extinction curve) and the existence of a carbon bump even in flat extinction curves. This discrepancy is resolved by adopting a ‘tuned’ model, in which coagulation of carbonaceous dust is less efficient (by a factor of 2) and that of silicate is more efficient with the coagulation threshold removed. The tuned model is also consistent with the relation between silicon depletion (indicator of accretion) and RV if the duration of accretion and coagulation is 100(nH/103 cm−3)−1 Myr, where nH is the number density of hydrogen nuclei in the cloud.We also examine the

KW - turbulence – ISM: clouds – dust

KW - extinction – ISM: evolution – galaxies: evolution – galaxies: ISM

U2 - 10.1093/mnras/stt1997

DO - 10.1093/mnras/stt1997

M3 - Article

VL - 437

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -